Taking hormone replacement therapy (HRT) could delay the onset of Alzheimer's disease for millions of women, a number of newspapers have reported today.

The reports overextrapolate the findings of a study involving 63 postmenopausal women who had been taking HRT. The research looked at the relationship between the genetic variant APOE-e4, HRT and telomere length, which is an indicator of cell ageing (see below for more information). 

The APOE-e4 gene is known to increase the risk of developing Alzheimer's disease, and previous studies have suggested a possible link between telomere length, cognitive decline and Alzheimer's disease. A possible relationship between oestrogen exposure and longer telomeres has also been found.

The researchers looked at two related questions. First, is carrying the APOE-e4 gene associated with accelerated cell ageing indicated by telomere length? Second, if so, can using HRT protect against that damage?

They found that:

• post-menopausal women who carried APOE-e4 had about six times higher odds of telomere shortening 
• women who carried APOE-e4 showed less reduction in telomere length if they stayed on HRT
• women who did not carry APOE-e4 showed less reduction in telomere length if they stopped taking HRT

It should be stressed that this was a very small study that looked at an indicator of cell ageing, not whether women developed Alzheimer's or cognitive decline.

A previous review found that HRT did not prevent cognitive decline. This current research may excite interest in whether the effect of HRT may differ in women carrying different gene variants.

The study was carried out by researchers from the University of California and other academic centres in the US. It was funded by the US National Institute on Aging and the National Institutes of Health.

It was published in the peer-reviewed open access journal, PLOS ONE.

The study's findings were over-interpreted by both The Daily Telegraph and the Daily Mail. Both newspapers reported that taking HRT may reduce the risk of developing Alzheimer's disease in women with the gene variant APOE-e4.

However, the study did not look at the potential effect of HRT on the risk of developing Alzheimer's, only at a biological sign of cell ageing. While it may be the case that this could have a knock-on health effect, this was not proven by this study.

The Independent provides the more appropriate headline, "HRT 'protects' against rapid ageing that may be linked to Alzheimer's disease, study finds."

This research was a randomised study that involved 63 post-menopausal women. It looked at whether there was an association between the genetic variant APOE-e4 that was found in some of the women, and certain biological changes linked to cell ageing. Everyone carries the gene APOE but, like other genes, it has several variants.

Cellular ageing was measured by looking at telomeres – regions of DNA at the end of chromosomes that protect the DNA as cells divide. With each division, the length of the telomeres becomes a little shorter, so telomere length is often used as a measure of biological age. Put simply, the older the cell, the shorter the telomere tends to be.

The study also looked at whether taking HRT modified any association found between APOE-e4 and changes in the length of telomeres. The researchers say there is increasing evidence that there is a link between telomere length and neurodegenerative diseases such as Alzheimer's and cognitive (mental) decline.

APOE-e4 is recognised as a genetic risk factor for Alzheimer's disease. According to the Alzheimer's Society, people with one copy of this genetic variant (estimated to be around one in four people) have a fourfold increase in risk of developing Alzheimer's disease, and people with two copies of the APOE-e4 gene variant (around 1 in 50) have a tenfold increase.

They also say there is some evidence that carriers of APOE-e4 have shorter telomeres than non-carriers, but more research is needed to establish a direct relationship.

The researchers suggest that exposure to the female sex hormone oestrogen may be associated with telomere length, but few studies have looked at the potential effect of HRT on cellular ageing.

Participants in the study were 63 healthy post-menopausal women with an average age of 57. All had been using HRT for one year or more. The women were mainly white, except for one Asian American woman. 

Genotyping (looking at people's genetic make-up) performed at the start of the study found that 24 of the women carried the APOE-e4 variant.

The women were randomly divided into two groups. One group (31 women) were taken off HRT for the two-year study period. The other 32 women remained on HRT. 

Blood samples were taken from the women at the start of the study and again after two years. Using specialist laboratory techniques, researchers measured the telomere length in their white blood cells both at the start of the study and again after two years.

The researchers found that, overall, women who carried the APOE-e4 variant had six times greater odds of telomere shortening over the two years than non-carriers (odds ratio 6.26, 95% confidence interval 1.02 to 38.49).

The analysis took into account factors (confounders) that could affect results, such as the women's age, education, their use of HRT and how long their telomeres were at the start of the study. Overall, if APOE-e4 was taken into account, HRT use did not affect odds of telomere shortening.

The researchers then looked within the individual treatment groups for differences between APOE-e4 carriers and non-carriers. Among the group who remained on HRT, there was no significant difference in telomere length between carriers of the APOE-e4 gene and non-carriers. But in the group who stopped HRT, carriers of APOE-e4 had more telomere shortening than non-carriers, who actually showed an increase in telomere length.

The researchers say the study demonstrates an association between APOE-e4 and telomere length, with carriers of APOE-e4 having "marked telomere attrition" during the two years of the study.

They calculate that in two years, the telomeres of these carriers shortened by an amount equivalent to what might be expected to take a decade in non-carriers.

In addition, they suggest that HRT may "buffer" against accelerated cell ageing in post-menopausal women at risk of dementia. 

They point out that, importantly for women who do not carry the APOE-e4 gene, there was no evidence that HRT had a "protective effect" on telomeres.

They also suggest that HRT may have different effects on cell ageing across different genetic subgroups, as stopping HRT had "beneficial effects" on telomere length for non-carriers of the gene variant.

This small study appears to have found an association between the gene variant APOE-e4 and the rate at which telomeres become shorter, which is usually regarded as a biological sign of cell ageing.

It does not show that HRT can help prevent Alzheimer's in women who carry the APOE-e4 gene variant. This analysis is an exaggeration of the researchers' findings by the press.

A systematic review from the Cochrane Collaboration in 2008 suggested that, at the time, there was good evidence that HRT did not prevent cognitive decline in older postmenopausal women when given in the short or longer term (up to five years). However, the Cochrane review did not look at whether the effect differed in women with different genotypes.

It is possible that, with only 24 carriers of the gene included, the findings are not representative of what would be seen in a larger group of women. A far larger trial that follows women for several years and looks at clinical outcomes is required in order to find out what the effects of HRT are on this group.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

HRT 'protects' against rapid ageing that may be linked to Alzheimer's disease, study finds. The Independent, February 14 2013

HRT could help delay onset of dementia. The Daily Telegraph, February 14 2013

HRT cuts Alzheimer risk. Daily Express, February 14 2013

Links To Science

Jacobs EG, Kroenke C, Lin J, et al. Accelerated Cell Aging in Female APOE-ε4 Carriers: Implications for Hormone Therapy Use. PLOS ONE. Published online February 13 2013

Could how high people live affect their weight? Do slimmers need to head for the hills? Reuters has reported on a new study that suggests that people who dwell at high altitude are less likely to be obese.

The research found that people who lived at less than 500m above sea level (such as New Yorkers) were much more likely to be obese than people who lived 3,000m or more above sea level (such as people who lived in Denver, Colorado).

Even after taking into account factors that may be associated with life at higher altitudes, such as increased physical activity (possibly due to more climbing) and colder temperatures, there was still a significant link between higher altitudes and obesity rates.

Researchers found that men living at altitudes below 500m were 5.1 times more likely to be obese compared with their counterparts living above 3,000m. Meanwhile, women living at these low levels were 3.9 times more likely to be obese.

While the researchers can’t pin down the exact cause of this relationship, they speculate that low oxygen levels at high altitude, which increase energy demands and potentially influence foetal and child development, may be responsible. However, it is likely that the connection between altitude and obesity is part of a complex relationship between biology, demographics, environment and lifestyle factors.

The study was carried out by researchers from the University of the Health Sciences, Bethesda, and Virginia Commonwealth University and Obetech Obesity Research Center, Richmond, USA. No sources of financial support are reported.

The study was published in the peer-reviewed medical journal International Journal of Obesity.

The researchers highlight the observed trend that, in the US, obesity seems to be most prevalent in the southeastern states and Midwest, and less so in the ‘mountain west’ states. They say that differences in elevation provide a biologically plausible explanation, with suggested theories including increased metabolic demand and reduced childhood growth in response to altitude.

However, other observational studies of different populations worldwide have given varied results. For example, people in Peru have higher than average rates of obesity-related diseases despite living at a higher altitude.

This cross-sectional study aimed to look at the geographic distribution of obesity across the US and see how it related to elevation level, temperature and urbanisation, while also adjusting for other behavioural and demographic factors.

Such a study can demonstrate an association between obesity levels and altitude. But it cannot prove that altitude has a direct effect on BMI or say what biological process causes this.

This research used 2011 data gathered from the Behavioral Risk Factor Surveillance System (BRFSS), which is said to be a nationwide telephone health survey representative of the US population.

The collected data included information on diet and physical activity and demographic details (age, sex, race or ethnicity, education and income). Obesity was defined as body mass index (BMI) of 30 kg/m2 or greater – which is an internationally agreed definition.

Elevation above sea level, average annual temperature and urbanisation for participants was based on their county of residence reported in the 2011 survey. They had these data for 3,134 administrative areas (counties) within the US.

The researchers used statistical methods to look at the association between obesity and elevation above sea level, average annual temperature and urbanisation, taking into account the demographic and lifestyle factors data they had.

The researchers had full data available for 422,603 US citizens. The researchers found that, compared with the 322,681 people at the lowest level of elevation (less than 500m above sea level) those 236 people at the highest level of elevation (3,000m or more above sea level) were less likely to smoke and were more likely to comply with physical activity and diet recommendations.

After taking into account temperature, urbanisation, demographic factors and lifestyle factors (such as physical activity and diet), men living at less than 500m above sea level had 5.1 times the odds (95% confidence interval [CI] 2.7 to 9.5) of being obese compared with those living at 3,000m. Women had 3.9 times the odds (95% CI 1.6 to 9.3) of being obese. Those living at more than 3,000m had an average BMI 2.4 units lower than those living at less than 500m. They found a tendency for obesity prevalence to decrease with each 200m increase in elevation, although this was not a straight line relationship.

When looking separately at the relationship between obesity and temperature, the researchers found that people tended to have lower BMI at the extremes of temperature (lower annual averages or higher annual averages), while the highest BMIs tended to be observed among those with average annual temperature around 18°C.

When looking separately at the effect of urbanisation they found that the prevalence of obesity tended to decrease with increasing urbanisation.

The researchers conclude that obesity prevalence in the United States is inversely associated with elevation, after adjusting for urbanisation, temperature, diet, physical activity, smoking and demographic factors. Obesity prevalence is also inversely associated with urbanisation, after adjusting for these other factors – bigger cities have lower average obesity rates.

So would moving to a high altitude really help you lose weight? Potentially, but you’d have to leave Britain. The 3,000m height that researchers looked at is more than twice as high as Ben Nevis, Britain’s tallest mountain.

This was a large study that included a nationally representative sample of US citizens and used reliable geographic data on elevation, temperature and urbanisation. As such it was a strong study and the results can be believed.

The researchers suggest that the observed link between elevation and obesity is unknown but could be due to mechanisms such as the lower oxygen levels at high altitude, which are known to increase metabolic demands and influence hormones involved in metabolism. It could also possibly influence foetal and child growth, which could have a corresponding effect on a child’s future weight. However, the evidence of obesity levels from other mountainous countries suggests it may not be as simple as that. The relationship recorded by this research may be unique to the US.

Despite the reliable measures used in this study it does have limitations. Its cross-sectional design means that it is very difficult to conclude that altitude has a direct effect on BMI. Nor does it allow us to determine what biological process underlies the link.

Although the researchers have found that the relationship was independent of temperature, urbanisation, physical activity, diet and other lifestyle factors, as well as demographic factors (such as education and income), it is possible that the influence of all of these factors has not been completely removed or that not all factors have been considered.

It is likely that the connection between altitude and obesity is part of a complex relationship between biology, demographics, environment, lifestyle and historical factors. Due to the fast-changing demographics of the United States, the ethnic and genetic make-up of a region such as New York State (known for its large immigrant population) may be significantly different to a state such as Colorado.

One final point raised by the researchers is that, if it were proved that environmental factors associated with high altitude were responsible for weight loss then oxygen tanks could be used to replicate these conditions to aid weight loss. However, this does seem rather extreme, as would moving to a higher altitude, such as Colorado.

Despite the media headlines, the study has not examined whether, if you are overweight or obese, moving to a higher altitude country will help you to lose weight. The best advice for those wanting to shed a few pounds remains that you need to combine a healthy, balanced diet with around 150 minutes of exercise each week.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Home altitude tied to obesity risk. Reuters Health, February 12 2013

Links To Science

Voss JD, Masuoka P, Webber BJ, et al. Association of elevation, urbanization and ambient temperature with obesity prevalence in the United States. International Journal of Obesity. Published online January 29 2013

The news that lung cancer is now the leading cause of cancer-related deaths in British women is being widely reported by the media. The stories are based on well conducted research that predicts cancer deaths in 2013.

The study estimated how many deaths there will be from all forms of cancer across the European Union. As per the headlines, it found that lung cancer now outstrips breast cancer as the main cause of cancer deaths among women in the UK.

The rise in lung cancer deaths may be caused by:

• the long-term effect of the greater number of women smokers during the 1960s and 70s
• the fact that lung cancer remains challenging to treat, as it is often not diagnosed until it is at an advanced stage 

The study also had some good news: it found that between 2009 and 2013, overall death rates for most cancers look likely to decline in Europe, although this decline is only 1% for the UK.

This research reinforces the fact that the dangers associated with smoking often do not develop for many decades. But if women quit before they are 40, they can significantly reduce their risk of dying from causes related to smoking. Regardless of gender, quitting at any age will bring benefits.

Where did the story come from?

The study was carried out by researchers from a number of European centres in Italy and Switzerland, and was funded by the Swiss Cancer League and the Italian Association for Cancer Research.

It was published in the peer-reviewed journal, Annals of Oncology.

Understandably, the UK media mainly concentrated on the cancer figures for the UK, especially the lung and breast cancer death rates in women. While the reporting was generally accurate, other worrying trends predicted in the study – such as deaths from pancreatic cancer showing no signs of falling – were mostly unreported.

This research was an estimate of predicted death rates from different cancers and cancer overall in the 27 EU countries for 2013. The study follows similar estimates for 2011 and 2012.

Researchers modelled their predictions on previous cancer mortality rates using data from the World Health Organization (WHO). In particular, the researchers carried out detailed analysis of gastrointestinal cancers.

The researchers obtained official data on deaths from cancer from the WHO mortality and population database. Using complex statistical methods, the researchers used this data to model predictions for cancer death rates across Europe in 2013.

They computed age-specific rates for each five-year age group (from 0-4 to 80 years plus) to compute age-standardised death rates across Europe. The figures for the EU were taken from the period 1970 to 2009.

The cancers they looked at were:

• intestinal (colon and rectum) 
• pancreas
• lung
• breast
• uterus (cervix and womb) 
• prostate
• leukaemias
• total cancer mortality overall

The researchers also looked at cancer rates in six individual countries, using the most recent data available to build their predictions. The countries included were France (2010), Germany (2010), Italy (2009), Poland (2010), Spain (2010) and the UK (2010).

Types of cancer were coded according to an international classification of disease. Estimates of each country's population size and age structure were obtained from the same WHO database or, in the case of the France and the UK, from a European database.

The study predicts that there will be 1,314,296 deaths from cancer in the EU in 2013 (737,747 men and 576,489 women). This is a slightly higher figure than that for 2009 as the population as a whole has grown slightly older.

However, the researchers found the actual rate of people who die from the disease continues to decline. Between 2009 and 2013, adjusted death rates from cancer are predicted to fall by 6% (to 140.1 per 100,000) in men, and by 4% (to 85.3 per 100,000) in women.

By 2013 the average EU adjusted death rates (per 100,000) from specific cancers are predicted to be:

• 6.6 in men and 2.9 in women for stomach cancer
• 16.7 in men and 9.5 in women for cancer of the intestines
• 8.0 in men and 5.5 in women for pancreatic cancer
• 37.1 in men and 13.9 in women for lung cancer
• 10.5 in men for prostate cancer
• 14.6 in women for breast cancer
• 4.7 in women for uterine cancer
• 4.2 in men and 2.6 in women for leukaemia

Across Europe, these figures represent a fall in death rates from all cancers, apart from lung cancer in women and pancreatic cancer.

Female cancers

In 2010, there were 19,447 deaths among UK women from lung cancer and 11,575 deaths from breast cancer. The prediction for 2013 is 19,535 deaths from lung cancer and 10,983 deaths from breast cancer. Among the six major countries for which the predictions are available, the UK is predicted to have the lowest overall cancer death rate for 2013, 10% lower than the average EU rate.

Pancreatic cancer

Across Europe, pancreatic cancer is the only cancer for which death rates are not predicted to decline in both sexes. For 2013 the death rate is predicted to be 8 per 100,000 in men and 5.5 per 100,000 in women, compared with 7.9 and 5.4 in 2009. At 6.6 per 100,000 among men, the UK has lower rates than the European average.

Lung cancer

Despite the overall decline in cancer deaths, lung cancer rates continue to rise among women across Europe – by 7% since 2009 – while breast cancer rates fall. In 2013 there will be an estimated 88,886 deaths among women from breast cancer (a rate of 14.6 per 100,000) and 82,640 (14 per 100,000) from lung cancer.

The researchers point out that although overall cancer death rates are predicted to decline, within the EU there are wide disparities in cancer mortality, showing there is still "large room for improvement".

On the positive side, a steady decline in mortality is predicted for all cancers, apart from pancreatic cancer and lung cancer in women. They say that the decline in cancer mortality is likely to be due to early diagnosis and screening as well as better treatment.

The researchers say that the steady increase across Europe in lung cancer mortality among women is expected to continue, and by 2015 it may become the leading cause of cancer deaths among women.

This is already the case in the UK and Poland, the countries with the two highest rates of lung cancer among women. They say that it is possible the recent increase in deaths from lung cancer among UK women may be transient, due to the rise in smoking among young women in the 1970s. 

Death rates from this disease could level off and should decrease in future years as fewer people are now smoking, so future smoking-related deaths should eventually fall.

Although the figures given for 2013 in this study are estimates, they are likely to be close to the mark, reflecting the trends in cancer death rates seen since 2009.

In both Europe and the UK, the news that death rates from cancer are falling – and are predicted to continue to do so – is encouraging and reflects improved treatment, screening and earlier diagnosis for this disease.

Clearly, the increasing number of deaths from lung cancer among women is disturbing, as is the lack of improvement in mortality from pancreatic cancer.

Encouraging people to stop smoking and avoid being overweight, coupled with improved treatments, may help reduce the number of people who develop these diseases and improve death rates.

For advice on giving up smoking, visit smokefree.nhs.uk.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Lung cancer 'overtaking breast cancer in European women'. BBC News, February 13 2013

Lung cancer overtakes breast cancer as most deadly form of disease among UK women. The Daily Telegraph, February 13 2013

Lung cancer has become the most lethal form of the disease for women. The Guardian, February 13 2013

Growing toll of smoking on UK women as it's revealed more die from lung than from breast cancer. Daily Mail, February 13 2013

Links To Science

Malvezzi M, Bertuccio P, Levi F, et al. European cancer mortality predictions for the year 2013. Annals of Oncology. Published online February 12 2013

‘Children from middle-class families are generally fatter than their poorer counterparts’, The Independent reports.

The news, covered by much of the media, is based on research reconfirming the fact that obesity is highly prevalent among children across all backgrounds. However, this large and well- designed study produced results that seem to contradict most previous evidence, by finding that childhood obesity was not most prevalent among more ‘deprived’ children.

The three-year study, based in Leeds, found that children aged 11-12 years were more likely to be obese if they came from small areas classed as being around the average on a deprivation rating. Levels of obesity were high in all groups, but the children from the most income deprived and least income deprived areas were less likely to be obese than those in the middle.

On its own, this research is not strong enough to prove that the current way of thinking about the link between deprivation and obesity is wrong. However, it does give pause for thought, and highlights the need for further, more focussed research.

The study was carried out by researchers from Leeds Metropolitan University in the UK. No explicit funding source was described, but the authors declared no conflicts of interest.

The study was published in the peer-reviewed International Journal of Obesity.

The media generally reported the research accurately, with most highlighting that the results challenge the currently held view (based on previous evidence) that obesity levels rise in line with higher levels of deprivation in a relatively linear fashion.

This was a cross-sectional study aiming to investigate associations between a measure of area-level deprivation and three measures of fatness in children:

• body mass index (BMI)
• waist circumference
• waist-to-height ratio

The researchers acknowledge that past findings indicate the prevalence of obesity is highest in more deprived groups. However, they point out a limitation in this evidence base, as it relies on individual levels of deprivation (such as household income), rather than area-level deprivation (the proportion of households in a local area or community that are above or below a threshold for household income).

Researchers wanted to know if the way deprivation was measured influenced the true link between childhood obesity and deprivation. Furthermore, they indicated most previous research has used BMI to measure fatness in children. Other measures of ‘fatness’, such as waist circumference or waist-to-height ratio, may provide a better understanding of the relationship between deprivation and obesity.

A cross-sectional study is a good way of establishing obesity levels at a particular point in time. However, as information is collected at just one point in time, it cannot categorically prove that deprivation causes obesity, only that the two are linked in some way.

Understanding the link between childhood obesity and deprivation is important from a public health perspective. For example, if obesity is found to be linked to different levels of deprivation, local health promotion resources can be targeted proportionately at the groups most in need.

Data for this study was obtained from the Rugby League and Athletics Development Scheme (RADS) over a three-year period from 2005 to 2007.

RADS was described by the researchers as a collaboration between Leeds City Council, Leeds Metropolitan University and the Education Authority (Education Leeds), and was set up to identify talented children who were then offered a place on a talent development programme. It was also set up to monitor obesity levels in the city.

The programme involved a series of basic fitness assessments and physical measurements of all year-seven (age 11 years) children from 37 secondary schools in Leeds who agreed to participate. Response rates for the programme were consistently above 80% of pupils. Researchers also measured children’s height, weight and waist circumference while they were at school.

The researchers converted the children’s weight and height measurements to BMI scores. Using standardised reference charts, children were classified as obese if their BMI fell outside the normal range, that is, outside the range you would expect 95 out of 100 children to be in if they had a normal BMI. A waist-to-height ratio of 0.5 was used to “define increased concern”.

Childhood deprivation for each area was estimated by assigning a standard childhood measure of deprivation (the Income Deprivation Affecting Children Index or IDACI) to the geographical areas where the child lived. The geographical areas used are called lower super output areas (LSOAs). These are areas generated to establish similar sized groups (around 1,000 to 1,500 people in each) that share similar house types and tenures (for example, whether the properties are rented, owned, or are occupied by council tenants).

The IDACI score is the proportion of children (aged 0–16 years) in each LSOA who live in income deprived households. ‘Income deprived’ was defined as a household receiving at least one of the following benefits:

• Income Support
• Jobseekers Allowance
• Working Families Tax Credit
• Disabled Persons Tax Credit

The statistical analysis used by the researchers was appropriate and compared whether children were obese or not to levels of deprivation in their area.

Over the three years, 15,841 children took part in the study programme. Researchers excluded from their analysis information on any children they did not have complete data for. The final analysis used data from 13,333 children with measures of BMI, and 13,133 children with measures of waist circumference or waist-to-height ratio from 37 schools in 542 LSOAs. The researchers found that:

• There were considerable differences in the prevalence of obesity estimated in the same children using the three different measures of fatness. Combining the three years of data, the obesity levels were 18.6% (using BMI), 26.8% (using waist circumference) and 18.5% (using waist-to-height ratio).
• No statistically significant linear relationship (a straight line on a graph) between area-level deprivation and obesity was found. That is, no direct link was found between higher deprivation levels and higher obesity levels. Even so, a small (non-significant) linear pattern was observed and appeared stronger in girls than boys.
• There was a non-linear pattern (that is, not a straight line but more of a curve on a graph) between area-level deprivation and obesity across all three measures of fatness.
• For all measures of obesity, the highest probability of being obese was around the middle of the income deprivation range (termed ‘middle class’ in the papers). Those in the highest and lowest areas of deprivation were less likely to be obese. The obesity-deprivation relationship varied significantly between boys and girls. The risk of being obese for boys did not peak in the middle deprivation range as much as it did in girls.
• ‘Non-white’ children were more likely to be obese than ‘White-British’ children.

The researchers concluded there “are inconsistencies between the different measures of obesity” and that “the relationship between obesity and deprivation does not seem to be linear”.

This research describes a non-linear relationship between area-level deprivation (at a local level) and childhood obesity. It suggested those in the middle range of deprivation were the most likely to be obese, more so than children living in the most deprived or least deprived areas.

As the news headlines suggest, this appears to go against other evidence and the commonly held assumption that childhood obesity increases as deprivation increases in a relatively linear (one-to-one) fashion.

The study has important strengths, including its large sample size and use of multiple measures of childhood fatness to estimate obesity, but there are also limitations to consider.

Using lower super output areas

LSOAs are artificial catchment areas and may not always reflect areas important to the individuals living within them. For example, they might divide a housing estate or other significant community boundary that influences deprivation. So using different geographical areas to define deprivation may influence the results.

Measure of deprivation used

The measure of deprivation (IDACI) is based on a number of things, including income of the households where the child lives. It is possible different results would be found using different measures of deprivation. Ideally, multiple measures of deprivation would be used to assess the influence. The researchers used different measures of fatness and noted how this influenced the estimates of obesity massively. Similar differences may be observed using different measures of deprivation. This could influence the results.

Recruitment to the study

Data for this study came from the Rugby League and Athletics Development Scheme that invovled a series of basic fitness assessments and physical measurements of all year-seven (age 11 years) children from 37 secondary schools in Leeds who agreed to participate. It is possible there was selection bias using data obtained through this scheme. That is, the children in the 37 schools that agreed to participate may be systematically different from the schools that chose not to take part in the study. For instance, the schools electing not to take part may have been in more deprived areas with less facilities or interest in sporting activities, or other class related differences affecting the schools' appetite for signing their pupils up for a rugby league development scheme. A different relationship may have been found if all schools in Leeds participated.

Applicability to rest of UK

The study sample was restricted to children aged 11-12 years living in Leeds. This limits how applicable it is to children of other ages living in other areas of the UK. If the research had recruited children from more age groups, a larger geographical area, or from more ethnically diverse groups, the results may have been different.

Furthermore, if other parts of the country were included, it would have been possible to assess the link across a broader range of income deprivation levels. For instance, the middle income deprivation level (or middle class children as the papers put it) in Leeds might not be the same as in other cities like Oxford or Cambridge and this might influence the link between deprivation and childhood obesity levels found in these places, or across the UK as a whole.

Further research along these lines is needed to confirm whether the relationship observed in this group is also true for the rest of the children in the UK. At present this is unclear.

This research is not strong enough on its own to say that the current way of thinking is wrong, but it does given reason for a pause for thought. As with all good science, evidence challenging established ways of thinking is considered on merit and discussed by experts in the field. More research is needed to confirm or refute this current piece of research before any practical changes can be hinged on its unique findings.

This research questions the orthodoxy that childhood obesity increases in line with increasing deprivation. However, it stops short of proving that this is not the case.

At the same time, it serves to reinforce the fact that obesity is highly prevalent among the population: for rich and poor alike.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Minister was wrong to say obese children come from poorer homes. The Independent, February 12 2013

The waddle classes: Most obese kids 'from middle class not poor families'. Daily Mirror, February 12 2013

Middle-class children 'fatter' claims study. The Daily Telegraph, February 12 2013

Middle-class children are more likely to be obese than those from poorer backgrounds. Daily Mail, February 12 2013

Youngsters ‘more likely to be fat if middle class’. Metro, February 12 2013

Obesity ‘is worst in Middle Britain’. Daily Express, February 12 2013

Links To Science

Griffiths C, Gately P, Marchant PR, et al. Area-level deprivation and adiposity in children: is the relationship linear? International Journal of Obesity. Published online February 12 2013

‘Babies delivered by caesarean section at higher risk of asthma and allergies’, the Mail Online reports. This rather bold claim is based on a tiny, genetic study. A link between caesareans and asthma or allergy cannot be proven from the research this story appears to be based on.

In the study, researchers looked at bacteria in the gut of 24 babies to see if there were differences between babies who had been delivered naturally (vaginally) and those delivered by caesarean section. They also looked at whether they were breastfed during their first three to four months of life.

Researchers wanted to test the theory that natural delivery and breastfeeding helps stimulate the production of healthy bacteria in the gut.

They confirmed that, in their small sample, the caesarean-born babies had lower ‘richness’ and diversity of bacteria species compared to naturally born babies. A similar pattern was not found when breastfed and formula-fed babies were compared – formula-fed babies actually had higher ‘bacterial richness’, which the researchers say is consistent with previous studies.

This is of potential interest as there is a general consensus that gut bacteria has been linked to an increasing number of diseases, including type 1 diabetes, obesity, cancer, allergies, and asthma.

However, this was such a small study, involving single measurements taken at only one point in time, that it cannot prove any link between caesarean sections, breastfeeding, gut bacteria and the likelihood of developing a long-term disease.

The researchers note these findings are part of ongoing research and that future reporting will provide more information.

The study was carried out by researchers from the Universities of Alberta and Toronto, Canada, among other institutions. It was funded by the Canadian Institutes of Health Research and supported by AllerGen NCE, the Killam Trusts and Alberta Innovates – Health Solutions. The study was published in the peer-reviewed Canadian Medical Association Journal.

The results of the study were exaggerated in the Mail Online’s headline. The researchers have just taken a first step in attempting to establish a link between caesarean section and disease, but the headline implies they are already at the finish line.

Reassuringly, once you get past the headline, the study was covered appropriately. The print edition of the Daily Mail carries the possibly better headline 'Caesarean babies "lack protection of vital bugs"'.

This was a cross-sectional study looking at the gut bacteria of babies, and how this differed depending on whether they were delivered naturally or by caesarean section, and whether they were breastfed or fed formula during their first three to four months of life.

The researchers say that the development of bacteria in the gut in the early part of a person’s life is poorly understood. However, the design of this study means that it arguably adds little to that understanding. It only examined the gut bacteria of an extremely small sample of babies at one point in their life and can tell us little else about the causes of these bacterial levels, or how they related to longer-term health outcomes.

It could be the case that this was a ‘proof of concept’ piece of research – to see if the genetic sequencing techniques used in the study could provide useful results.

Researchers included 24 healthy babies from the wider national Canadian Health Infant Longitudinal Development (CHILD) study, which is reported as being representative of the infant population in Canada.

The researchers obtained information on the type of delivery (natural or caesarean) from medical records as well as use of antibiotics, group B streptococcus infection (a bacteria that can cause severe infection in newborns), and whether there was early (premature) rupture of the amniotic membrane surrounding the baby (which can increase the risk of infection). The mothers of the babies were asked to report on their baby’s diet during the first months of life, and whether this was categorised as exclusively breastfed, partially breastfed or not breastfed. They were also asked about any medication use by the mother or baby.

Samples of the baby’s faeces were then collected when the infant was three to four months old and researchers examined the gut bacteria from these samples using specialist DNA sequencing techniques.

Of the 24 babies included in the researchers’ analysis, 25% were delivered by caesarean section (six babies) and 75% were delivered naturally (18 babies). By the time the babies were three to four months old:

• 42% were exclusively breastfed (10 babies)
• 21% were partially breastfed (five babies) – supplemented with formula
• 38% were not breastfed (nine babies)

Exclusive breastfeeding was more common among infants born naturally (44%) compared to caesarean delivery (33%).

The main findings of the study were:

• Compared to babies who were delivered naturally, caesarean delivered babies had significantly lower amounts of a type of ‘good’ bacteria. 
• Compared with babies who were breastfed, those who were not breastfed had significantly higher amounts of ‘bad’ gut bacteria.
• The amount of a particular ‘bad’ bacteria called Clostridium difficile was significantly lower among exclusively breastfed babies than among babies who received formula. This finding was not affected by the type of delivery.
• Formula-fed infants had increased ‘richness’ and diversity of bacteria species compared to breastfed babies.
• Meanwhile, caesarean delivered babies had the lowest ‘richness’ and diversity of bacteria species compared to naturally born babies.

The researchers conclude that bacteria in the gut can be influenced by parent and physician decisions regarding the type of delivery and infant diet. They say that further research is needed into the determinant of the gut bacteria and any associated health outcomes.

In discussing the research findings, co-author Dr Anita Kozyrskyj, of the University of Alberta, is reported as saying, ‘Our findings are particularly timely given the recent affirmation of the gut microbiota as a “super organ” with diverse roles in health and disease, and the increasing concern over rising caesarean delivery and insufficient exclusive breastfeeding.’

Overall, this research provides some information on the amount of particular bacteria species present in the gut in the first few months of life of an extremely small number of babies. The study does not provide any evidence that the mode of delivery or feeding pattern was the cause of the bacterial levels measured. Neither does the study provide any evidence that being born by caesarean delivery leads to developing asthma later on in life, as the headline in the Mail Online suggests.

The researchers note that these findings are part of an ongoing study and future reporting will provide more information. There are some limitations to this study some of which are noted by the authors, including:

Researchers based their analysis on one measurement taken at one point in time (when the baby was three to four months old). The researchers note that previous studies suggest gut profiles vary widely in the first year of life. A more comprehensive study would have taken measurements at a number of time points of the child’s life, to determine if any changes in gut bacteria occurred. However, even then it would be difficult to pin an exact cause on the levels seen which are likely to be influenced by multiple factors.

Only 24 babies were included in the study. A study of this size is too small to reliably detect any differences between natural and caesarean deliveries, and formula and breastfed babies, and even less so to detect any differences according to type of caesarean delivery (emergency vs. elective) or brand of infant formula, for example.

Overall, no conclusions can be drawn from this small study of 24 babies.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links To The Headlines

Babies delivered by Caesarean section at higher risk of asthma and allergies. Mail Online, February 11 2013

Caesarean deliveries and formula feeding linked to lifelong diseases: research. The Daily Telegraph, February 12 2013

Links To Science

Azad MB, Konya T, Maughan H, et al. Gut microbiota of healthy Canadian infants: profiles by mode of delivery and infant diet at 4 months. Canadian Medical Association Journal. Published online February 11 2013

'Eye gene discovery may end the need for glasses,' is the somewhat optimistic headline in the Daily Express. The story looks at a wide-ranging and well conducted study that has also been reported on by the Daily Mail and The Independent. 

The study investigated whether certain genes increase the risk of developing refractive errors, which are errors in the way the eye focuses light. Researchers were especially interested in genes that increase the risk of short-sightedness (myopia).

The researchers looked for genetic variants associated with refractive errors among more than 45,000 people. They found 26 genetic variants, two of which had previously been linked to refractive errors, plus 24 new variants. They then calculated that people carrying all the genetic variants were 10 times more likely to become short-sighted.

Sadly, learning more about the genetics of short-sightedness doesn't automatically lead to new treatments – at least not in the short-term. As the Mail rightly pointed out, "any drug to prevent [the] condition is at least 15 years away."

Where did the story come from?

The study was carried out by an international team of researchers called the Consortium for Refractive Error and Myopia (CREAM). This study included data from several other studies, which were mainly funded by governments.

It was published in the peer-reviewed journal Nature Genetics.

The discovery of genetic variants can feed into research into how errors develop in the way eyes focus light. It is hoped that treatments can be developed once this is better understood, but the timescale for any developments is unknown.

The Express' slightly overblown headline was followed by a brief – but accurate – report. While the Mail's headline, 'Found, genes that could save millions from short-sight and lead to a drug to combat condition,' was also a bit too hopeful, its story did cover the results of the study accurately and struck an appropriate tone of cautious optimism.

The Independent's story was also largely good. However, its online and print versions differed, with the internet version being sensible and accurate, using the headline 'Scientific breakthrough in study of the genetics of myopia.' However, The Independent's newspaper headline, 'Outdoor play "can prevent childhood short-sightedness",' appears to be based on an aside made by one of the researchers and is not founded on any of the evidence presented in the published study.

This was a meta-analysis combining the results of 32 studies from Europe, the United States, Australia and Asia. Twenty-seven of the studies included people of European ancestry and five studies included people of Asian ancestry.

The researchers performed a genome-wide association study to see if they could identify genetic variants that were associated with refractive errors (errors in focusing light that often result in reduced vision). 

Genome-wide association studies are an excellent method of identifying genetic variants that may be associated with diseases. They involve taking a sample of DNA and then studying the millions of different genetic variations in the human genome contained in the sample.

However, it still remains to be determined how the genetic variants found affect the eye. The development of treatments that could prevent or correct eye defects is a long way off, despite headlines in the papers that suggest that the results of this study could end the need for glasses.

The researchers initially performed a genome-wide association study to look for genetic variants that were associated with worse "spherical equivalent". Spherical equivalent is a measure of the eye's focusing power and corresponds to the strength of lens needed to correct a deficiency in focusing (the worse a person's vision, the stronger the lens needed to correct it).

The researchers first used data from 37,382 individuals from the 27 studies of people of European ancestry. They then looked at whether the genetic variants identified in the European cohorts were linked to refractive error in 8,376 individuals from five studies of people of Asian ancestry.

A genome-wide meta-analysis was performed using data from all the individuals (45,758 people in total). The influence of the genetic variants on the risk of developing myopia (short-sightedness) was then calculated.

Finally, the researchers speculated on how the genetic variants could influence the development of refractive error and myopia.

The researchers identified 309 single nucleotide polymorphisms (SNPs, which are variations in a single DNA base) that were associated with refractive error. These SNPs were located in 18 different regions of the genome.

They took the 18 SNPs with the strongest association with refractive error and tested whether they were associated with refractive error in people of Asian ancestry. Ten of the SNPs were found to be statistically associated with refractive error in this population.

The researchers also found eight further SNPs that were significantly associated with refractive error when they combined the data for all 45,758 individuals.

In total they identified 26 SNPs associated with refractive error. Two of the SNPs had already been described, while the other 24 SNPs were new.

The researchers then looked at how having these SNPs corresponded with the risk of developing refractive errors using data from studies performed in Rotterdam.

People identified as being at high genetic risk (who had the identified SNPs) were found to have a tenfold increased odds of becoming myopic (odds ratio of 10.97, 95% confidence interval (CI) 3.37 to 31.25).

The researchers found that many of the SNPs identified were located in or near genes that code for proteins produced in the retina of the eye. They state that many of the genes identified could play a role in the development of refractive problems.

The researchers conclude that they have identified 24 new genetic positions associated with errors in the way the eye focuses light, resulting in impaired vision. People carrying the highest number of genetic risk factors have a tenfold increased risk of myopia.

The researchers go on to say that further research into how these genetic variants affect eye growth could lead to improved vision for people with myopia.

This study has identified 26 genetic variants found to be associated with problems in the way the eye focuses light (refractive errors). Two of the variants were linked to refractive errors previously, and 24 of the variants were new.

Using data from people enrolled in a cohort study in Rotterdam, the researchers calculated that people with the most adverse genetic variants (those with the highest risk score) had a tenfold increase in the odds of becoming short-sighted. The highest risk score occurred in less than 5% of subjects.

Although this is exciting research, contrary to some of the headlines, treatments or prevention strategies are likely to be a long way off. The discovery of genetic variants can feed into research into how errors in focusing light develop. Once this is better understood, it is hoped that treatments can then be developed, but this is far from guaranteed and the timescale for any developments is unknown.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Found, genes that could save millions from short-sight and lead to a drug to combat condition. Daily Mail, February 10 2013

Scientific breakthrough in study of the genetics of myopia. The Independent, February 10 2013

Eye gene discovery may end the need for glasses. Daily Express, February 11 2013

Links To Science

Verhoeven VJM, Hysi PG, Wojciechowski R, et al. Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia. Nature Genetics. Published online February 10 2013

Most of the UK media is covering the announcement made in Parliament by Jeremy Hunt, Secretary State for Health, about proposed changes to social care.

The two confirmed points to have garnered the most media attention in the run-up to the announcement are:

• a ‘cost cap’ of £75,000 worth of care costs – after this point the state would step in to meet these care costs
• raising the current means-testing threshold for people to be eligible for state-funded social care from £23,520 to £123,000

The government expects these changes will lead to fewer people having to sell their homes in order to pay for their long-term care needs.

Speaking in Parliament, Mr Hunt said that the current system was ‘desperately unfair’ as many older people face ‘limitless, often ruinous’ costs. The minister stated that he wants the country to be ‘one of the best places in the world to grow old’.

The term social care covers a range of services provided to help vulnerable people improve their quality of life and assist them with their day-to-day living.

People often requiring social care include:

• people with chronic (long-term) diseases
• people with disability
• the elderly – particularly those with age-related conditions, such as dementia

Social care services can include:

• healthcare
• equipment
• help in your home or in a care home
• community support and activities
• day centres

Currently, state funding for social care is based on two criteria:

• means – people with assets of more than £23,520 do not qualify for funding
• needs – most local authorities will only fund care for people assessed to have substantial or critical needs

The majority of people currently requiring social care pay for it privately. These are known as ‘self-funders’.

Put simply, on average, the UK population is getting older.

When the welfare state was created in the early 20th century, it was not expected that people would someday routinely live into their 70s, 80s, and even 90s.

The increase in life expectancy is a good thing, however, it brings a new set of challenges.

While people are living longer, they are also spending more of their lives in ill health. Older people are more likely to have potentially complex care needs that can be expensive to manage.

Many people are currently ineligible for state-funded social care under the existing laws. To meet the costs of these care needs, these ‘self-funders’ have, in many cases, had to sell or remortgage their home, or sell other assets to pay for the costs of their care.

Without reforms, experts agree that the cost of social care for both the state (through taxes) and to ‘self-funders’ is likely to become increasingly problematic.

To try and find the best way to resolve some of the difficulties of fairly funding adult social care, the Department of Health set up a commission. This independent commission reported its findings to ministers in July 2011. The government considered these findings in its white paper on care and support published in July 2012, and in the drafting of the proposed new legislation.

The government has introduced a Social Care Bill which will need to be passed by the Houses of Parliament.

If the bill is successfully passed it is expected the amendments will come into force by 2017.

Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links To The Headlines

Social care: Jeremy Hunt hails 'fully-funded solution'. BBC News, February 11 2013

Social care reforms: Almost 2 million pensioners will be denied state help. The Daily Telegraph, February 11 2013

Social care reform: how your family may be affected. The Daily Telegraph, February 11 2013

Dilnot 'regrets' decision to set social care cap at £75,000. The Guardian, February 11 2013

Hunt statement on adult social care cap: Politics live blog. The Guardian, February 11 2013

The introduction of a limit on the number of tablets sold in packets of paracetamol has led to a 43% reduction in the number of poisoning deaths, The Independent has accurately reported. This is one of those relatively rare truly "good news" health stories.

This figure is taken from a useful and reliable piece of research that looked at the long-term impact of restricting the number of tablets in paracetamol packs.

The size of paracetamol packs available over the counter has been limited by law since 1998. This research looked at the number of paracetamol-related deaths and paracetamol-related liver transplants before and after the legislation (1993 to 2009).

Researchers found an overall 43% reduction in the number of paracetamol-related deaths. There was also a 61% reduction in the number of people needing a liver transplant as a result of a paracetamol overdose. Both figures are taken from reliable national data and are statistically significant even when the general decline in the number of suicides is taken into account.

These results suggest that the law has been successful. However, the nature of this study means that it is difficult to conclude that it was the new law that was directly responsible for this decline.

As the researchers conclude, a large number of deaths due to paracetamol overdose occur every year, and further measures are needed to prevent these potentially avoidable deaths.

Where did the story come from?

The study was carried out by researchers from the University of Oxford Centre for Suicide Research and other institutions in the UK and was funded by the National Institute for Health Research. It was published in the peer-reviewed British Medical Journal.

The media report the findings of this research accurately.

In September 1998 the UK government (on advice from the medicines safety watchdog) brought in legislation to restrict the packet size of paracetamol sold over the counter. Packets sold in pharmacies can now contain a maximum of 32 tablets and those sold outside pharmacies can contain no more than 16 tablets.

The law was introduced because of the large number of people taking paracetamol overdoses in suicide attempts, resulting in large numbers of deaths and people needing liver transplants. When paracetamol is broken down by the liver a small amount of a toxic chemical is produced. At normal paracetamol doses the liver is able to break down this chemical. At overdose levels, however, much more of this toxin is produced than the liver is able to break down and the excess toxin causes damage to the liver.

The aim of this observational study was to examine how paracetamol poisoning deaths and demand for liver transplants have changed over time from the early and mid 1990s (prior to the new law) up to 2009 after the legislation was introduced.

This is a valuable study type for examining trends over time, and collecting this sort of data is the only real way to assess the impact of legislation after it has been implemented nationwide.

As with all studies of this type it is difficult to say whether the introduction of the law is the only factor directly responsible for the changes seen as other factors could also be involved (suicide rates in general have been falling since 2000).

The study is able to indicate whether the trends seen are consistent with the law having an effect.

The researchers used data from the Office for National Statistics to look at the number of deaths in England and Wales between 1993 and 2009 that were due to paracetamol poisoning.

This number could include suicides, open verdicts (when it was unclear whether the poisoning was deliberate or accidental) and accidental poisonings. The researchers looked at deaths in people aged 10 years or over. They looked at deaths due to paracetamol alone, or deaths due to single products that contained paracetamol in combination with other medications (such as paracetamol in combination with codeine dihydrocodeine, ibuprofen or aspirin). They looked at whether alcohol was used in combination with paracetamol by those committing suicide.

As another source of information, the researchers looked at all registrations made at all liver transplant units (people being put on the transplant list) in the UK between 1995 and 2000 for liver transplant as a result of paracetamol poisoning. They restricted their analyses to people aged 10 years or over and resident in England or Wales.

The researchers used statistical methods to look at changes in trends over time. Mortality information from the Office for National Statistics and for the transplant units is provided in three-month periods (quarters). The researchers had mortality data for 23 quarters prior to the introduction of legislation and 45 quarters after introduction. They had transplant data for 15 quarters before the new law and 45 after.

The researchers also took into account general trends in non-paracetamol self-poisonings and suicides in England and Wales over this time period. They did this to test whether any changes were just part of general trends or were specific to paracetamol poisoning. The latter would support that it was the legislation having an effect rather than other more general factors. 

Links To The Headlines

Paracetamol poisoning deaths: Introduction of smaller-sized packets leads to 43% reduction. The Independent, February 8 2013

Fall in paracetamol deaths 'linked to pack limits'. BBC News, February 8 2013

Restrictions on paracetamol sales saved 600 people from overdosing since 1998. Daily Mail, February 8 2013

Smaller size paracetamol reduces deaths. ITN News, February 8 2013

Links To Science

Hawton K, Bergen H, Dodd S, et al. Long term effect of reduced pack sizes of paracetamol on poisoning deaths and liver transplant activity in England and Wales: interrupted time series analyses. BMJ. Published online February 7 2013

The Mail Online has asked whether a ‘Star Trek’ style headband could ‘help banish migraines’. The device, worn on the forehead, is a futuristic-looking metallic headband and based on a small study, may indeed be able to help migraine sufferers.

The Mail reports on a well-conducted, if relatively small, trial comparing the effectiveness of a new electrical device for migraine prevention with an identical ‘sham’ device.

The device – known as a supraorbital transcutaneous stimulator or STS – is stuck to the forehead and delivers electrical stimulation to the nerves around the eyes and forehead.

Researchers found that people who wore the device experienced about two fewer migraine days per month – a reduction that was not seen in the sham group. However, differences between the two groups were only slightly significant.

The device also significantly improved the proportion of people who had at least 50% fewer migraines per month. No side effects of the STS treatment were observed, which is potentially significant because many drug treatments of migraine can cause side effects. However, studies in many more people would be needed to confirm that STS definitely caused no side effects.

Overall, this is a well-conducted trial with promising early results.

The study was carried out by researchers from the Headache Research Unit at Liège University and other institutions in Belgium and was funded by the Walloon Region. The devices were provided by the Belgium company, STX-Med. For those readers of a more cyncical bent, it appears that none of the investigators had any financial interest in either the device or STX-Med.

The study was published in the peer-reviewed journal Neurology.

The Mail Online’s reporting of the findings was accurate and representative of this study. However, the appearance of the device pictured and described on the website differs from the image of the device in the research paper.

In the research paper the device was part of an adhesive strip placed on the forehead. However, the images in the Mail story do correspond with images on the manufacturer’s website. It could simply be the case that there are different models or styles of the device.

This was a randomised controlled trial (RCT) testing the safety and effectiveness of a device designed to prevent migraine, compared with a sham device.

The device is called a ‘supraorbital transcutaneous stimulator’ (STS) which is positioned around the forehead and is designed to stimulate the trigeminal nerve through the skin.

The trigeminal nerve is one of the main nerves of the face and has three main branches – the first going into your forehead and around your eyes, the second going into your cheeks, and the third going into your jaw. These nerves transmit sensations from the face to the brain. This device is designed to stimulate the first (ophthalmic) branch of the trigeminal nerve.

Migraine is a severe headache that is often accompanied by nausea and vomiting and an aversion to light and sound. Migraine with aura is when the headache is preceded by neurological symptoms, most often visual symptoms, such as seeing flashing lights.

As the researchers say, stimulating the facial nerves has long been considered potentially beneficial for treating headaches. In an initial pilot study involving 10 people who have migraines, this new STS device was found to be of benefit. This new research followed on from this by conducting a trial in a larger group of people who have migraines.

An RCT comparing the device with an identical sham device is the best way to see if it is safe and effective. However, more research using far more people, over longer periods of time, is needed to properly assess the device’s safety and effectiveness.

The study was conducted in five specialist headache clinics in Belgium. People were eligible for the study if they were adults (aged between 18 and 65 years old) who experienced migraine, with or without aura, and had at least two migraine attacks in the month before the start of the trial.

The researchers excluded people who had taken preventive treatments (such as beta blockers or amitriptyline) for migraine over the past three months, or who in the past had failed to respond to at least three conventional migraine treatments.

The STS device and the sham device were identical. Each consisted of a 30mm by 94mm self-adhesive electrode placed on the forehead, covering the top of the bridge of the nose and above both eyes. The STS delivers electrical impulses over sessions lasting 20 minutes. Both the STS and the sham device buzzed identically during treatment, and instructions for use were the same.

The treatment period was 90 days, with an assessment halfway through at 45 days. Participants filled diaries recording when their headaches occurred and how severe they were. This severity was recorded using a 4-point scale:

• 0 – no pain
• 1 – mild and not interfering with normal daily activities
• 2 – moderate, interfering with daily activities
• 3 – severe pain prohibiting daily activities

Participants were also asked to record whether the migraine was associated with symptoms of aura, nausea/vomiting, or aversion to light or noise and to say whether they used any pain-relieving medication.

The researchers’ main outcome measures were:

• change in monthly migraine days from before the trial to 90 days
• the proportion of people with response as defined by at least 50% reduction in monthly migraine days

Other outcomes included other measures of the headache and participant satisfaction with the device.

The trial included 67 people, 34 in the STS group and 33 in the sham group. The trial was completed by 30 and 29 people respectively, but everyone who started the trial was included in the final statisctical analyses.

By 90 days researchers found that people using the STS device experienced a significant, 30%, reduction in the number of migraine days (from 6.9 days before treatment to 4.9 days after treatment). In the sham group there was a 5% difference in migraine days (from 6.5 before treatment to 6.2 after treatment). However, the actual difference between the two groups was only of borderline clinical significance.

For the other main outcome examined, the STS device significantly improved (by 38%) the proportion of people achieving a response (at least 50% reduction in monthly migraines days). Just 12% of the sham group experienced a >50% reduction in monthly migraines days.

People using the STS device also had fewer total migraine attacks, fewer days with headache, and used fewer pain relief medications each month. However, it did not improve severity of migraines. Satisfaction with treatment was also higher in the STS group (70.6%) than the sham group (39.4%). There were no reported adverse effects in either group.

The researchers conclude that their study provides high-level evidence that treatment with a supraorbital transcutaneous stimulator (STS) is effective and safe as a preventive therapy for migraine.

While this news may seem like something out of science fiction, it appears that there is indeed some cause to think that a device looking similar to that worn by Star Trek’s Geordi La Forge (pictured above) could have the potential to be used by people who have migraines.

This news story is based on a well-designed study that benefits from using identical STS and sham devices. It also benefits from having a high follow-up rate and the fact that neither participants nor investigators were aware of which treatment each person used.

The study demonstrates that the STS had some effect in improving the main outcomes that it set out to examine. It improved the number of migraine days per month, and the proportion of people who responded as defined by at least 50% reduction in monthly migraine days. There was also some benefit on other outcomes and no observed safety effects.

However, further study of this device will be needed to confirm it is safe and effective and to see who would most benefit from treatment.

So far, relatively few migraine sufferers (67) have been studied and the use of the device has only been examined over three months. Longer-term treatment in much larger numbers of people (ideally hundreds or thousands) would be needed to confirm that this device is safe, particularly if it is used daily for long periods of time.

Safety, effectiveness, acceptability, and convenience (particularly considering it is a device worn on the forehead) would also need to be compared to standard medical treatments currently used for migraine prevention.

Overall, this is a well-conducted trial, but more research is needed.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Could this 'Star Trek' headband help banish migraines? Mail Online, February 7 2013

Links To Science

Schoenen J, Vandersmissen B, Jeangette S, et al. Migraine prevention with a supraorbital transcutaneous stimulator – A randomized controlled trial. Neurology. Published online February 6 2013

"Study finds obesity can lead to lack of vitamin D," BBC News has reported.

This fascinating, insightful and accurate BBC story highlights a new danger to add to the list of problems caused by obesity.

The headline is based on a large, complex and broad study investigating the link between obesity and vitamin D levels in the body.

Previous research has suggested a link between vitamin D and obesity. Until now it has been unclear whether obesity caused vitamin D deficiency or whether low levels of vitamin D made people more likely to put on weight.

This research found that people with genetic variations that are known to be associated with obesity had lower levels of vitamin D. Conversely, people with genetic variations linked with lower levels of vitamin D were no more likely to be obese.

This would strongly suggest that obesity causes lower levels of vitamin D, rather than the other way round. The researchers speculate that vitamin D may become ‘trapped’ inside fat tissue so that less of it is available to circulate inside the blood.

Before firm conclusions can be drawn more evidence is needed from different sources that have looked at the effects of BMI on vitamin D levels. A convincing explanation for why this might be the case is also needed.

The study was carried out by a large collaboration of researchers from US and European institutions. It was funded by the British Heart Foundation and the UK Medical Research Council. The study was published in the peer-reviewed medical journal PLOS Medicine.

The BBC News coverage was factually accurate and was particularly helpful because it included a concise summary of complex research. It put the research in context with a quote from Professor David Haslam, from the National Obesity Forum. He said that "food intake and genetics all play a part in obesity – but this research is a reminder that physical activity, like walking the dog or going for a run out in the sunshine, shouldn't be forgotten and can help correct both weight and lack of vitamin D”.

This study combined existing data from genetic studies to investigate the link between vitamin D levels in the body and body mass index (BMI). People with a BMI of 30 or more are considered obese.

The researchers in this study used an approach (known as bi-directional Mendelian randomisation analysis) that can help to establish whether an exposure is causally linked to an outcome of interest. This means it determines whether one thing causes another or whether the association occurs by chance.

This approach aimed to establish whether vitamin D levels caused or were caused by high BMI. It used both physical and genetic measures. The physical measures were BMI and vitamin D levels and the genetic measures were genetic variations associated with vitamin D levels and BMI. 

The researchers hypothesised that if lower vitamin D levels in some way ‘caused’ obesity, a genetic variant associated with lower vitamin concentrations should be associated with BMI. Alternatively, if obesity leads to lower vitamin D status, then genetic variants associated with higher BMI should be related to lower vitamin D concentrations.

Although this type of study can give information about possible causal links, a large body of evidence of different types needs to be accumulated before a firm causal link can be established.

The researchers primarily used information from 21 studies (42,024 adult participants of European ancestry) to establish genetic links between:

• 12 BMI-related genetic variations and BMI
• four vitamin D-related genetic variations and vitamin D levels

For each individual a genetic “score” was generated which indicated the strength of their genetic tendency towards higher BMI or lower vitamin D levels.

Associations between the vitamin D-related genetic variations and BMI were further tested in a group of 123,864 people taking part in the Genetic Investigation of Anthropometric Traits (GIANT) study.

The researchers then pieced the two elements of the study together and performed statistical analysis to test whether the genetic variations associated with BMI and vitamin D levels were linked to either BMI or vitamin D levels in the body.

The statistical analysis made adjustments for some factors that could influence results (potential confounding variables).

The researchers found that:

• Every unit increase in BMI (1kg/m2) was associated with a 1.15% reduction in the level of vitamin D in the blood. This finding was confirmed in a different analysis that showed each 10% increase in BMI score was associated with a 4.2% lower level of vitamin D. The evidence also showed that every point increase in BMI genetic variation score was associated with a small but statistically significant 0.06% decrease in vitamin D concentration.
• The BMI-associated genetic variations were associated with both higher BMI and lower vitamin D levels.
• As the researchers expected, the genetic variations known to be associated with vitamin D levels were strongly associated with vitamin D levels in the body but, crucially, not with BMI.
• No association was seen between vitamin D genetic variation scores and BMI, a finding that was confirmed in the large GIANT study.

Piecing together the complex pieces of the jigsaw above, the authors concluded that their findings suggest that higher BMI could lead to lower vitamin D levels, but that any corresponding effects of vitamin D levels on BMI are likely to be small.

From a public health perspective, they noted that, “population-level interventions to reduce BMI are expected to decrease the prevalence of vitamin D deficiency”.

This complex study used physical and genetic measures to attempt to establish whether there could be a causal link between obesity and lower vitamin D levels in Caucasian individuals.

The study results suggested that it was higher BMI that caused lower vitamin D levels rather than the other way round.

This interesting finding highlights a potential additional benefit of reducing obesity in that it may also reduce the prevalence of vitamin D deficiency.

However, by itself this research cannot prove that higher BMI directly causes lower vitamin D levels. A larger body of different types of evidence, including evidence showing whether reducing BMI can affect vitamin D levels, is needed before firm conclusions can be drawn.

The authors note that vitamin D is stored in fatty tissue, and that “the most likely explanation” for the association is that obese people store more vitamin D in their fat, and have less vitamin D circulating in their blood.

It is important to remember than the main modifiable factors known to influence vitamin D levels are exposure to sunlight and dietary vitamin D intake.

Public health advice remains unchanged – maintaining a healthy weight is beneficial to physical and mental health.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Study finds obesity can 'lead to lack of vitamin D'. BBC News, February 6 2013

Links To Science

Vimaleswaran KS, Berry DJ, Lu C, et al. Causal Relationship between Obesity and Vitamin D Status: Bi-Directional Mendelian Randomization Analysis of Multiple Cohorts. PLoS One Medicine. Published online February 5 2013

"Being generous can give you more than a warm glow... it protects health and helps you live longer," the Mail Online reports. 

The news is based on a study that looked into the effect that being caring has on our physical and mental health. This was analysis of research done in the 1980s and 1990s that looked at the health and lifestyles of older married couples.

As part of the original study, people were asked:

• how much of their time they spent helping others
• whether or not they had recently experienced stressful life events

Researchers traced their risk of dying over a five-year follow-up period. They then assessed the association between caring, stress and subsequent death.

In line with previous studies, the research found that people who experienced stressful events had a higher risk of death. However, people who experienced stressful events and spent time helping others did not have a higher risk of death. The researchers interpreted this as meaning that helping others buffers against the negative impact of stressful life events.

However, the study has considerable limitations that make it difficult to say whether these findings apply to most people and what the precise nature of the relationship is. 

Despite these limitations, the findings do add to our understanding of how helping others might also improve our mental – and possibly physical – wellbeing.

The study was carried out by researchers from the University of Buffalo, Grand Valley State University and Stony Brook University in the US, and was funded by the US National Institute on Aging.

It was published in the peer-reviewed American Journal of Public Health.

The study was covered appropriately, if uncritically, by the Daily Mail.

This research was a secondary analysis of data from a previous prospective cohort study that examined the relationship between providing help and support to others and the risk of dying. The study specifically aimed to determine whether experiencing stressful events changed this relationship.

The original study was carried out between 1987 and 1994. The participants were drawn from the Detroit area in the US. They were all married couples, and in each couple the husband's age was 65 or more. The current study analysed data from just over half of this cohort (846 of the original 1,536). 

Researchers traced their risk of dying over a five-year follow-up period. They assessed the association between caring, stress and subsequent death.

The researchers report that there is a known relationship between social connectedness (the amount of people you interact with in a meaningful way) and health. Over the last two decades, multiple studies have been carried out attempting to describe this relationship more fully.

Research into the link between receiving social support and health or mortality has come up with inconsistent results. The current study turns the relationship on its head and examines whether providing rather than receiving social support is the source of this link. The authors thought that helping others would reduce the association between experiencing stressful events and dying.

This observational research can describe the associations between helping, stress and longevity, but cannot determine whether helping behaviour directly causes changes in the risk of dying.

The researchers used data collected during interviews with 846 married people (423 couples) conducted between 1987 and 1988. The original study, called "Changing Lives of Older Couples", had been designed to study spousal bereavement, but also collected data on a range of other psychological, social and health variables. This means that it is also possible to carry out secondary analysis separate from the original goal of the initial study.

Participants were asked whether they had recently experienced stress or had provided help to their close network of friends and family.

For the purposes of the current analysis, the researchers classified participants as having recent stress if their interviews revealed that during the past year they had experienced:

• serious non-life threatening illness
• burglary
• job loss
• financial difficulties
• death of a family member

To categorise providing help or support to others, the researchers used data on how much time over the past year the participants had spent on any of four specific activities for friends, neighbours or relatives who they did not live with:

• transportation, errands or shopping
• housework
• child care
• other (unspecified) tasks 

The researchers then used previously collected data to determine which of the participants died during the five-year follow-up period. This data was originally collected by scanning obituaries published in one of three local newspapers each day, as well as death records provided by the state of Michigan.

The researchers statistically tested the relationship between helping others, stress and mortality over time. This analysis was intended to determine whether experiencing stress influenced the relationship between helping others and the risk of death.

This analysis included several other variables that could potentially account for or confound the relationship, including demographic and socioeconomic factors, social interactions, self-rated health, health behaviours and mental health.

The average age of the selected group of 846 participants was 71. Overall, 134 people (~16%) died during the follow-up period.

At the beginning of the study, 74% of the sample reported having helped a friend, neighbour or relative, with the average amount of time spent in such activities ranging from 20 to 39 hours over the previous year. These participants were, on average, younger, healthier, of higher socioeconomic status, had more social contact and experienced more social support than people who reported not helping others.

Helping others was found to be predictive of a decreased risk of dying over the five-year follow-up period (hazard ratio [HR] 0.41, 95% confidence interval [CI] 0.29 to 0.57).

Overall, 70% of the participants reported experiencing none of the five stressful life events assessed in the study, while 26% reported experiencing one event, and 4% reported that they experienced two or three events over the previous year. Experiencing a stressful life event was associated with increased mortality over the follow-up period (HR 1.56, 95% CI 1.22 to 1.99).

When the researchers considered the association between helping others and mortality in the context of stressful events, they found that there was a significant interaction between helping and experiencing stress and mortality risk over time, even when controlling for other potentially confounding variables.

Stress was not significantly associated with mortality among individuals who reported helping others (HR 0.96, 95% CI 0.79 to 1.18).

Conversely, among individuals who did not report helping others each additional stressful life event was associated with a 30% increase in the risk of dying during the five-year follow-up period (HR 1.30, 95% CI 1.05 to 1.62).

The researchers report that their study helps "to clarify what kinds of social connections are beneficial and why."

The authors point out that as this is an observational study (as opposed to an experimental design), they cannot rule out the possibility that confounding variables not assessed in this study could explain the observed relationship between helping others, stress and mortality.

They report that they included likely confounding variables, including "health and functioning, health behaviours, psychological well-being, personality traits, and social engagement and received social support" in their analyses.

The researchers concluded that, "helping valued others predicts reduced mortality specifically because it buffers the association between stress and mortality."

This study suggests that helping others is associated with a decreased risk of dying. Looking at the role of providing support to others is an interesting approach to examining the relationship between social connectedness with health and longevity.

At the risk of being ungenerous, however, this study has several weaknesses that should be considered. A major drawback is the fact that variables such as health and functioning, social engagement and psychological wellbeing were measured on a subjective, self-reported basis.

While it is important that the interviews included questions related to health and wellbeing, there is always a risk that subjective measures do not completely or accurately measure the variables of interest.

This is especially important, as the type of helping behaviours measured in this study were all considered "tangible aid" that require a degree of physical functioning and ability. Providing assistance with transportation, errands, shopping, housework or childcare may be less likely among people with mobility issues or health problems.

This doesn't necessarily mean that people with mobility issues or health problems can't or don't provide social support, just that they may find it more difficult to provide the specific types of support measured in this study.

There is a risk that focusing on tangible aid doesn't take into account other means of social and physical support that people provide. The researchers note this limitation and say that, "it is possible that expressing warmth and caring or emotional support" (for example, via a phone call or friendly email) is also beneficial.

The study also only assessed the support provided to people that did not live with the participants, which does not include any help given to spouses or ill relatives living in the same home. Again, this may have failed to encapsulate important sources of helping behaviour.

It is also important to note that this study was conducted among a very specific population: older married couples. We should therefore not assume that we can apply the results to people of all ages, and they may also not be applicable to non-married couples.

Finally, as the data from this study was collected in the US 25 years ago, it is worth considering whether the results apply in today's Britain.

Despite these limitations, this is an interesting study that provides something of an insight into an often neglected field of research – whether altruistic behaviour also brings individual benefits.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Being generous can give you more than a warm glow... scientists say it protects health and helps you live longer. Daily Mail, February 6 2013

Links To Science

Poulin MJ, Brown SL, Dillard AJ, Smith DM. Giving to Others and the Association Between Stress and Mortality. American Journal of Public Health. Published online January 17 2013

Most of the UK media has reported on the Francis inquiry into significant failures in care at the Mid Staffordshire NHS Foundation Trust.

The report suggests a raft of radical changes to help improve patient safety. These include proposals to make serious but avoidable medical mistakes a criminal offence.

The Healthcare Commission (the hospital regulator at the time) first raised concerns about the trust in 2007, after determining it had unusually high death rates.

These concerns led to a series of reports, undertaken by different bodies, which all found widespread evidence of significant failures in care, including:

• patients being left in soiled bedding
• patients not given ready access to food and water
• chronic staff shortages
• failure in the leadership of the hospital
• a culture in which staff members who had concerns about failures in care were discouraged from speaking out

This current inquiry was commissioned in 2010 to investigate wider issues that may have contributed towards these serious problems. The inquiry, carried out by the barrister Robert Francis QC, was asked to come up with recommendations which could help prevent similar failings from happening in the future.

The findings of the inquiry have now been published.

What were the main findings of the inquiry?

The findings of the inquiry can fairly be described as damning. It highlights what amounts to a ‘perfect storm’ of systematic failures of care at multiple levels, including:

• a ‘Somebody Else's Problem’ attitude among hospital staff – perceived problems were too often assumed to be the responsibility of others
• an institutional culture that cared more about the needs of the hospital staff than the patients
• an unacceptable willingness to tolerate poor standards of patient care
• a failure to accept and respond to legitimate complaints
• a failure of different teams within the hospital, as well as in the wider community, to communicate and share their concerns
• a failure of leadership – in particular, financial changes needed to achieve Foundation Trust status were seen, by the inquiry, to take precedence over patient care  

Mr Francis concludes that, ‘The extent of the failure of the system shown in this report suggests that a fundamental culture change is needed. This does not require a root and branch reorganisation – the system has had many of those – but it requires changes which can largely be implemented within the system that has now been created by the new reforms.’

The inquiry makes a total of 290 individual recommendations. These include:

• causing harm or death to a patient due to avoidable failures in care should be a dealt with as a criminal offence (rather than a regulatory or civil matter)
• NHS staff, including doctors and nurses, should have a legal ‘duty of candour’ – so they are obliged to be honest, open and truthful in all their dealings with patients and the public
• a single regulator of both quality of care and financial matters should be created
• non-disclosure agreements (‘gagging orders’) – where NHS staff agree not to discuss certain matters – should be banned
• there should be a ‘fit and proper’ test for hospital directors, similar to those set for football club directors
• a clear line of leadership needs to be established, so it is always clear who is ultimately ‘in charge’ when it comes to a particular patient
• uniforms and titles of healthcare support workers should be clearly distinguished from those of registered nurses

The final report of the public inquiry has now been published, and the government has said it will respond to the recommendations of the inquiry in March 2013. Changes required by earlier reports into the failings at Mid Staffs are already underway.

The Prime Minister David Cameron has said that “quality of care” should be on a par with “quality of treatment”.

He said: “We have set this out explicitly in the Mandate to the NHS Commissioning Board, together with a new vision for compassionate nursing.

“We have introduced a tough new programme for tracking and eliminating falls, pressure sores and hospital infections.

“And we have demanded nursing rounds every hour, in every ward of every hospital.”

Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links To The Headlines

Stafford Hospital: Hiding mistakes 'should be criminal offence'. BBC News, February 6 2013

Mid Staffordshire NHS trust inquiry report published. The Guardian, February 6 2013

David Cameron apologises for Mid Staffs scandal after damning report. The Daily Telegraph, February 6 2013

Medical staff must face criminal charges for failures, says care scandal report. The Independent, February 6 2013

The new tuberculosis vaccine MVA85A has been found to be less effective than initially thought, prompting widespread consternation in the press. The Daily Mail reported that the vaccine "does little to protect children", while BBC News and The Guardian said hopes for the vaccine had been "dashed". Although the stories are based on solid science, the news is actually less worrying than the headlines suggest.

The reports are based on an early trial of a booster vaccine that researchers hope might help improve the effectiveness of the existing BCG vaccine. Although the BCG is effective in the UK, new vaccines and boosters are needed as it is less effective in countries with a high burden of tuberculosis (TB).

The research focused on the safety and effectiveness of the vaccine, which had previously shown much promise. Despite the disappointing results, researchers hope to test the vaccine further on different populations, which may be more successful. 

Progress in medical knowledge is not just based on success stories – failures also add to a greater scientific understanding. Although the results of this trial of MVA85A may be disappointing, they will feed back into the development of new vaccines against tuberculosis. 

The study was carried out by researchers from South Africa, the US and the UK. It was funded by Aeras, the Wellcome Trust and the Oxford-Emergent Tuberculosis Consortium (OETC) Ltd. Aeras is a non-profit product development organisation dedicated to the development of products to prevent tuberculosis. The Oxford-Emergent Tuberculosis Consortium is a joint venture between the University of Oxford and Emergent BioSolutions Inc.

It was published in the peer-reviewed medical journal The Lancet.

The research was covered well by BBC News, The Guardian and The Independent.

A randomised controlled trial was performed to assess the safety and efficacy of a new tuberculosis vaccine, comparing the vaccine with a placebo.

This is the ideal type of study design to address this question.

The researchers enrolled 2,797 healthy infants aged between four and six months from a rural region near Cape Town, South Africa.

All of the infants had previously received the BCG vaccine. They were randomised to receive either the new tuberculosis vaccine MVA85A (1,399 children) or a placebo that consisted of a candida skin test antigen (1,398 children).

The researchers wanted to see if the vaccine was safe by monitoring the incidence of adverse and serious adverse events in all vaccinated infants. They also looked at whether the vaccine could prevent tuberculosis in children who had received at least one dose of either the placebo or the MVA85A vaccine who had not deviated from the study protocol.

The infants were followed for 24.6 months on average. In that time, more infants who had the MVA85A tuberculosis vaccine had adverse events than infants who received the placebo (89% had at least one adverse event in the vaccine group, compared with 45% in the placebo group).

However, the number of children who had adverse events that affected their whole body (systemic) or who had serious adverse events was similar for the two groups, and none of the serious adverse events was related to MVA85A.

Thirty-two infants in the MVA85A tuberculosis vaccine group developed tuberculosis, compared with 39 infants in the placebo group. The efficacy of MVA85A against tuberculosis was not statistically different to the placebo as the slightly lower rate of tuberculosis in the vaccine group could have been the result of chance.

The researchers wanted to see how many children were infected with M. tuberculosis, the bacteria responsible for most cases of tuberculosis, even if they did not have any symptoms.

They found that 178 children (13%) who received the MVA85A vaccine were infected with the bacteria, compared with 171 (12%) children who received the placebo. Again, this was not a statistically different result.

The researchers found that the MVA85A vaccine was safe and there was some evidence that it stimulated an immune response. However, they could not explain why the MVA85A vaccine did not provide protection against the M. tuberculosis infection or tuberculosis.

They state that the reasons for this need to be explored and that, "Information gained from the successful execution of this study will aid the planning of future trials and vaccination strategies. Substantial global efforts to develop an improved vaccine against tuberculosis must continue".

The effectiveness of the BCG against tuberculosis is variable and has been found to be less effective in countries such as South Africa, where as many as 1% of the population has TB. An effective booster vaccine would therefore be useful.

Although this study found the new vaccine is safe, it does not appear to have performed better than the placebo in children who had already had the BCG vaccine when the researchers looked at:

• how well the vaccine prevented initial infection with the bacterium responsible for tuberculosis
• the ability of the vaccine to prevent TB developing once infection had taken place (as people can contract TB bacteria without developing symptoms)

Despite this setback, several further lines of investigation are being pursued by researchers. They now want to look at whether the MVA85A vaccine might work better in other sub-populations, and whether it might improve protection against pulmonary tuberculosis (a type of lung infection caused by the M. tuberculosis bacteria) in people who have HIV, for example.

Other TB vaccines are in development, and the knowledge gained during this study will be useful. The researchers also collected samples assessing immune response to the vaccine, and these may be useful to determine what sort of response is required for protection against TB.

Although the results of the effectiveness of MVA85A in this trial may be disappointing, the findings are sure to help the future development of vaccines against tuberculosis.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. 

Links To The Headlines

Tuberculosis vaccine hopes dashed. BBC News, February 4 2013

Hopes for new TB vaccine dashed following unsuccessful trials. The Guardian, February 4 2013

Disappointment for British researchers as new TB vaccine 'does little to protect children'. The Independent, February 4 2013

Links To Science

Tameris MD, Hatherill M, Landry BS, et al. Safety and efficacy of MVA85A, a new tuberculosis vaccine, in infants previously vaccinated with BCG: a randomised, placebo-controlled phase 2b trial. The Lancet. Published online February 4 2013

Commentary

Dye C, Fine REM. A major event for new tuberculosis vaccines. The Lancet. Published online February 4 2013

A study published today in the British Medical Journal finds that people who followed health advice and ate certain omega-6 polyunsaturated fats instead of animal fats had higher death rates. This study has prompted media comment as it appears to contradict established health guidance. Polyunsaturated fats are commonly used in "healthy" margarines, spreads and other alternatives to butter.

However, experts say that we should not be unduly alarmed. The Science Media Centre has issued a statement that says that the research, "does not alter our understanding of the possible relationship between diet and cardiovascular risk" and that "the claims in the paper are not new or at odds with existing evidence".

There's a danger of over-interpreting this research. It focused on one, not all, omega-6 polyunsaturated fats, and the results are in a very specific group – middle-aged men who had had heart attacks.

The study suggests that not all polyunsaturated fatty acids are good for the heart. But British consumers should not panic – the safflower oil used as a source of omega-6 in this study is rarely used in this country.

The study was carried out by researchers in the US and Australia. It was funded by the Life Insurance Medical Research Fund of Australia and New Zealand and the Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health.

The study was published in the peer-reviewed British Medical Journal.

This was a second analysis of a randomised controlled trial performed in Australia between 1966 and 1973. A randomised controlled trial is the ideal trial design to examine cause and effect. However, the current analysis includes outcomes that were not primary outcomes of the original trial.  

The original trial investigated whether replacing sources of saturated fats, such as animal fats and butter, with safflower oil (a kind of oil used for cooking and in some manufactured foods) reduced the risk of death from any cause in men with premature coronary heart disease. It only reported the risk of death from all causes and deaths due to cardiovascular disease (CVD) or coronary heart disease (CHD) were not examined.

In this new study, the researchers calculated whether eating more safflower oil affected the risk of death in people with cardiovascular or coronary heart disease (this is called "secondary prevention"). The researchers also wanted to know to what extent an increased intake of polyunsaturated fatty acids or saturated fatty acids was associated with deaths from CVD or CHD. The results of this new analysis were then used to update a meta-analysis of other trials looking at polyunsaturated fatty acids for cardiovascular risk reduction.

Researchers recruited 458 men aged between 30 and 59 who had suffered a heart attack or an episode of coronary insufficiency or angina after admission to hospital. These men were randomised to receive either a dietary intervention or no specific dietary instruction, in addition to standard medical care.

The dietary intervention consisted of instructions to:

• increase polyunsaturated fatty acid intake to about 15% of total energy intake
• reduce saturated fatty acid intake to less than 10% of energy intake
• reduce cholesterol to less than 300mg per day

To help achieve these targets, the men were given liquid safflower oil and safflower oil polyunsaturated margarine. They were told to use these items to replace animal fats, butter and margarine, shortenings, cooking oils and salad dressing, as well as taking safflower oil as a supplement. Safflower oil contains 74.6g per 100g of a type of polyunsaturated fat called omega-6 linoleic acid, and no other polyunsaturated fatty acids.

Men returned for clinical assessment every three months for the first year and then every six months for a median of 39 months. Blood samples were taken to measure the levels of cholesterol and triglyceride (fat). The men also filled in a food diary so that their diet could be assessed.

Deaths that occurred during the trial were assigned codes from the International Classification of Diseases (ICD), according to information taken from death certificates of final hospital admission records. Using survival analysis, the researchers analysed whether the risk of death from any cause or deaths from cardiovascular and coronary heart disease differed between the intervention and the control group. The researchers also examined whether nutrient intake (based on the results of the food diaries) accounted for changes in mortality.

• men in the intervention group significantly increased their intake of polyunsaturated fatty acids, and significantly reduced their intake of saturated fatty acids, cholesterol and mono-unsaturated fatty acids compared with the control group
• the level of cholesterol in the blood decreased significantly more for men in the dietary intervention group compared with the control group, although changes in the level of triglycerides (fats) in the blood, body mass index (BMI) and blood pressure were similar between groups
• men in the dietary intervention group had higher rates of deaths from any cause than controls (17.6% of the dietary intervention group died compared with 11.8% of the no intervention group, hazard ratio 1.62, 95% confidence interval 1.00 to 2.64)
• men in the dietary intervention group had higher rates of death from cardiovascular disease (17.2% of the dietary intervention group died due to cardiovascular disease compared with 11.0% of the no intervention group, hazard ratio 1.70, 95% confidence interval 1.03 to 2.80)
• men in the dietary intervention group had higher rates of deaths from coronary heart disease (16.3% of the dietary intervention group died due to coronary heart disease compared with 10.1% of the no intervention group, hazard ratio 1.74, 95% confidence interval 1.04 to 2.92)
• an increase in 5% of food energy from omega-6 linoleic acid predicted a 35% higher risk of cardiovascular death and a 29% increase in all-cause mortality in the intervention group

When these results were added to a meta-analysis of other trials that have assessed the effects of linoleic acid, it was found that linoleic acid increased the risk of death from coronary heart disease and cardiovascular disease, although these results were not significant.

The researchers have concluded that there is no clear clinical evidence that the most common polyunsaturated fatty acid, omega-6 linoleic acid, can reduce people's risk of developing heart conditions. "Advice to substitute polyunsaturated fats for saturated fats is a key component of worldwide dietary guidelines for coronary heart disease risk reduction. However, clinical benefits of the most abundant polyunsaturated fatty acid, omega-6 linoleic acid, have not been established.

"In this cohort, substituting dietary linoleic acid in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease. An updated meta-analysis of linoleic acid intervention trials showed no evidence of cardiovascular benefit.

"These findings could have important implications for worldwide dietary advice to substitute omega 6 linoleic acid, or polyunsaturated fats in general, for saturated fats."

Contrary to received wisdom, this research suggests that not all polyunsaturated fatty acids are good for the heart (the so-called "cardioprotective effect").

This study has several strengths. It was a randomised controlled trial, using just one type of oil to increase consumption of polyunsaturated fatty acids.

However, the study also has its limitations. The dietary data collected during the original trial does not contain enough information to rule out the possibility that changes in other nutrients could have caused the effect seen.

In this trial, participants were advised to increase their intake of polyunsaturated fatty acids, mainly from omega 6-linoleic acid, to 15% of total food energy, and the results may not be generalisable to lower linoleic acid intakes.

As this trial was performed on men aged between 30 and 59 who had premature coronary heart disease, it may not be possible to generalise the results to men who do not have coronary heart disease, men of different ages, and women.

It is worth noting that vegetable oils have very different characteristics in terms of the proportions of omega-3 or omega-6 content and the types of polyunsaturated, monounsaturated and saturated fatty acids that they contain. Oleic acid and linoleic acid are likely to have different properties to linoleic acid, and so it cannot be assumed any effect seen here is typical of all vegetable oils.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Start spreading the news - saturated fat 'is not so bad,' says study. The Independent, February 5 2013

Heart attack risk in 'healthy spreads'. Daily Express, February 6 2013

Swapping the butter for margarine 'may be
bad for your health'. U.S. scientists claim polyunsaturated fat 'doubles heart risk'. Daily Mail, February 6 2013

Links To Science

Ramsden CE, Zamora D, Leelarthaepin B, et al.  Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. BMJ. Published online February 6 2013

Editorial
Calder PC. Old study sheds new light on the fatty acids and cardiovascular health debate. BMJ. Published online February 5 2013

Lazy men who spend hours watching TV could be halving their sperm count, according to a number of newspapers.

While the reports are based on proper medical research, the link between exercise and sperm count is not definitively proven.

What’s more, a man’s ability to have children is not just based on his sperm count. Male infertility problems are often complex and in many cases may not be solved by simply changing lifestyle.

The story comes from a study which found that more physical activity and less TV viewing were associated with significantly higher sperm counts.

While the results sound like yet another good reason for male couch potatoes to get more active, it is possible, for example, that an underlying factor affects how much exercise men do and their sperm counts.

The study was carried out by researchers from several US medical schools, the University of Murcia, Spain and the University of Copenhagen, Denmark. It was funded by the National Institutes for Health in the US and the European Union.

The study was published in the peer-reviewed British Journal of Sports Medicine.

The study was reported uncritically in the Metro. The BBC and the Guardian both gave fuller accounts, including comments from independent experts.

This was a cross-sectional study that looked at the relationship between semen quality and men’s levels of physical activity and TV watching. Semen quality is assessed by looking at sperm concentration (this is the concentration of sperm in the ejaculate, also known as sperm count), shape, movement and total sperm count (the total numbers of sperm in an ejaculate).

However, the cross-sectional design of this study means it cannot prove that physical activity and TV viewing levels directly influence sperm quality. This type of study looks at all data at the same moment in time, so it cannot be used to conclude that one thing follows another.

The authors say that semen quality seems to have declined in the past decades, but the reasons for this are uncertain. One possible reason could be the decrease in physical activity and increase in sedentary behaviour that has occurred over the same period. They also point out that strenuous, high-intensity exercise has been linked to male infertility, but the association between moderate exercise and semen quality has yet to be evaluated. The researchers add there is little research into the effects of TV watching on semen quality.

Researchers recruited 222 men, aged 18 to 22 years, from a larger study that took place between 2009 and 2010. The men were asked in a questionnaire about both their physical activity and TV watching in the previous three months. Their semen quality was assessed by sperm concentration, movement, shape and total sperm count.

The men were asked to report the number of hours spent in a normal week doing vigorous, moderate or mild exercise. Researchers wanted to know in particular about the number of hours per week of moderate-to-vigorous physical activity, defined as any exercise which “made you somewhat to very winded or sweaty”.

TV viewing was assessed in the same questionnaire by asking men to select the category of TV watching time per workday or weekend day that corresponded to their average habits over the past three months. TV watching time was categorised as:

• none/almost none
• 1-3 hours daily
• 4-6 hours daily
• 7-9 hours daily
• over 10 hours daily

From this, the researchers analysed the average amount of time spent watching TV each week.

Semen samples were collected by masturbation at a clinic, the men were asked to abstain from ejaculation for at least 48 hours beforehand. The samples were duplicated and analysed in the laboratory within 30 minutes of collection, using accepted criteria for sperm concentration, movement, shape, and total sperm count.

Each participant was also physically examined, including assessment of weight, height, size of testicles and whether they had any genital abnormalities. The men also completed questionnaires on their backgrounds, income, medical and reproductive history, psychological stress, use of medication, smoking habits, and calorie intake.

Researchers classified the men into four groups (quartiles) according to their average moderate-to-vigorous physical activity and their TV watching per week. The association between these two factors and semen quality was evaluated using standard statistical methods. The researchers adjusted their results to take account of potential confounders such as race, smoking habits, body mass index, and calorie intake.

Of the 222 men recruited, 189 completed the study. Researchers found that:

• sperm concentration and total sperm count were directly related to physical activity (p-trend=0.01 and 0.04)
• men in the highest quartile of moderate-to-vigorous activity (15 hours a week or more) had a 73% (95% confidence interval 15% to 160%) higher sperm concentration than men in the lowest quartile (less than five hours a week)
• TV watching was associated with sperm concentration and total sperm count (p-trend=0.05 and 0.06)
• men in the highest quartile of TV watching (more than 20 hours a week) had 44% (95% confidence interval 15 to 63%) lower sperm concentration than men in the lowest quartile (0 hours per week)
• neither physical activity nor TV watching were associated with sperm movement or shape

The researchers say their findings suggest a more physically active lifestyle may improve semen quality. They also say that, unlike the results of previous studies, they found no detrimental effects on semen of very high levels of physical activity such as cycling and long-distance running. However, these effects may be specific to certain exercises such as cycling and long-distance running, with most of the highly active men in this study more likely play football and other sports.

The researchers say the association between TV watching and sperm count needs further research. Previous studies have suggested an association between sperm quality, sedentary activity and temperature of the testicles. However, in this study it was difficult to disentangle the effects of obesity from that of inactivity.

As the authors point out, this small, cross-sectional study cannot prove that more exercise and less TV will improve sperm counts in men. All it provides is a snapshot of the semen quality and the levels of physical activity and TV watching in a small group of young men, at one point in time.

It’s possible that other risk factors (called confounders) may have affected the results, although researchers tried to adjust their results for several of these. Many other factors may be involved in semen quality, including weight, smoking habits, diet, and genetics.

Also, as the researchers point out, it is unclear if the differences in sperm counts translate into clinically relevant differences in fertility. Sperm count is only one analysis performed to measure male fertility.

This type of study relied on men self-reporting both exercise levels and TV watching, which could have affected the reliability of its results.

The authors also say that the small sample size means that the results could have been due to chance. It’s worth noting that the confidence levels given in the results are very wide, which indicates the results may not be reliable. For example, men in the highest quartile of moderate-to-vigorous activity had from 15% to 160% higher sperm concentration.

It would be nice to know if a more active lifestyle had the bonus effect of increasing sperm counts as well as being good for health overall, but this research alone does not provide a definitive answer and should be seen in the context of other studies.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Watching TV for too long 'cuts male fertility by half'. Study shows laziness leads to a drop in sperm quality. Daily Mail, February 5 2013

Men’s fertility halved by hours in front of TV. The Times, February 5 2013 (paywalled site)

Get up and about to help boost your sperm count. Metro, February 5 2013

Active men have higher sperm counts than couch potatoes watching TV. The Guardian, February 5 2013

Prolonged TV viewing linked to lower sperm count. BBC News, February 5 2013

Links To Science

Gaskins AJ, Mendiola J, Afeiche M, et al. Physical activity and television watching in relation to semen quality in young men. British Journal of Sports Medicine. Published online February 4 2013

There has been a dramatic fall in the number of children diagnosed with epilepsy over the last decade, according to a new study reported on by BBC News.

The report is based on an impressive piece of research looking at GP records to see whether the rates of children being diagnosed or treated with epilepsy have changed over time.

It found both the number of children with epilepsy by five years of age, and the annual rate of identification of new cases fell over time.

Overall, the number of children born between 2003 and 2005 who were treated for epilepsy by the age of five was a third less than children born around a decade earlier (specifically born between 1994 and 1996).

One theory to explain this drop in cases is that clinicians have got better at diagnosing epilepsy, so less children are being misdiagnosed with the condition.

Another theory is that the introduction of the meningitis C vaccine in 1999 may also be partially responsible – serious brain infections are a significant risk factor for childhood epilepsy.

Whatever the reasons for the change, this well-conducted study suggests the welcome news that the incidence childhood epilepsy in the UK is receding. 

The study was carried out by researchers from University College London, Great Ormond Street Hospital, Young Epilepsy, the University of Edinburgh, and Paddington Green Health Centre. It was funded by the National Institute of Health Research and the Medical Research Council.

The study was published in the peer-reviewed Archives of Disease in Childhood.

This story was well covered by BBC News.

This was a cohort study using data from The Health Improvement Network, a database with a representative sample of approximately 5% of the UK population.

It aimed to examine trends over time in the incidence (number of new cases over a certain period) of epilepsy recorded in the UK among children aged between 0 and 14 years who had been born between 1994 and 2008. The researchers also looked at how trends varied with sociodemographic factors such as age, gender, and social deprivation.

A cohort study is the ideal study design to examine trends in diagnosis rates. However, in this case it cannot tell us why the number of children with epilepsy has fallen.

The researchers identified cases of epilepsy recorded in primary care (by local doctors and nurses) among 344,718 children aged 14 years old and under who were born between 1994 and 2008.

Children were followed up until the end of 2008, they transferred to another practice, or they died,  resulting in 1,447,760 years of follow-up in total (4.3 years per child on average).

The researchers identified cases of epilepsy based on treatment, clinical diagnosis or symptomatic presentations recorded in primary care medical records.

The researchers also examined a ‘subcohort’ of this cohort: children aged seven years and under between 2001 and 2008.

Over the whole course of the study, 0.38% of children had epilepsy by five years of age based on repeat prescriptions for anti-epilepsy drugs.

If children who had been diagnosed clinically or who had experienced symptoms of epilepsy were also included, 0.68% of children had epilepsy. This is because not every child with symptoms of epilepsy such as non-febrile seizures is diagnosed with epilepsy, and not every child diagnosed with epilepsy is automatically treated with anti-epilepsy drugs, such treatment decisions are made on a case-by-case basis.

The number of children with epilepsy by the age of five declined over time: 1% of children born between 1994 and 1996 had had a repeat prescription for anti-epilepsy drugs, had been diagnosed clinically, or had had symptoms of epilepsy by five years of age. However, the figure dropped to 0.53% for children born between 2003 and 2005, a decline of 47%. This decline was 33% over the same period, if only in children with repeat prescriptions for anti-epilepsy drugs were considered. 

In children aged up to seven years between 2001 and 2008, there were between 71 and 116 cases of epilepsy per 100,000 person years at-risk. However, this figure depends on how epilepsy was defined, it was:

• 71 per 100,000 person years at-risk if epilepsy was defined as having repeat prescriptions for anti-epilepsy drugs, and
• 116 per 100,000 if being diagnosed clinically or having symptoms of epilepsy were also included

In other words, if 100,000 children aged up to seven were followed for one year, between 71 and 116 cases of epilepsy would be expected. The rate of diagnoses was higher in babies aged less than one year than in children aged between one and seven. Rates of epilepsy diagnoses were also higher in boys, and in children from more deprived backgrounds, although the relationship between deprivation and the rate of new diagnoses of epilepsy was not linear.

The number of new cases of epilepsy declined over time. After adjusting for age, gender and deprivation, the number of repeat prescriptions for anti-epilepsy drugs fell by 4% each year after 2001. In addition, the number of children receiving repeat prescriptions, being diagnosed clinically or having symptoms of epilepsy fell by 9% each year.

The researchers conclude that, “the decline since the mid-1990s in epilepsy recorded in primary care may be due to more specific diagnosis, cessation of treatment for some forms of epilepsy, reduced exposure to risk factors or all of these factors”.

This study has found that the number of cases of childhood epilepsy has fallen over time. This was observed when both the number of children with epilepsy by five years of age and the number of children diagnosed with or displaying symptoms of epilepsy per year were considered.

The researchers report that this decline in childhood epilepsy has also been observed in other European countries.

The reasons for this decline are unclear, but may be due to:

• improved diagnostic accuracy
• changes in treatment practices, so that some milder forms of epilepsy are no longer treated and therefore may not have been identified in this study
• changes in environmental exposures; for example, the introduction of the meningitis C vaccine has led to a fall in the rates of infections of the central nervous system (brain and spinal cord)
• there is also reported to have been a decline in the rates of hospital admissions due to traumatic brain injury among children over the past 15 years – another risk factor associated with epilepsy

Overall, as the researchers say, it is unlikely that any single factor could have caused the decline, and it is more likely the case that a combination of factors – environmental factors in addition to changes in drug prescribing practices and more accurate diagnostic techniques – may account for the trend seen.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

'Steep decline' in child epilepsy. BBC News, February 3 2013

Links To Science

Meeraus WH, Petersen I, Chin RF, et al. Childhood epilepsy recorded in primary care in the UK. Archives of Disease in Childhood. Published online January 23 2013

The news that chewing gum could potentially boost brain power has hit the headlines. Both the Daily Mail and the Daily Express covered the story, with the Mail reporting that, "Chomping on gum is good for the brain and can boost alertness by 10%."

However, this claim is based on what is actually a very small study involving just 17 healthy young adults. Such a small sample size means that the results of the study need to be viewed with caution.

Most of us can walk and chew gum at the same time. This study does not prove that gum chewing will help us think any faster. 

The study was carried out by researchers from the National Institute of Radiological Sciences (NIRS) and other academic research centres in Japan. It received funding from the Japanese Ministry of Education, Culture, Sports, Science and Technology, and by Research Fellowships for Young Scientists from the Japan Society for the Promotion of Science (JSPS).

It was published in the peer-reviewed medical journal, Brain and Cognition. 

The study was covered reasonably by the Daily Express and the Daily Mail, although neither reports that such a small number of people (17) were included.

This was an experimental study looking at whether chewing has an effect on attention and cognitive processing speed (the ability to think quickly).

The researchers say that other studies have found varying results when exploring the link between chewing and cognitive functions such as attention.

The study was carried out in a research laboratory under controlled conditions, carrying out very specific tasks.  

The researchers enrolled 19 healthy adults, aged 20 to 34 years. Two of the volunteers were not included in the analysis because they had moved during functional MRI (fMRI) scanning.

Volunteers were asked to perform a cognitive task that involved watching a computer screen that flashed images of a row of five arrows pointing either left or right. Sometimes all of the arrows pointed in one direction and sometimes they pointed in mixed directions.

The volunteers had to press a button with their left or right thumb depending on the direction the middle arrow pointed. In some cases, a central "cue" marker was shown before the arrows appeared to warn the volunteer that the arrows were coming.

The volunteers performed this task both while chewing gum and not chewing gum, with researchers recording the speed and accuracy of the button presses. During the chewing phase, messages on the computer screen instructed volunteers to chew for 10 seconds every six images, just before the test.

The volunteers' brains were monitored using functional MRI (fMRI) while they performed the tasks. This technique shows blood flow in the brain, with increased blood flow indicating more activity in a specific region of the brain.

The researchers assessed whether reaction time and accuracy differed when chewing gum. They also assessed whether there were any differences in brain activity during the chewing and non-chewing tasks.

The researchers had mixed results in the fMRI analysis, with some areas of the brain thought to be involved in alertness and movement becoming more active, while others did not.

They found that chewing did cause some areas of the brain, such as the anterior cingulate cortex, to become more active, but the overall results were inconclusive. Some areas of the brain also associated with alertness actually became less active during chewing.

A similar inconclusive pattern was found when fMRI was used to study areas of the brain involved in "executive function" (in this case, working out which direction the arrow pointed in).

They also found that reaction time was quicker when a person was chewing gum, but their accuracy did not change.

The researchers concluded that chewing reduced reaction time in their cognitive test. The brain scan results suggest that this could be due to increased alertness and an effect on movement control.

They also suggest that chewing gum could possibly make volunteers more relaxed, which could improve alertness and reaction time.

This study has suggested that chewing gum may improve reaction times in healthy adults in a specific computerised cognitive task. The study only assessed 17 healthy relatively young adults, and the results may not apply to other groups of people.

Most importantly, this specially designed cognitive experiment was performed in a laboratory environment, and may not represent what would happen in a real-world setting. For example, we can't say for certain whether people's reaction speeds when driving a car would be improved by chewing gum.

The study may be of interest to some researchers, but at the moment it does not have any obvious practical implications for people's health or day-to-day lives.

A final word of advice: if you do choose to chew, make sure your gum is sugar-free, which is the healthiest option for your teeth.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Chewing over a problem? Chomping on gum is good for the brain and can boost alertness by 10%. Daily Mail, February 3 2013

Something to chew on... gum boosts your brain. Daily Express, February 4 2013

Links To Science

Hirano Y, Obata T, Takahashi H, et al. Effects of chewing on cognitive processing speed. Brain and Cognition. Published online January 29 2013

Short bursts of exercise, such as raking the lawn and climbing the stairs, are an excellent way of warding off health problems such as high blood pressure, high cholesterol and diabetes, the Daily Mirror and many global media outlets reported.

The news is based on the results of a cross-sectional study which suggested that even less than 10 minutes of moderate or vigorous activity, such as climbing stairs, ‘count’ and may be as beneficial as longer periods of exercise.

This useful and well-conducted study measured the physical activity of more than 6,000 adults, in addition to measuring various health markers such as blood fats, blood sugar and blood pressure, that are known to be risk factors for chronic conditions including diabetes and heart disease.

The study found that performing moderate or vigorous activity of any duration – either short bursts of less than 10 minutes or for longer – was associated with improved measurements of several cardiovascular risk factors.

The study suggests that even people who do not have time to go to the gym or an exercise class can get many of the health benefits of exercise from adopting an ‘active’ lifestyle.

While the study cannot directly prove cause and effect, it would suggest that any moderate or vigorous exercise you can fit in during the course of a day, benefits your health.

Where did the story come from?

The study was carried out by researchers from Bellarmine University and Oregon State University. The source of funding for this study was not declared.

The study was published in the peer-reviewed American Journal of Health Promotion.

This study was covered by the Daily Mirror and the Mail Online. Although the gist of the story is correct, the researchers looked at short bursts of moderate and vigorous physical activity, rather than the ‘light exercise’ reported in the Daily Mirror and the Mail Online.

Links To The Headlines

Well, I'll go to the foot of the stairs! Light exercise around the house is as good for your heart as workout. Daily Mirror, January 31 2013

Forget the gym and try the stairs! Short bursts of exercise are just as beneficial as a regular workout. Daily Mail, January 31 2013

Taking the Stairs, Raking Leaves May Have Same Health Benefits as a Trip to the Gym. Sciencedaily.com, published online January 28 2013

Links To Science

Loprinzi PD, Cardinal BJ. Association Between Biologic Outcomes and Objectively Measured Physical Activity Accumulated in >10-Minute Bouts and <10-Minute Bouts. American Journal of Health Promotion. Published online January 2013

Boys as well as girls should receive the HPV vaccine, say experts, it was reported by the BBC and others today. The experts, gathered together by the Throat Cancer Foundation, say the change is needed to prevent a rise in throat and other cancers among men.

Since September 2008, girls in the UK aged 12-13 years have been offered the HPV vaccination. HPV stands for human papilloma virus – a group of viruses that are spread through direct contact and infect the moist mucous membranes in the body, such as the nose, mouth, throat, rectum, vagina and cervix.

While successful in combating cancers in women, there is a growing pressure across the world to extend HPV programmes to boys. In Australia a programme has already been introduced and some experts believe it should be introduced in the UK. They argue that it would combat the rise in HPV-related head and neck cancers in men and, in particular, would protect gay men who derive no direct protection from the vaccination programme in women.

Although throat cancer is rare, under the current HPV vaccination programme girls are receiving additional protection against viruses that may cause it, while boys are not. This has caused debate, with experts from the Throat Cancer Foundation quoted in the media as saying that this issue is a “ticking time bomb” and is discriminatory against boys

Professor Simon Rogers, consultant maxillofacial surgeon at the University Hospital Aintree, is quoted by the BBC as saying that if current trends continue, cases of throat cancer will exceed cervical cancer cases by the year 2020.

The Throat Cancer Foundation wishes to extend the vaccination programme to boys to give a “gender neutral vaccination”. But, on the strength of the current evidence, the Department of Health currently has no plans to extend the vaccination programme.

Human papilloma viruses (HPV) are viruses that infect the moist mucous membranes in the body – such as the nose, mouth, throat, rectum, vagina and cervix. The viruses can be spread through direct skin-to-skin contact or sexual contact. 

There are more than 100 different strains (types) of HPV. These are numbered and can cause different types of disease or infection. HPV viruses are very common, and many people will be infected with one form or another at some point in their lives. Many people will be infected with an HPV virus that causes no symptoms or only mild symptoms – such as veruccas or warts on the hands and feet. These usually go away without treatment.

But some strains of HPV are more dangerous and can cause changes to cells, which can trigger the onset of cancer.

The cancers that different HPV viruses have been associated with include:

• cervical cancer 
• vaginal cancer
• vulval cancer
• anal cancer
• penile cancer
• certain cancers of the head and neck, including cancer of the mouth, oesophagus (food pipe) and larynx vocal cords or voice box)

Using a condom during any sexual contact is a good way to protect against HPV strains that infect the genitals. However, as condoms do not cover the whole genital area they cannot give complete protection.

The NHS HPV vaccination programme was introduced in September 2008. The original vaccine (Cervarix) gave protection against HPV strains 16 and 18, which are known to account for around 70% of cervical cancer cases. Since 2012 the vaccine Gardasil has been used. This protects against four HPV strains – 16 and 18 and also 6 and 11, which cause around 90% of genital warts.

Currently, girls aged 12-13 are routinely vaccinated. There was also an initial ‘catch-up’ campaign to cover girls under 18. The vaccinations are given as part of a three-dose schedule over 12 months, and involve giving a viral protein in a structure called a virus-like particle (VLP). Live HPV virus is not given, and no serious side effects have been associated with the vaccination programme.

The primary aim of the NHS HPV vaccination programme is to protect against cervical cancer, by providing immunity against the two HPV strains that cause most cases of cervical cancer. However, while strains 6 and 11, which are included in the vaccination, are the main cause of genital warts in both girls and boys, only girls are currently receiving this protection.

All four strains in the vaccine have been associated with cancers in men. In particular, strains 6 and 11 may cause warty growths to develop on the larynx (vocal cords) or in the oesophagus (food pipe). These growths can undergo cancerous changes and cause throat cancer.

The NHS does not provide HPV vaccination to males. Boys and men who want the vaccination have to pay for it privately. 

The Throat Cancer Foundation gives statistics that 35% of throat cancers are caused by HPV, with oesophageal cancer most associated with the virus. The charity quotes Professor Margaret Stanley, Director of Research at the University of Cambridge, who says that: “If recent incidence trends continue, the annual number of HPV-positive oropharyngeal cancers is expected to surpass the annual number of cervical cancers by the year 2020”.

An editorial published in the journal Nature last year points out that HPV causes 5% of all human cancers. It also highlights the fact that genital warts (caused by HPV) are the commonest sexually transmitted viral disease. While genital warts are not especially serious they can be upsetting as well as both expensive and time-consuming to treat. Despite this, only females are currently given protection against HPV through the NHS vaccination programme.

Professor Stanley provides figures of the “sex-neutral burden” of HPV-related warts and cancers. HPV types 6, 11, 16 and 18 have been related to the following conditions:

• head and neck cancers – 12,700 new cases in males in Europe every year, and 2,530 in females
• genital warts – 325,700 new cases in males in Europe every year, and 289,000 in females
• anal cancer – 1,700 new cases in males in Europe every year, and 2,930 in females
• cervical cancer – 23,250 new cases in females in Europe every year
• vulva and vaginal cancer – 3,850 new cases in females in Europe every year
• penile cancer – 1,090 new cases in males in Europe every year

Professor Stanley references, among other sources, an article published last year in the journal BioMed Central (see the further reading section). This article was written by Hartwig et al. of Sanofi Pasteur MSD, which is a company specialising in vaccines. (This potential conflict of interest was stated clearly in the article.)

The study aimed to look into the burden of HPV-related disease in men in Europe, including genital warts and cancers of the anus, penis and head and neck cancers. The researchers used Eurostat population data, cancer incidence rates published by the International Agency for Research on Cancer, and prevalence estimates of HPV viruses 6, 11, 16 and 18.

This modelling study reported that, every year, 72,694 new cancer cases develop in European men at HPV-related sites on the body (for example, the penis, anus, head and neck). They estimate that almost a quarter of these cancers (17,403) could be directly attributable to HPV, with 15,497 of them specifically caused by HPV 16 or 18.

In addition, it was estimated that between 286,682 and 325,722 new cases of genital warts attributable to HPV 6 or 11 occur annually in European men. The study concluded that around 30% of all new cases of cancer caused by HPV 16 or 18 in Europe occur in men.

Meanwhile, almost all non-cancerous HPV-related conditions in men (for example genital warts) are caused by HPV strains 6 and 11. The authors say that the HPV vaccine could potentially prevent these conditions.

In her editorial, Professor Stanley continues that HPV vaccine trials have shown that the vaccine can protect against HPV infection and related anal and genital disease in men, but what is less clear is whether vaccination of men is cost effective.

She discusses that, in theory, the ‘herd immunity’ of all vaccinated females would give protection to men who only have sex with women, but that would not protect men who have sex with men.

She also points out that limiting the distribution of the vaccine to men who have sex with men to save money would be problematic since, to be most effective, the vaccine should be given during the early teenage years, when sexual preferences may not be established.

Overall, Professor Stanley concludes that: “it is not ethical, fair or socially responsible to have a public-health policy that forces men to rely on herd immunity, which won’t be reached for decades”. She says: “Let’s start vaccinating men now.”

The Throat Cancer Foundation wishes to extend the vaccination programme to include boys, making it a so-called “gender neutral vaccination”. The Foundation disputes current policy, which relies on “herd immunity” – meaning that if 80% of the female population is vaccinated then this will give protection to men. Echoing Professor Stanley’s standpoint they raise issues about the discriminatory nature of this policy, including against men who have sex with men (MSM). This group, which has the highest burden of anal cancers, is unprotected by the current HPV vaccination programme.

The United States, Canada and Australia currently recommend vaccination for both girls and boys, and they believe that we should follow suit. 

A Department of Health spokesperson, quoted in the BBC News coverage of the story, said: “There are currently no plans to extend HPV vaccination to males, based on an assessment of available scientific evidence.

"Vaccination of boys was not recommended by the Joint Committee on Vaccination and Immunisation because once 80% coverage among girls has been achieved, there is little benefit in vaccinating boys to prevent cervical cancer in girls.

"Eighty per cent coverage for the full course of three doses of the vaccine was achieved in the first year of the HPV vaccination programme in 2008-9, and has since exceeded that level."

Yes. The Gardasil vaccine is available from most private vaccination clinics. The cost of the complete course of the vaccine (three doses) can range from around £300 to £400 depending on the provider.  

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links To The Headlines

'Universal HPV vaccination' call. BBC News, February 1 2013

Call for boy cancer vaccine. ITV News, February 1 2013

A “vegetarian diet reduces heart disease risk by up to a third”, Channel 4 News reports. The news, which has been reliably covered by much of the media, is based on an impressive and wide-ranging UK study on nutrition.

Researchers recruited nearly 45,000 people in England and Scotland. They followed up with them for an average of 11 years, using hospital records and death certificates to determine how many of them developed coronary heart disease during that time (e.g. suffering angina, coronary heart disease or having a heart attack).

Compared to people who ate meat and fish at the start of the study, the vegetarians were less likely to be diagnosed with, or die from, coronary heart disease over the following years.

This association held even when the researchers adjusted for factors that are known to be linked to heart disease, including weight, sex, age and smoking status.

This study suggests that there are significant heart benefits to a vegetarian diet, which, the researchers argue, are probably due to the fact that eating a vegetarian diet involves eating less cholesterol than a typical meat eater. Also a vegetarian diet may lead to healthier blood pressure.

Although there may be other health and lifestyle factors not studied that could also be associated with both being vegetarian and having a lower risk of heart disease, overall this was a large, long-term study that suggests there are heart health benefits to a vegetarian diet.

But it is uncertain whether everyone would enjoy the same reduction in risk in the unlikely event that everyone in the UK turned ‘veggie’ overnight.

Where did the story come from?

The study was carried out by researchers from the University of Oxford and was funded by Cancer Research UK and the UK Medical Research Council.

The study was published in the peer-reviewed American Journal of Clinical Nutrition.

The media covered this research appropriately, with the Mirror rolling out the best pun of the day with its “Heart beet” headline.

This was a prospective cohort study that examined the association of a vegetarian diet with the risk of developing coronary heart disease (e.g. angina or heart attack), which in this study the authors called by the alternative medical term of ischaemic heart disease (IHD). This is a general term to describe a number of conditions where the supply of blood the muscles of the heart becomes restricted.

The researchers say that while previous studies have looked at the link between vegetarianism and risk of dying from IHD, few prospective studies have looked at differences in both fatal and non-fatal IHD between vegetarians and meat eaters.

Ischaemic heart disease usually arises due to a thickening of the artery walls due to a build-up of fatty products, such as cholesterol, which restrict the flow of blood through the coronary arteries that supply the heart.

There are several factors that are known to increase one’s risk of IHD, some of which cannot be changed and these include age, sex and a family history of IHD. Other 'modifiable' risk factors for ischaemic heart disease are related to lifestyle, and thus are more easily altered, including smoking, high blood pressure and high cholesterol.

The study recruited individuals over the age of 20 years between 1993 and 1997. As the researchers were interested in the association between nutrition and health, they specifically recruited vegetarians and vegans, as well as the UK general population.

The participants completed a food-frequency questionnaire that asked them about what they ate over the previous year. Based on their responses, the researchers classified them as either non-vegetarian if they reported eating any meat or fish, or vegetarians if they reported eating no meat or fish (for the purpose of the study, no distinction was made between vegetarians and vegans).

This information was collected again five years into the study’s follow-up period.

At this time, data was also collected on the participants’ height and weight, smoking status, alcohol consumption, level of education, physical activity levels and socioeconomic status. Participants were also invited to have their blood pressure and cholesterol levels measured.

The researchers then examined hospital records, national audit records and death certificates to determine if the participants were treated for (non-fatal) or died of (fatal) IHD during the follow-up period. They used this information, along with the data on IHD risk factors collected at the beginning of the study, to compare the risk of developing or dying from IHD between vegetarians and non-vegetarians.

Overall, 44,561 participants were included in the study, 34% of whom were vegetarians at the beginning of the research, and 76% of whom were women. Over an average of 11.6 years follow-up, there were 1,235 cases of IHD (1,066 of these were hospital admissions, and 169 were deaths). 

Overall, vegetarians tended to be younger than non-vegetarians, and were less likely to report receiving long-term medical treatment. Five years into the follow-up period approximately 85% of the vegetarian group reported that they were still vegetarians.

The researchers found that vegetarians had a 32% lower risk of developing IHD during the follow-up period compared to non-vegetarians (hazard ratio [HR] 0.68, 95% confidence interval [CI] 0.58 to 0.81).

In absolute terms, the probability of being hospitalised for, or dying of, IHD between the ages of 50 and 70 was 4.6% among vegetarians and 6.8% among non-vegetarians.

This reduced risk was seen among both continuous vegetarians and among those who were no longer vegetarians at five years’ follow-up.

When the researchers adjusted for BMI, the effect on IHD was lessened slightly to a 28% reduction among vegetarians compared to non-vegetarians (HR 0.72, 95% CI 0.61 to 0.85). The relationship also remained significant after adjusting for other risk factors associated with IHD such as smoking, alcohol, physical activity (or lack of it) and markers of socioeconomic status.

The researchers concluded that vegetarians had a 32% lower risk of IHD than non-vegetarians, and that this is likely due to “reduced levels of well-established risk factors for IHD, such as non-HDL cholesterol concentrations and systolic blood pressure”.

This large and impressive prospective cohort study suggests that a vegetarian diet may benefit your heart, reducing the risk of IHD.

However, there are important limitations to the study that should be considered before assuming the results apply broadly to the whole of the UK.

First, this study specifically and actively recruited vegetarians and vegans. In addition to GP practice-based recruitment, the researchers “aimed to recruit health-conscious people living throughout the UK”. People who take the effort to get involved in research involving diet and health tend to be more health conscious than the population at large (this is what is known as selection bias). As such, it is a non-representative sample, and the absolute figures of IHD cases among the 50-70 year olds in this study (6.8% in non-vegetarians and 4.6% in vegetarians) may not reflect the absolute risk in the general population.

Additionally, while all participants were invited to have their blood cholesterol levels measured at the beginning of the study, less than half did so.

The researchers suggest that much of the difference in IHD risk between the groups is associated with non-HDL (‘bad’) cholesterol levels and blood pressure. But due to the lack of available blood cholesterol data for all participants, further research using a more complete data set would be needed to confirm this interpretation.

Despite these limitations, this was a well-conducted, large long-term study that suggests there are heart healthy benefits to a vegetarian diet.

Analysis by NHS Choices. Follow Behind the Headlines on twitter.

Links To The Headlines

Going vegetarian can reduce your risk of hospital treatment or death from heart disease by a third. Daily Mail, January 30 2013

Vegetarians 'cut heart risk by 32%'. BBC News, January 30 2013

Heart beet: Veggie diet cuts chance of fatal heart disease by a third. Daily Mirror, January 30 2013

Vegetarians a third less likely to develop heart disease. The Daily Telegraph, January 30 2013

Vegetarian diet reduces heart disease risk by up to a third. Channel 4 News, January 30 2013

Links To Science

Crowe FL, Appleby PN, Travis RC, Key TJ. Risk of hospitalization or death from ischemic heart disease among British vegetarians and nonvegetarians: results from the EPIC-Oxford cohort study. The American Journal of Clinical Nutrition. Published online January 30 2013