Research news in brief

Benefits of healthy diet greater for those at high genetic risk of obesity

US research published in the BMJ has shown that the benefits of sticking to a healthy diet to prevent long term weight gain are greater in people at high genetic risk for obesity than in those with lower risk. The researchers analysed data from two large studies of US health professionals – 8828 women in the Nurses’ Health Study and 5218 men from the Health Professionals Follow-up Study from 1986 to 2006. Genetic risk score was calculated on the basis of 77 gene variants known to influence body mass index. Changes in body mass index and weight were calculated every 4 years. Changes in dietary patterns were also assessed every 4 years with three diet quality scores: the Alternate Healthy Eating Index 2010 (AHEI-2010), Dietary Approach to Stop Hypertension (DASH), and Alternate Mediterranean Diet (AMED). These diets are all rich in fruit and vegetables, nuts and whole grains, and low in salt, sugary drinks, alcohol and red and processed meats. After 20 years’ follow-up, the researchers found that improving adherence to the AHEI-2010 and DASH was associated with decreases in body mass index and body weight, and that the effect was more prominent in people at high genetic risk for obesity than those with low genetic risk. In addition, they noted that “the genetic risk of weight gain is attenuated by improving adherence to these healthy dietary patterns”. No clear interaction pattern was found for AMED. The authors pointed out that this was an observational study, so no firm conclusions could be drawn about cause and effect. Nevertheless, they said that their findings “highlight the importance of improving adherence to a healthy diet in the prevention of weight gain, particularly in people genetically predisposed to obesity”.

Concerns raised over animal trials

An investigation published by the BMJ has raised concerns about the poor quality, lack of regulation, and misrepresentation of animal studies for drug development. Led by the BMJ’s associate editor, Dr Deborah Cohen, the investigation and linked expert commentaries highlighted the “pick and mix” approach to animal research, and raised wider questions about lack of oversight and transparency, unaccountable regulatory decision making, and lack of clarity about what data are required when deciding to move from animal (preclinical) studies to human (clinical) trials. The investigation focused on MVA85A, a vaccine developed by researchers at Oxford University to boost the effectiveness of the BCG vaccine and provide extra protection against tuberculosis, which kills more than one million people each year. MVA85A was reported to have been shown to be effective in animal studies, but failed to show benefit when tested in a large clinical trial in South African infants in 2009.  An independent systematic review in 2015 concluded that the results of the animal studies had been overstated. It appears that a study in monkeys reported while the clinical trial was in the late stages of preparation should have raised doubts about the effectiveness of MVA85A. Although the monkey study was too small to draw firm conclusions, the results sparked concern in academic circles. But several months after the monkey study ended, the results were not included in information submitted to regulators for approval and funding of human trials of MVA85A. Jonathan Kimmelman, Associate Professor in the Biomedical Ethics Unit at McGill University in Canada, says that this is not an isolated case. “It’s widely recognised that animal studies intended to support drug development are often riddled with flaws in design and reporting. But it sometimes feels as if regulators and ethics committees missed the memo. Unfortunately, there are other cases where new treatments were put into human testing on animal evidence that was foreseeably flawed, incomplete, or even negative,” he said.

Genetic risk could guide prostate screening

A new score for predicting a man’s genetic risk of developing aggressive prostate cancer could help guide decisions about who to screen and when, according to research published in the BMJ. The researchers used data from an international study collaboration (the PRACTICAL consortium) to develop and test a genetic tool for predicting age of onset of aggressive prostate cancer and to guide decisions about who to screen and at what age. They analysed more than 200 000 gene variants (single nucleotide polymorphisms, or SNPs) in 31 747 men of European ancestry with and without prostate cancer, and identified 54 SNPs associated with increased risk of prostate cancer. These polymorphisms were incorporated into a survival analysis to estimate their effects on age at diagnosis of aggressive prostate cancer in the form of a hazard score. To validate the final model, it was applied to data from an independent clinical trial of 6411 men. The hazard score was a highly significant predictor of age at diagnosis of aggressive cancer; men in the top 2% of the score had an almost three-fold greater risk for aggressive prostate cancer than men with average risk. The researchers commented that the score is representative of a man’s fixed genetic risk, so “it can be calculated once, long before onset of prostate cancer, and substantially inform the decision of whether he should undergo screening”. They acknowledged some study limitations, and could not rule out the possibility that other, unmeasured factors may have influenced their results. Nevertheless, they said these results “add to existing data as further evidence that genetic features can predict risk of prostate cancer”.

Housework not so healthy for elderly, tired women

German research, published in BMC Public Health, has found that elderly women spent an average of almost 5 hours a day doing housework, compared with about 3 hours a day for elderly men. The study also found that while those who did more housework felt healthier, women who combined long hours of housework with too much or too little sleep reported poorer health. The researchers surveyed 15 333 men and 20 907 women over 65 about their daily activities, sleep, and overall health. The study found notable differences between the type of housework men and women did. Across all countries included in this study, men spent less time cleaning, cooking and shopping than women (88.7 minutes a day, compared with 217.9 minutes a day). However, women were found to spend less time on gardening and maintenance tasks than men (38.5 minutes a day, compared with 68.8 minutes a day). The researchers found that elderly women in Italy and Germany spent the most time on housework (about 5 hours a day), while those in the US spent the least time (4 hours a day). In contrast, elderly men in Italy spent the least amount of time on housework (2.7 hours a day) and German men the most time (4.2 hours a day).

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