Does your lifestyle play the biggest role in determining your risk of age-related conditions, or does the influence of your genes dominate? Thanks to the largest study of its kind, we now have our most comprehensive view yet of how these two factors influence the chance of developing 22 conditions, including dementia and heart disease.
Prior studies have linked a wide range of environmental factors to . But these have involved just a few thousand people and didn鈥檛 look at the risks of specific age-related conditions.
To fill this gap, at the University of Oxford and her colleagues analysed lifestyle and genetic data, collected for the UK Biobank, from more than 400,000 people aged between 40 and 73 at the time.
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鈥淚t鈥檚 the largest study looking at the exposome, those environmental factors, and their role in age-related diseases,鈥� says van Duijn.
Each participant provided blood samples 鈥� a source of genetic data 鈥� and answered surveys about their age, sex and lifestyle habits, such as those related to physical activity, smoking and how long they slept each night. The team combined this with data taken from the health records of each participant over the subsequent decade or so, revealing whether they had 22 age-related conditions. These included dementia, coronary heart disease and breast cancer.
The researchers found that all of these factors could only explain around half the risk of most of the conditions. Outside of this 鈥渆xplainable鈥� risk, the rest is probably somewhat down to random events, such as genetic mutations that lead to cancer, and to interactions between people鈥檚 genetics and their lifestyle, says at Columbia University in New York. For example, exercise can alter the chemical tags on DNA and cause cells to behave differently, despite having the same genetic sequence.
Nevertheless, the team found that lifestyle had a bigger influence than genetics on the risk of 12 of the conditions, while genetics carried more weight for the other 10.
For instance, lifestyle had double the effect on participants鈥� risk of developing coronary heart disease than their genetics. It also explained more than 30 per cent of the overall explainable lung and liver cancer risk, while genetics had very little impact.
In contrast, genetics accounted for 35 per cent of participants鈥� explainable dementia risk, while just 10 per cent of the risk was down to lifestyle. Similarly, 86 per cent of participants鈥� explainable breast cancer risk was due to genetics, while just 9 per cent seemed to be caused by lifestyle.
鈥淭hat鈥檚 not surprising 鈥� depending on the disease, we do know that some have more or less of a genetic component,鈥� says Cohen. 聽Still, the results provide one of the most comprehensive views on how lifestyle and genetics affect our health, he says.
The team also found that smoking and being less wealthy were among the factors that most strongly raised the risk of the age-related conditions. Education and physical activity were among those that most strongly reduced this risk.
鈥淭his information can lead us to better insights into how we can prevent age-related conditions and how we can target interventions to the groups that may be at greater risk of disease due to environmental exposures,鈥� says at King鈥檚 College London.
But the study doesn鈥檛 prove these links are causal, says Siow. It also involved mainly white, wealthy people who are healthier than the general population, so further research in more ethnically diverse, poorer and less healthy populations is needed, he says.
Nature Medicine
