Ageing and mortality shaped by environment more than genetics

Environmental factors could be more influential in health and premature death than our genes, according to a new study.

Publishing their findings in Nature Medicine, a research team from Oxford Population Health aimed to quantify the contributions of genetics and environmental factors (such as smoking, physical activity, and socioeconomic status) in ageing and mortality. Their findings suggest that the combination of many environmental factors throughout a lifetime, referred to scientifically as an exposome, could shape disease and mortality risk more so than genetics.

'Our exposome approach allowed us to quantify the relative contributions of the environment and genetics to ageing, providing the most comprehensive overview to date of the environmental and lifestyle factors driving ageing and premature death. These findings underscore the potential benefits of focusing interventions on our environments, socioeconomic contexts, and behaviours for the prevention of many age-related diseases and premature death,' said Dr Austin Argentieri, Oxford Population Health and research fellow at Massachusetts General Hospital, Boston.

In the largest study of its kind, using almost 500,000 participants from the UK Biobank, a biomedical database that tracks hundreds of thousands of people across the UK, the team identified 25 environmental factors that influence 22 major diseases. They monitored how rapidly participants were ageing using blood protein levels in a method dubbed the 'ageing clock', allowing them to associate environmental exposures that affect mortality with biological ageing.

While other studies have documented the impact of environmental factors on diseases, this study is the largest to look at an array of factors affecting premature death and ageing. Of the 25 environmental factors found, the study suggests smoking, socioeconomic status, living conditions, and physical activity had the most impact on mortality and biological ageing. For instance, the paper claims that maternal smoking around the time of birth could potentially affect mortality risk 80 years later.

Nevertheless, the paper concluded genetics more heavily influenced age-related diseases such as dementia and colorectal, breast and prostate cancers rather than the environment.

'Our research demonstrates the profound health impact of exposures that can be changed either by individuals or through policies to improve socioeconomic conditions, reduce smoking, or promote physical activity,' added Cornelia van Duijn, professor of epidemiology at Oxford Population Health.

However, the researchers do note the limitations of their findings. The UK Biobank cohort is healthier and more affluent than the general UK population and, therefore, not entirely representative. Additionally, the exposomes were measured at a one-time point and not across a lifetime and cannot make claims on what would happen should a participant stop smoking or change their diet.

'This is an exciting study. The fact that most of the risk factors identified are modifiable highlights an enormous opportunity for prevention... however, some caution is needed. This is an observational study, so further research is needed to confirm causal relationships, especially before any long-term policy changes are made,' countered Felicity Gavins, professor of pharmacology at Brunel University of London.