Oxford Study: Environmental Exposures Help Explain Age-Related Death Risk Tenfold More Than Genetics

Highlights

• In their assessment of almost 500,000 UK residents, the Oxford researchers uncovered that for 22 age-related diseases, having certain genetic profiles conferring disease risk helped explain less than 2% of deaths.
• This low contribution of genetics to mortality was dwarfed by environmental factors, which helped explain about 17% of deaths from age-related diseases.
• Some of the age-related diseases assessed, such as dementia and prostate cancer, were more attributable to genetics, while heart, liver, and lung diseases were associated more with environmental factors.

The dilemma of whether genetics or environmental factors play a greater role in aging and early death has remained unclear. The observation that global life expectancy has more than doubled over the last few centuries while genetics have remained more or less stable has led some to believe environmental factors contribute more. All the same, no studies to date have sufficiently assessed the contributions of environmental and genetic factors to aging until a recent publication in Nature Aging by van Duijn and colleagues at the University of Oxford in the UK.

In the publication, van Duijn and colleagues uncover that less than 2% of early deaths from age-related diseases were associated with certain genetic profiles that confer disease risks. Contrastingly, environmental factors that the researchers refer to as the exposome—a host of environmental exposures we encounter during life—helped explain about 17% of early deaths from age-related diseases. Further analyses of aging based on proteins in the blood suggested that particular environmental factors like maternal smoking around the time of birth and lower socioeconomic status were associated with a faster pace of aging. Moreover, certain diseases were more attributable to genetic risk than environmental exposure, such as colon and prostate cancers, while heart, liver, and lung diseases were linked more to environmental factors. Altogether, data from the study suggest that environment-focused aging intervention strategies may work best to reduce the risk of early death and counteract many age-related diseases.

Previous research attempting to uncover the contribution of genetic and environmental factors to aging has estimated that genetics can explain about 25% of the effects of aging. The same research attributed about 75% of aging to environmental factors. Contrastingly, van Duijn and colleagues’ study suggests that environmental factors contribute about 10 times more than genetics to premature mortality (deaths before age 75) from age-related diseases. Furthermore, the Oxford University researchers’ study suggests that chronological age and sex account for about half of the risk of premature death—an aspect not fully addressed in previous research on genetics and environment.

“Overall, our results indicate that environment-focused interventions are possibly the most strategic starting point for ameliorating premature mortality and most age-related morbidity, although future causal modeling will be needed to study specific exposures of interest,” said van Duijn and colleagues in their publication.

Modifying Environmental Exposures May Counteract Aging

In an attempt to measure the degree to which environmental factors contribute to premature mortality, van Duijn and colleagues measured whether 164 environmental exposures were associated with the risk of premature death. These environmental exposures ranged from salt intake to living with a partner. After excluding certain factors like exposures related to an existing disease, the team identified 85 environmental exposures associated with a risk of premature death. The researchers then carried out an analysis of aging based on proteins in the blood to identify which of the 85 exposures were also associated with a more rapid pace of aging.

Through this sequence of analysis, van Duijn and colleagues ultimately identified 25 environmental exposures, including things like whether the participants’ mothers smoked around their birth and household income. These 25 identified environmental exposures were associated with a higher risk of premature death and accelerated aging. Interestingly, alcohol intake and dietary choices were not included in these identified environmental exposures, which, according to the researchers, was likely due to difficulties in investigating these exposures through the questionnaires provided for the study.

Importantly, among the 25 environmental exposures identified in the study that were associated with age-related diseases and accelerated aging, 23 can be modified. In other words, people can change their habits to minimize the adverse effects of these environmental exposures.

In their study, van Duijn and colleagues also assessed the association between certain genetic predispositions for age-related diseases and mortality. In doing so, they found that these genetic predispositions helped explain only about 2% of premature deaths. The environmental exposures, on the other hand, explained about 17% of the risk for premature death. This finding suggests that the contribution of environmental exposures to premature death is almost 10 times that of genetic factors.

“We provide some of the first evidence from a well-powered study to map all of the exposures that influence ageing on the biological level,” said M. Austin Argentieri, a contributing author, in a press release. “We further show that these exposures are plausibly linked to the entire ageing process across adulthood, as they are associated with key biological mechanisms of ageing, future risk of age-related diseases and mortality.”

Altering Environmental Exposures to Live Longer

The results from the study support the previous research suggesting that, in most cases, our genes are not the primary determinant of how long we live. In other words, our genes may give us a certain degree of predisposition to one or more age-related diseases, but environmental exposures like physical activity or our socioeconomic status may play a larger role in whether such diseases progress.

Ultimately, with the researchers’ assessment that 23 out of 25 of the key environmental factors influencing aging can be modified, perhaps the most effective way to fight aging is to identify which environmental risk factors you can alter. In that sense, going through the 25 factors listed in the graph below and modifying certain ones like whether you smoke and how physically active you are may extend the duration of your life in a disease-free state.