New Study Finds That Heat Accelerates Aging Process

Although many people across the country crave warmer weather this time of year, a new study published in “Science Advances” might make them reconsider. The study found that extreme heat — like that which many of us experienced last summer — accelerates the aging process. To be exact, prolonged exposure to extreme temperatures can modify how our genes behave, speeding up aging at the molecular level and potentially affecting our long-term health.

A Look at Epigenetic Aging

When most people think about getting older, they think in terms of chronological age — as in how many birthdays someone has had. But biologically, if you were to “count the rings” of a person, so to speak, one person who’s 70 won’t be the same as another who’s 70, because numerous genetic and environmental factors affect how our bodies age. So, scientists started using epigenetic aging as the benchmark for predicting age-related health conditions.

Epigenetic, or biological, age is typically determined through methylation — very simply put, a process that cells use to lock genes in the “on” or “off” position. Methylation doesn’t change the genes themselves, NPR explains in its article on this new study, but modifies the way those genes work. Studies in humans and other animals  have shown that these patterns change over time and can be used as a sort of molecular clock that can measure biological age.

A person’s epigenetic age is affected in a number of ways. This biological aging can accelerate due to poor diet, lack of exercise, emotional or physical stress, as well as exposure to environmental harms like air pollution, and in this case, heat.

The New Study, Explained

Researchers looked at blood samples from more than 3,600 older adults across the U.S. and assessed those subjects’ epigenetic ages. They then cross-referenced those results with how much heat those people experienced over a few days, a few months, one year and six years prior to the sample collection using climate and weather models. 

Fig. 1 Ambient outdoor heat measures across time windows
Image Credit: Science Advances

The researchers also assessed the other variables that often affect one’s epigenetic age, such as their financial status, education, physical activity levels and whether they smoked. 

Even factoring those in, the outcome of the study was clear that people who experienced more heat over the long term aged faster biologically than those living in cooler places. Eun Young Choi, a gerontologist at the University of Southern California’s Leonard Davis School of Gerontology, and the study’s lead researcher, told NPR that the impact is “similar to the effect of smoking and drinking.”

Why This Matters

With greater understanding of the mechanisms for why and how long-term exposure to extreme heat affects people the way it does, scientists hope to be able to prevent the damage caused, or even potentially reverse it. This will have increasing importance in the upcoming years, as escalating climate change is likely to continue to wreak havoc with global temperatures.