Heatwaves and Aging: New Study Links Extreme Heat to Faster Biological Aging
Heatwaves have long been linked to increased hospitalizations and deaths, but new research suggests they may also accelerate biological aging in older adults. As climate change continues to intensify heatwave frequency and duration, this raises concerns about its long-term impact on human health.

Unlike chronological age, which is based on birthdate, biological age reflects the body's functional state at a molecular and cellular level. A higher biological age than chronological age is associated with increased risk of disease and disability due to reduced cellular efficiency.

Heat Stress and DNA Changes
Previous animal studies indicate that extreme heat can trigger lasting chemical modifications in DNA through a process called methylation, affecting various cell functions, including immune response and heart health. However, limited research has examined similar effects in humans.

To explore this, Dr. Eunyoung Choi and Prof. Jennifer Ailshire from the University of Southern California analyzed blood samples from over 3,600 adults aged 56 and older between 2010 and 2016. They assessed gene activity changes caused by methylation and estimated biological aging. These findings were then compared with the number of extreme heat days each participant experienced.

Heat and Accelerated Aging
Published in Science Advances, the study found a strong correlation between repeated exposure to heat index values of 32°C (90°F) or higher and accelerated biological aging. This was observed even after accounting for socioeconomic factors, lifestyle habits, and demographic differences.

For example, individuals living in high-heat areas such as Phoenix, Arizona, where extreme heat days occur for half the year, showed up to 14 months of additional biological aging compared to those in regions with fewer than 10 extreme heat days annually.

Older adults are particularly vulnerable due to diminished sweating ability, which reduces the body's natural cooling effect. High humidity further exacerbates this risk by limiting sweat evaporation.

"If everywhere is getting warmer, the population is aging, and these individuals are more vulnerable, we need to be much smarter about mitigation strategies," said Prof. Ailshire.

Source: https://www.gavi.org/vaccineswork/do-heatwaves-make-us-age-faster