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A groundbreaking study from the USC Leonard Davis School of Gerontology indicates that prolonged exposure to extreme heat may accelerate biological aging in older adults. The findings raise concerns about the long-term health impacts of climate change and increasing global temperatures.
The study, published in Science Advances, analyzed data from over 3,600 participants aged 56 and older across the U.S. Researchers discovered that individuals living in hotter climates showed more significant biological aging compared to those in cooler regions.
Understanding Biological Aging
Unlike chronological age, which is determined by birth date, biological age reflects how well the body functions at the molecular and cellular levels. Having a biological age higher than one’s chronological age is linked to an increased risk of disease and mortality.
While heat exposure has long been associated with negative health effects such as dehydration, heat exhaustion, and even death, its link to biological aging has remained unclear until now.
Measuring the Effects of Heat
The study, led by Jennifer Ailshire, professor of gerontology and sociology at USC, and co-author Eunyoung Choi, examined blood samples collected over six years from Health and Retirement Study (HRS) participants. Researchers analyzed epigenetic changes—modifications in DNA methylation patterns that influence gene expression—to estimate biological aging.
Using mathematical tools called epigenetic clocks, the researchers compared participants’ biological age changes with local temperature trends from 2010 to 2016. The study categorized heat index values into three levels:
- Caution (80°F–90°F)
- Extreme Caution (90°F–103°F)
- Danger (103°F–124°F)
Days falling into the latter two categories were classified as “heat days.”
Results showed a strong correlation between living in areas with frequent heat days and accelerated biological aging. Notably, participants residing in places where extreme heat occurs for half the year—such as Phoenix, Arizona—experienced up to 14 months of additional biological aging compared to those living in regions with fewer than ten heat days per year.
Implications for Public Health and Urban Planning
Older adults are particularly vulnerable to heat stress due to their decreased ability to regulate body temperature. Ailshire emphasized the importance of considering humidity levels alongside temperature, as high humidity can further impair the body’s cooling mechanisms.
“If you’re in a high-humidity place, you don’t get as much of a cooling effect from sweating,” Ailshire explained. “You have to consider both temperature and humidity to assess the real risk.”
Researchers plan to explore other factors that might make individuals more susceptible to heat-related biological aging and how these changes translate into clinical health outcomes.
The study’s findings highlight the need for policymakers, urban planners, and architects to incorporate heat mitigation strategies into infrastructure planning. Solutions could include planting more trees, increasing urban green spaces, and designing shaded bus stops and sidewalks to help protect vulnerable populations.
“As temperatures continue to rise and the population ages, we must be proactive in developing smarter mitigation strategies to safeguard public health,” Ailshire said.
Disclaimer: This article is based on scientific research and is for informational purposes only. It should not be considered medical advice. Individuals concerned about heat-related health risks should consult with healthcare professionals.
