Extreme heat can accelerate aging in older adults, suggests research

A new USC Leonard Davis School of Gerontology study suggests that greater exposure to extreme heat can speed up biological aging in older adults, so that new concerns are expressed about how climate change and heat waves can influence long-term health and aging at a moleculary level.

The research is published in the diary Science is progressing.

People in neighborhoods that experience more days of high heat show on average greater biological aging than residents of cooler regions, said Jennifer Ailshire, senior author of the study and professor of gerontology and sociology at the USC Leonard Davis School.

Biological age is a measure of how well the body functions in the molecular, cellular and system levels, in contrast to a chronological age based on a person’s date of birth; Having a biological age higher than someone’s chronological age is associated with a higher risk of illness and mortality.

Although exposure to extreme heat itself has long been associated with negative health results, including an increased risk of death, the link of heat with biological aging is unclear.

Measuring epigenetic changes

Ailshire and her co-author Eunyoung Choi, USC Leonard Davis Ph.D. In Gerontology Alumna and Postdoctoral Scholar, investigated how the biological age changed in more than 3,600 health and pension study (HRS) participants aged 56 and older of the US.

Blood samples taken at different times during the six-year study period were analyzed for epigenetic changes, or changes in the way in which individual genes are “disabled” or “to” by a process called DNA methylation.

The researchers used mathematical tools called epigenetic clocks to analyze methylation patterns and to estimate biological ages at any time. They then compared the changes of the participants in the biological age with the history of the heat index of their location and the number of heat days reported by the National Weather Service from 2010 to 2016.

The National Weather Service Heat Index Chart categorizes heat index values ​​in three levels based on the potential risk of adverse health effects.

The “warning level” level includes heat -index values ​​ranging from 80 ° F to 90 ° F, the level “Extreme caution” includes values ​​between 90 ° F and 103 ° F, and the “Danger” level includes values ​​between 103 ° F and 124 ° F. Days. Days.

The analysis revealed a significant correlation between neighborhoods with more days of extreme heat and individuals who experience a greater increase in biological age, Choi said. This correlation continued to exist, even after control of socio -economic and other demographic differences, as well as lifestyle factors such as physical activity, alcohol consumption and smoking, she added.

“Participants who live in areas where heat days, such as extreme caution or higher levels (≥90 ° F), occur half -year, such as Phoenix, Arizona, experienced extra biological aging for up to 14 months compared to those in areas with less than 10 heat days a year,” she said.

“Even after checking for various factors, we found this association. Only because you live in an area with more heat days, you get older biologically faster.”

All three epigenetic clocks used in the study Pcphenoage, PCgrimage and Dunedinpace- have kept this association in analyzing epigenetic aging for a period of one to six years. Pcphenoage also showed the association after short (seven days) and medium-sized (30-60 days) time periods, indicating that heat-related epigenetic changes can occur relatively quickly, and some can accumulate over time.

Climate implications for communities

Older adults are particularly vulnerable to the effects of high heat, Ailshire said. She noted that the study of heat index used, instead of just air temperature, to take into account relative humidity when analyzing the results.

“It’s really about the combination of heat and humidity, especially for older adults, because older adults do not sweat in the same way. We are starting to lose our ability to have the skin -cooling effect that comes from the evaporation of sweat,” she explained.

“If you are in high humidity, you don’t get that cool effect that cooling effect. You have to look at the temperature of your region and your humidity to really understand what your risk could be.”

The following steps for the researchers will be to determine which other factors can make someone more vulnerable to heat -related biological aging and how it could connect with clinical results.

In the meantime, the research results can also encourage policymakers, architects and others to keep heat limitation and age -friendly characteristics in mind while updating the infrastructure of cities, from placing sidewalks and building bus stops with shadow in mind to plant more trees and increase the urban green space, Ailshire said.

“If everywhere gets warmer and the population gets older, and these people are vulnerable, then we really have to get much smarter about these mitigation strategies,” she said.