Highlights

  • Older adults living in areas of the US where heat levels reach 90℉ or greater at least half the year were predicted to age 14 months more.
  • Three assessments of biological age—an aging measurement based on cell and tissue function—agreed that higher numbers of elevated heat days drive accelerated aging.
  • Such findings showcase the need for urban interventions, such as shady areas, in southern US regions since older adults lose their physiological skin-cooling capabilities.

Published in Science Advances, Ailshire and Choi from the University of Southern California provide data suggesting that a higher number of days with elevated heat over six years accelerates biological aging in older adults. The researchers assessed this with three biological age tests that use DNA molecular tagging patterns (DNA methylation), all of which predicted accelerated aging associated with high-heat environments. This finding highlights the need for urban planning and development endeavors that incorporate shady areas and green spaces into cities to possibly alleviate heat-induced rapid aging for older individuals.

Extreme heat events, where temperatures reach 90℉ or greater, are expected to increase rapidly with climate change and affect more than 100 million Americans by 2050. Older adults will be especially susceptible to heat-related weather events since their bodies’ physiological cooling system functionally declines as they age.

Heat In Southern US Regions May Accelerate Aging 14 Months Over a Six-Year Period

In an attempt to unravel how high-heat weather affects aging, Ailshire and Choi analyzed 3,686 US adults aged 56 and above, measuring their exposure to elevated heat between 2010 and 2016. The researchers obtained their heat exposure-related data from the National Weather Service. The research duo then compared study participants’ heat exposure levels to DNA methylation-based biological aging tests to find whether people living in US regions with more days where heat reaches 90℉ and above age faster.

Interestingly, the methylation-based aging tests predicted that older adults living in hotter regions like Phoenix, Arizona aged 14 months more than those who experienced 10 or fewer days per year where temperatures reached 90℉. The researchers defined these warmer regions as places with high temperatures for nearly half of the year. This finding means that over the six years of analysis, older people living in these warm regions appeared to age an extra 14 months.

For analyses of shorter-term elevated heat exposure over seven days, 30 days, 60 days, and a year, one of the three aging clocks—PCPhenoAge—measured significantly accelerated aging. The other two aging clocks, PCGrimAge and DunedinPACE, only predicted accelerated aging over the longer six-year span of weather-related heat exposure. These findings suggest that, especially for longer-term heat exposure, older adults in warmer regions age at a faster pace than those who live in cooler climates.

“Even after controlling for several factors, we found this association. Just because you live in an area with more heat days, you’re aging faster biologically,” said Eun Young Choi, one of the study’s authors, in a press release.

Testing Whether Lifelong Exposure to a High-Heat Environment Accelerates Aging

Interestingly, some researchers believe colder temperatures may work to enhance longevity, and there is some evidence in lower-order organisms suggesting that this may be the case. Whether colder climates extend the lifespan of humans remains a matter of debate, but according to Ailshire and Choi’s data, a converse phenomenon may ensue. In this case, hot weather-related events, especially over prolonged periods, appear to accelerate aging.

This scenario may apply only to older individuals since their bodies’ physiological cooling mechanisms deteriorate over time. However, future research should examine the effects of growing up in a region of the US with elevated numbers of hot days yearly. Currently, no known data provides an answer to whether young people exposed to elevated temperatures over extended periods age faster.

Aside from the reduced function of the body’s cooling system with age, other contributing factors that may accelerate aging in a warmer environment could be stress and anxiety. In that sense, some research links heat-related weather events with stress and anxiety. Elevated stress and anxiety from heat could also impair sleep, making people restless during the night, which could contribute to aging.

Furthermore, for people concerned about the potential of high-heat environments to drive aging, moving to areas with fewer days with elevated heat may serve as a way to avoid premature aging. In that sense, it appears that virtually all of the states bordering Canada, as well as locations in the Rocky and Appalachian Mountains, may provide relief from prolonged periods of heat. This circumstance may change in the next 20 to 50 years, though, depending on how much global climate change influences heat’s impact on these regions.

For people who choose to remain living in areas associated with high heat, urban planning could help mitigate the environment’s effects on aging. As such, incorporating more shady green spaces in places like Phoenix, Arizona may help older people avoid the age-related consequences of long-term heat exposure. Moreover, heat’s potential impact on aging makes it crucial that older people have access to suitable air conditioning to try and prevent heat-related aging and shortened lifespan.