Why This Matters to Us
As longevity enthusiasts, we understand that keeping the body and mind youthful is essential to improving lifespan and quality of life. The link between extreme heat exposure and accelerated biological aging raises new concerns for those of us focused on improving health as we age. This study highlights the critical need for adapting environments to minimise the effects of rising global temperatures. Addressing climate-related challenges like heat exposure supports our broader goal to promote healthier and longer lives worldwide.
The Detail
A groundbreaking study published in Science Advances explored how daily exposure to high heat levels impacts biological aging. Researchers Eun Young Choi and Jennifer Ailshire from the University of Southern California investigated this link using data from 3,686 older adults (aged 56 and above) over a six-year period (2010–2016).
By relying on three DNA methylation-based biological aging measures—PCPhenoAge, PCGrimAge, and DunedinPACE—the study quantified the impact of heat on cellular aging. These ageing clocks assess biological age by examining changes in DNA methylation, a process where chemical markers influence gene expression without altering genetic code. Essentially, the study determined how far biological aging outpaces chronological age under different heat conditions.
The findings showed that older adults living in regions with extreme heat experienced significantly accelerated aging. For instance, individuals living in areas like Phoenix, Arizona—where temperatures exceed 90°F (32.2°C) for nearly half of the year—aged 14 months more biologically than peers living in cooler climates. This conclusion was remarkably consistent across all three aging clocks.
The researchers categorised exposure to heat into short-term (e.g., seven days or 30 days) and long-term (e.g., one year and six years) timeframes. While short-term heat exposure showed some link to aging (notably using the PCPhenoAge clock), dramatic biological aging effects came from long-term exposure. For example:
- Those who experienced one-year extreme caution-level heat (temperatures above 90°F) aged 2.48 years biologically according to PCPhenoAge.
- Over a six-year period, the DunedinPACE clock showed biological aging speeds increasing even with smaller differences in annual heat exposure.
How Heat Plays a Role
Older adults face compounding risks from heat exposure due to the natural decline in their bodies’ cooling systems. Physiological functions that regulate body temperature, like sweating and skin blood flow, become less effective with age. Furthermore, extreme heat may increase stress and anxiety, which have their own negative impacts on health and aging. Poor sleep caused by heat-related restlessness could also accelerate the process, as the body relies on sleep to repair and maintain itself.
Interestingly, while prolonged exposure to cold temperatures has been linked to potential longevity benefits in some animal studies, the opposite appears to occur in hot conditions for older adults, accelerating biological decline instead.
The Effects of Climate Change
This study becomes increasingly alarming when viewed through the lens of climate change. By 2050, more than 100 million Americans are predicted to live in areas where high heat events occur more frequently. This means a significant portion of the older population could face prolonged exposure to dangerous temperatures, putting their longevity and well-being at risk. Existing cooler regions, such as those near Canada or mountainous areas like the Rockies, may provide some relief from heat—for now. However, projections suggest that climate change may eventually warm even these areas.
What We Can Do to Reduce the Risks
While it's unlikely most older adults can simply relocate to cooler climates, there are actionable solutions that could slow heat-induced aging. Creating shady green spaces and better urban infrastructure in southern cities like Phoenix could significantly reduce heat-related aging risks. Shaded areas, as well as access to affordable air conditioning, would help older adults regulate their body temperatures more effectively during long, hot seasons.
Additionally, managing other factors such as stress and anxiety caused by heat may offer further protection against accelerated aging. Improving sleep hygiene during summer months and maintaining physical activity in temperature-controlled spaces are two small steps that could make a noticeable difference.
Wrapping It Up
This research provides powerful insights into how our environment—particularly extreme heat—shapes the aging process. As the number of hot days we experience annually continues to rise, it’s clear more efforts are needed to adapt urban areas and protect vulnerable populations. For older adults, addressing heat exposure is not just about comfort—it’s about safeguarding longevity and ensuring a higher quality of life.