A new groundbreaking study conducted by the USC Leonard Davis School of Gerontology has revealed a concerning link between extreme heat exposure and accelerated biological aging in older adults. This significant research raises alarms about the implications of climate change and heat waves on long-term health, particularly at the molecular level. Researchers found that individuals residing in neighborhoods with higher occurrences of extreme heat days are subject to greater biological aging than those living in cooler areas. This investigation leads to a better understanding of how environmental factors can influence aging processes, shining a light on an often-overlooked aspect of gerontology.
The study is anchored by the insights of Jennifer Ailshire, the senior author, who serves as a professor of gerontology and sociology at USC. Her collaboration with postdoctoral scholar Eunyoung Choi reveals a clear differentiation between biological age and chronological age, where biological age offers a more nuanced perspective on an individual’s health by evaluating their physiological functions instead of simply counting the years since birth. This emphasis on biological age proves particularly poignant, as a greater biological age correlates with increased risk of diseases and higher mortality rates.
Utilizing health data from more than 3,600 participants aged 56 and older, Ailshire and Choi meticulously gathered blood samples across a span of three years. The research team analyzed these samples for epigenetic changes—variations in gene expression that regulate whether genes are activated or deactivated through a process known as DNA methylation. By employing sophisticated epigenetic aging clocks, the researchers quantified the biological ages of study participants, allowing for a robust analysis of the impacts of heat exposure on their aging trajectories.
As the study unfolded, participants’ biological ages were methodically compared against historical heat index data, which detailed the number of extreme heat days reported by the National Weather Service from 2010 to 2016. The heat index itself is a critical tool, as it integrates not just temperature but also relative humidity, offering a more comprehensive view of how heat affects individuals, especially older adults who are less capable of cooling themselves through sweating.
The correlations indicated a startling trend: those living in locales where extreme heat days are prevalent—such as Phoenix, Arizona—suffered significant biological aging, sometimes up to 14 months more than their counterparts in cooler regions with fewer than ten heat days annually. Even after accounting for various socioeconomic and lifestyle factors, the relationship remained profound, underscoring just how detrimental prolonged exposure to heat can be to biological health.
Three distinct epigenetic clocks used in the study—PCPhenoAge, PCGrimAge, and DunedinPACE—all consistently reinforced the findings, suggesting that heat may trigger epigenetic changes that could manifest swiftly, hinting at the potential for chronic repercussions over time. Particularly, PCPhenoAge exhibited notable changes even within short-term heat exposure periods, pointing to an urgent need for further inquiry into how these stressors accumulate and relate to long-term health outcomes.
The study also emphasizes the added vulnerability of older adults in high-heat environments, as their physiological response to humidity and temperature diverges sharply from younger populations. Ailshire’s findings highlight the compounded risks faced by older individuals, whose bodies are less adept at managing heat stress. The acknowledgement of humidity alongside temperature illustrates a more complex role that these elements play in a person’s health, leading to dire implications if urban environments fail to adapt.
As climate change continues to exacerbate heat waves, the researchers strongly advocate for urban planning that considers the health and safety of aging populations. Their insights urge policymakers and city planners to implement strategies designed to mitigate heat exposure, incorporating features such as shaded pavements and increased greenery within urban settings to provide refuge from harsh temperatures.
These revelations stress an imperative call to action for both individuals and communities to engage in proactive measures. The potential for climate change to influence biological aging necessitates that vulnerable individuals be educated about risks and encouraged to seek out cooler environments whenever possible. Moreover, as cities adapt to a heating climate, fostering a culture of awareness regarding the impacts of heat can empower residents to mitigate risks actively.
Future research endeavors aim to explore additional variables that may heighten individual susceptibility to heat-induced biological aging, looking to bridge the gap between environmental stressors and their clinical outcomes. As our understanding of these complex interactions deepens, the hope remains that emerging knowledge will inform better public health interventions and enhance the resilience of aging communities facing escalating climate challenges.
As the implications of this study reverberate across the fields of gerontology and public health, an everlasting pursuit of knowledge about the intersection of environmental conditions and health continues. The urgency of raising awareness about the impacts of heat exposure on biological aging is paramount, driving both scientific inquiry and human-centric urban design to protect some of the most vulnerable populations in our society.
The landmark study titled “Ambient Outdoor Heat and Accelerated Epigenetic Aging among Older Adults in the U.S.” was published in the journal Science Advances, highlighting the critical intersection of gerontology and climate science. As researchers gather more data and further refine their methodologies, the hope is to produce a clearer understanding of how to best shield aging populations from the relentless encroachment of heat-induced biological aging, laying forth a path toward healthier futures amid climatic challenges.
The collaboration between researchers at the USC Leonard Davis School of Gerontology signifies a pivotal moment where interdisciplinary studies may pave the way for innovation. This research widens the lens through which we consider public health, intertwining it with environmental realities that shape our physical well-being. The future trajectory of aging studies must incorporate these findings fully, shaping not only health policies but also urban landscapes which reflect a deeper understanding of human health in an era of climate change.
As the release date of this pivotal research approaches, anticipation builds around the potential for widespread impact—encouraging discussions, influencing policy changes, and, ultimately, fostering an improved quality of life for the aging population who remain susceptible to the ravages of extreme heat in a warming world.
Subject of Research: Aging, Heat Exposure, Environmental Health
Article Title: Ambient Outdoor Heat and Accelerated Epigenetic Aging among Older Adults in the U.S.
News Publication Date: February 26, 2025
Web References: http://dx.doi.org/10.1126/sciadv.adr0616
References: Available upon request.
Image Credits: USC/Eunyoung Choi
Keywords: Aging, Epigenetics, Climate Change, Biological Aging, Public Health, Heat Exposure, Urban Planning, Senior Health, Environmental Stressors, Gerontology, Heat Index, Humidity Effects.
Tags: aging and mortality ratesbiological aging in older adultsbiological vs chronological ageenvironmental factors and gerontologyextreme heat and aginghealth data analysis in agingheat waves and health risksimpact of climate change on healthimplications of heat exposure on older populationsJennifer Ailshire research studymolecular aging processesUSC Leonard Davis School of Gerontology
