Heat Waves, Climate Change, and Implications for an Aging Population Free

The prevailing scientific consensus attributes the increase in intensity and frequency of heat waves to climate change (1,2). Meanwhile, cities, acting as “heat islands,” often reach higher temperatures than their surrounding areas (3). Due to this combination of climate change and urban-induced warming, what we currently deem as “extreme” heat could become the norm by mid-century (4). Further, climate change-related threats such as wildfires increase the risk of infrastructure failures, which, coinciding with hot weather, can result in drastic outcomes (eg, a city-wide blackout during hot weather) (5). In light of these alarming trends, this editorial summarizes the challenges facing the older adult population and proposes areas of research aimed at helping them adapt to the new climate reality.

The Socioeconomic Dimension of Vulnerability

Socioeconomic factors play a substantial role in determining exposure and vulnerability to heat. For example, urban density and vegetation cover influence ambient temperature and the associated health outcomes (6). As a result, lower socioeconomic populations are often at a higher risk as they tend to live in densely populated and less green areas (7). Further, socioeconomic challenges may limit access to cooling resources such as air conditioning (AC) (8). There also exists a disparity in indoor heat exposure attributable to the housing itself, as individuals from lower socioeconomic backgrounds often reside in homes that are more prone to overheating (9). Furthermore, extended heat waves increase the risk of AC equipment failure in individual households, disproportionately affecting those who lack resources for preventative maintenance, or repair of AC (10).

Aging and Vulnerability to Heat

It is well established that the capacity to maintain stable internal body temperature diminishes with age due to impaired thermoregulation, fluid regulation, and cardiovascular function (11). Conditions whose prevalence increase with age such as type 2 diabetes reduce the density of sweat glands and thus reduce the heat-regulatory role of perspiration. In addition, autonomic nervous system dysfunction, a critical component of the neural substrate of heat adaptation, is often altered in older adults due to underlying pathologies (eg, Parkinsonism) and/or iatrogenic effects (eg, medications). These biological factors significantly increase the susceptibility of older individuals to heat. Additionally, age-related decline in cognitive and motor functions can restrict older adults’ ability to regulate their thermal environment. Social factors also play a role as many older adults who live alone lack the essential support needed during extreme heat.

Adaptive Strategies and Barriers to Implementation

Different strategies have been proposed and tested, often at small and local scales, to increase resiliency to heat. At the individual level, health care providers and families can play a critical role in managing the impacts of hot weather on health and well-being of older adults by providing guidance and encouraging adaptive behavior. At the societal level, adaptive strategies may include implementation of heat risk warning systems, addressing financial barriers to using AC, providing access to public cooling centers, community awareness campaigns, and community surveillance for at-risk individuals. It is also possible to create a heat-resilient built environment by reconsidering our architectural designs, especially in subsidized housing, and creating a cooler urban environment through strategies such as reflective rooftops and increased vegetation cover.

Yet, despite the demonstrated success of these interventions, large-scale implementation remains elusive. A majority of our older adult population is thus vulnerable to the projected rise in temperatures. A myriad of factors—political, economic, psychological, and technological—converge, complicating the path to action. Among them, one persistent barrier is the limited knowledge regarding optimal and cost-effective deployment of these strategies. It is crucial to expand research on adaptive strategies, understanding their efficacy at different scales, and optimizing them for specific communities, because the effectiveness of solutions is often contingent on environmental, cultural, and socioeconomic contexts.

Call to Action

The United Nations has declared the current decade as the “Decade of Healthy Ageing.” We argue that given the current climate trajectory, promoting the health and well-being of older adults, which is the core principle behind this declaration, requires advocating for immediate policy changes that protect the older population from heat. Equally important is the need to address the knowledge gaps in areas of research that can offer insights and tangible solutions:

• Heat Vulnerability Assessment: We must develop and refine tools to assess heat vulnerability in older adults, taking into consideration biological, environmental, and socioeconomic factors. This will enable targeted research, more sensitive evaluation of interventions, and ultimately, better allocation of available resources.

• Cooling Innovations: We must explore affordable and easy-to-use cooling technologies specifically designed for older adults, and especially for those individuals with cognitive and/or mobility issues (eg, fabrics and clothing innovations, wearable technology).

• Behavioral Response to Heatwaves: We must better understand the behavioral patterns that older adults exhibit during heatwaves. For example, why might some choose not to use AC or visit cooling centers even when available? Is it due to cost, lack of knowledge, or some other factor?

• Mental Health and Heatwaves: Heatwaves decrease mental health, and increase impulsivity, suicide rate, and crime (12). It is important to investigate the neural basis of mental and brain health impact of weather fluctuations in general and heat exposure in particular to develop strategies to manage its potential consequences during and after heat waves.

• Health Implications of Prolonged Heat Exposure: It is imperative to investigate the effects of heat exposure on health outcomes beyond heat-related hospitalization. In addition to mental health, emerging evidence suggests that over time, high ambient temperatures likely have longer-term deleterious impacts on cognition, sleep (13), mobility, and falls. At the population level, factors that contribute to increased heat exposure (eg, urban density and less green space) and some of its consequences (eg, disrupted sleep, physical inactivity) have also been epidemiologically linked to increased risk of dementia (14). As such, we must establish how and why higher ambient temperatures contribute to the complex “exposome” of Alzheimer’s disease and related dementias.

• Heat-Resilient Housing: AC cannot be our only solution to this problem, as associated greenhouse gas emissions contribute to climate change. Research into building designs and materials that can offer optimal thermal comfort without relying on AC at all times is crucial.

• Urban Cooling Strategies: The spatially averaged effect of individual urban cooling strategies such as reflective or green roofs on ambient temperature is typically small, which may lead to resistance to implementing them. However, case studies have demonstrated their potential impact on health outcomes (15). More importantly, even a small cooling effect at the urban scale reduces the burden on our energy infrastructure and health care systems during a heat wave, making our cities more resilient. We therefore encourage studying the cost-effectiveness of these solutions in different climates and at different scales in order to optimize their implementation.

• Public Health Messaging and Education: Public health campaigns must reach older adults in different communities. We thus believe it is important to identify the best channels of communication, as well as messaging that addresses language and cultural barriers in order to optimally resonate at the individual community level.

We implore our diverse readership, whether you are researchers, policymakers, geriatricians, or citizens, to contribute to and support ongoing research into these areas. This journal particularly welcomes submissions that propose innovative solutions to help older adults adapt to the new climate reality.

Funding

None.

Conflict of Interest

None.

References