A Critical Gap in Addressing Mental Health in Heat-Health Action Plans Worldwide

Abstract

Purpose of Review

Extreme heat is associated with mental health conditions such as suicide, anxiety, and substance use disorders. However, the integration of mental health in heat-health planning remains limited and no comprehensive assessment of its inclusion exists to date. This review aims to (1) identify and categorize mental health-related content in heat-health action plans globally; and (2) analyze the gaps in included interventions related to extreme heat and mental health.

Recent Findings

A review of 83 heat-health action plans from 24 countries revealed that while 75.9% of plans mentioned mental health, only 31.3% acknowledged its specific impacts and 21.7% included targeted interventions. These plans covered approximately 2.2 billion people, representing about 26% of the 2024 global population. Most interventions were directed at the societal level, with limited attention to individual or community-level support. Individuals with mental illness were commonly grouped with other vulnerable populations without tailored support. Low-income countries were not represented, while 44 plans (53.0%) came from high- and upper-middle-income countries. Among lower-middle-income countries, most plans originated from India (35; 89.7%).

Summary

Despite recognition of the impacts of extreme heat on mental health, heat-health action plans lack comprehensive strategies to address these risks. The findings highlight a broader challenge within climate adaptation policies, where the recognition of mental health risks is often not matched by necessary resources, planning, and interventions. Given the critical gaps in mental health inclusion, greater efforts and resources are needed to integrate targeted mental health strategies into heat-health plans and policies.

Introduction

In 2023–2024, extreme heat (hotter than 90% of temperatures observed in their local area over the 1991–2020 period) was estimated to impact 6.3 billion people worldwide, representing around 78% of the world’s population [1]. While research on extreme heat-related health impacts has largely focused on physical health outcomes—including cardiovascular strain [2], heat stroke [3], and kidney damage [4]—there is a large burden of mental health risks associated with extreme heat [5]. Globally, approximately one in eight people live with a mental disorder and mental disorders are the leading cause of years lived with disability (YLDs), contributing to one in every six YLDs worldwide [6]. Here, we define ‘mental health’ to include both mental disorders (e.g., depressive and anxiety disorders) and broader aspects of psychological wellbeing (e.g., resilience and emotional regulation).

Mental health impacts of extreme heat exposure – both immediate and with lagged effects – include increased risk of suicide [7–9], symptoms of schizophrenia [2], anxiety disorders [2], depressive disorders [5], substance use disorders [2,11], increased negative emotions and reduced positive emotions [12], lower sleep quality [13,14], increased fatigue [12], as well as increased risk of mental health-related hospitalization [7,15,16] and mortality [2,17] among people with pre-existing mental health problems. Certain communities are particularly vulnerable to the mental health impacts of extreme heat, including low-income populations [18], individuals experiencing homelessness [19], individuals living in inadequately cooled institutions (including prison populations or those in medical centers) [20,21], older adults [22], children [23,24], and individuals with pre-existing mental health conditions [25]. Increasing frequency of extreme heat events driven by climate change not only exacerbates the vulnerability of individuals with pre-existing mental health conditions, but also increases the risk of developing new mental health conditions [25,26]. This includes long term changes to neurodevelopment for unborn and very young children exposed to extreme temperatures that appear to place them at higher risk of mental health disorders [27,28].

Adaptation to extreme heat is a key component of resilience to climate change. The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) urged governments to adopt comprehensive strategies to protect mental wellbeing during extreme climate events, including heatwaves [29]. The World Health Organization (WHO)’s Mental Health Action Plan (2013–2030) highlighted the need for mental health promotion and prevention across all sectors and settings [30].

Heat-health action plans have been developed to guide local implementation of strategies for adapting to the health risks of extreme heat [31,32]. Formal heat-health action plans were first developed at scale following the European heatwave of 2003, which killed over 35,000 people [33]. The importance of these measures has been championed by initiatives such as the World Meteorological Organization’s Early Warning Systems for All [34] and the United Nation (UN)’s Call to Action on Heat [35]. In 2008, the WHO Regional Office for Europe published the first comprehensive guide for developing heat-health action plans at national, regional, and local levels [36], with updates in 2011 [37] and another expected in 2025 [38]. These guidelines outline eight core elements for an effective heat-health action plan, including care for vulnerable populations and real-time surveillance, monitoring, and evaluation [36].

A key metric for comprehensive climate change adaptation is explicit incorporation of mental health impacts and interventions. Previous studies have evaluated the implementation of heat-health action plans [32,39–41], but no studies have focused specifically on whether or how they address mental health considerations. Here, we assess the extent to which mental health considerations are integrated into heat-health action plans worldwide. The objectives of this study are: (1) to identify and categorize mental health-related content in heat-health action plans globally, and (2) to analyze the gaps in interventions related to extreme heat and mental health and establish future priorities. By reviewing a comprehensive set of heat-health action plans worldwide, this analysis provides both a critical evaluation of the current integration of mental health considerations into heat-health planning, and outlines recommendations for more effective future inclusion of relevant mental health interventions.

Methods

Study Design

Our aim was to use qualitative content analysis to assess the extent to which mental health considerations are integrated into heat-health action plans worldwide, with a focus on assessing coverage of mental health impacts and risk factors and categorizing interventions across different levels of the socioecological model [42].

Heat-Health Action Plans

Here, as in previous work by Czerniewska et al. [43], the Global Heat Health Information Network (GHHIN) and WHO compiled heat-health action plans, hereafter referred to as ‘plans’, on a global scale. The previous analysis by Czerniewska et al. focused on considerations and interventions related to maternal and child health within these plans.

Search Strategy

Between April 4 and July 31, 2024, the GHHIN and WHO conducted a comprehensive search to locate plans at both national and subnational levels. This involved issuing a public request for plans via the GHHIN email list and directly contacting WHO maternal, newborn, and child health regional managers, members of a WHO working group on extreme heat and maternal, newborn, and child health, and the High Horizons project network. Additionally, the GHHIN and WHO research team explored publicly accessible databases related to climate-health planning documents, including GHHIN, Climate ADAPT, Reliefweb, and various United Nations resources such as National Adaptation Plan databases and Health and Climate Change Country Profiles. They assessed references lists from recent reviews of heat-health action plans, and contacted authors of these reviews for additional information [32,39,40,44–46].

To further broaden the search, the GHHIN and WHO research team conducted Google searches using terms related to heat, climate adaptation, and planning actions, along with each country name for all 195 member states and non-member observer states of the United Nations. They also translated the search terms into local languages using Google Translate. Further details on the search strategy can be found in Czerniewska et al. [43].

Eligibility

The GHHIN and WHO research team defined plans as a national or subnational government-authored plan or strategy that considered the health risks of heat and presented a comprehensive set of prospective planned or recommended actions to mitigate the effect of heat on human health, or to increase resilience to heat in the population. They included plans if they covered the health impacts of heat across all demographics and sectors, rather than focusing solely on specific environments like workplaces. They translated plans that were not originally in English using Google Translate. Both reviews considered the most recent iterations of identified plans, published since 2004—marking the early development of heat-health action plans following the 2003 European heatwave —up until July 31, 2024, in any language supported by Google Translate. Additional details on inclusion and exclusion criteria can be found in Czerniewska et al.[43].

Data Extraction

For each plan, we extracted data on the geographic and administrative level—referring to the level of governance responsible for the heat-health action plan (i.e., national, regional, or subregional)—as well as the title and publication year, institutional authors, and language. We implemented a focused data extraction process targeting references to mental health within these plans. This involved searching all plans for words related to mental health and wellbeing such as mental, psych*, resilience, wellbeing, counsel*, cope, emot* and terms for specific mental health disorders and symptoms (Supplementary Table 1). Experts in climate and mental health and psychiatric epidemiology provided feedback on the search terms.

Defining Mental Health

We defined ‘mental health’ broadly to include both mental disorders (e.g., depressive disorders, anxiety disorders, post-traumatic stress disorder) and general psychological wellbeing (e.g., resilience, coping, and emotional health). This definition was intended to capture a wide range of references to mental health across the reviewed plans. However, broader wellbeing-related concepts were not discussed in the plans and were therefore not included in the final analysis. We did not include neurodegenerative or neurodevelopmental disorders, as these conditions, while potentially increasing the risk of mental health conditions, primarily involve structural or developmental differences in brain function rather than psychological or emotional health.

Analysis Framework

We conducted a content analysis of all identified plans. We coded text segments that were identified via the search terms into key themes (initially using those that we determined a priori) including mental health-related outcomes, heat exposure risk factors related to mental health, mechanisms linking extreme heat and mental health, and mental health interventions and recommendations. We classified mental health-related outcomes into two categories: those based on psychiatric classifications, broadly following the fifth edition off the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) [48], and other mental health-related outcomes not classified within the DSM. Since the plans did not explicitly reference diagnosed mental health conditions but rather broader psychological symptoms, such as anxiety or depression, we categorized these mentions within corresponding DSM-5-TR classifications, such as anxiety disorders and depressive disorders, for consistency. We distinguished between ‘feeling anxious’, suggesting non-clinical distress, and ‘anxiety’, which could imply a clinical diagnosis, based on the context of the text segment. We iteratively expanded the code system with sub-codes based on themes that emerged upon reviewing the extracted text segments. These included specific types of mental health-related outcomes (e.g., specific DSM-classified disorders), risk factors, and interventions. We conducted data extraction and coding using MAXQDA (version 24.5.1).

We used the coded segments to perform descriptive statistics, assessing the extent to which the plans mentioned and addressed different aspects of the heat - mental health nexus. This included quantifying and qualitatively describing references to mental health generally, specific mental health-related outcomes, heat exposure risk factors related to mental health, and relevant interventions. We analyzed the inclusion of mental health in the plans across countries, by WHO region [49], World Bank income levels [50], and administrative levels.

We employed the socioecological model to guide our analysis of mental health interventions [51]. The socioecological model is a widely recognized framework in public health that emphasizes the complex interplay between individual, interpersonal, organizational, community, and policy-level factors in shaping health outcomes. We used the simplified version of the model focusing on individual, relationship, community, and societal level factors, which has been used by the U.S. Centers for Disease Control and Prevention and other public health agencies for health promotion [42]. We classified interventions at each level based on their primary mechanisms of action. The individual level included interventions that targeted personal behavior or treatment. The relationship level encompassed interventions focused on interpersonal dynamics, including family support or peer support networks. The community level referred to interventions aimed at engaging local communities, such as community education programs or community-based mental health services. The societal level included interventions focused on broader systemic changes, such as greenspace and infrastructure strategies, national mental health strategies, and large-scale education campaigns. This multi-level perspective is useful for understanding how interventions can operate across different levels of society, ensuring that our findings are relevant for mental health promotion and protection, including through relevant policy and intervention development and implementation. We identified gaps in the consideration of mental health within the plans, focusing specifically on potential intervention opportunities related to extreme heat and mental health.

Results

We identified 83 plans, published during 2009 – 2024, that met the inclusion criteria (Table 1; Supplementary Table 2). These plans cover approximately 2.2 billion people or 26% of the 2024 global population. Each plan is hereafter cited with parentheses at the end of each reference in the format of ‘(location, year of publication)’, e.g., ‘(Bangladesh, 2024)’. The 83 plans spanned 24 countries, with the South-East Asian region contributing the most plans (37 plans came from 3 countries; 44.6% of all plans), with most South-East Asian plans coming from India (35; 94.6% of South-East Asian plans). The European region was the region where the largest number of countries had a plan (26 plans from 14 countries; 31.3% of all plans) (Fig. 1). The plans were distributed between low-middle income economies (39; 47.0% of all plans) and high-income economies (41; 49.4% of all plans), with three plans (3.6% of all plans) from upper-middle income economies. No plans were identified from countries classified as low-income economies. The plans included 18 national-level plans (21.7% of all plans), 32 regional-level plans (38.6% of all plans), and 33 sub-regional level plans (39.8% of all plans), such as districts or cities. The majority of plans (60; 72.3% of all plans) were published between 2020 and 2024, with fewer plans published during 2015–2019 (16; 19.3% of all plans) and 2009 – 2014 (7; 8.4% of all plans).

Table 1.

Heat-health action plans included in analysis (n = 83)

	Number of plans (% of all included plans)	Number of plans that included mental health information (row %)
Countries by WHO region (N = National plan, R = Regional plan, S = Subregional plan)
African Region	1 (1.2)	1 (100.0)
South Africa (1N)	1 (1.2)	1 (100.0)
Americas Region	11 (13.3)	8 (72.7)
Argentina (1S)	1 (1.2)	0 (0.0)
Canada (1R, 4S)	5 (6.0)	3 (60.0)
USA (3R, 2S)	5 (6.0)	5 (100.0)
Eastern Mediterranean Region	2 (2.4)	1 (50.0)
Pakistan (1R, 1S)	2 (2.4)	1 (50.0)
European Region	26 (31.3)	21 (80.8)
Austria (1N, 3R, 1S)	5 (6.0)	4 (80.0)
Belgium (1R)	1 (1.2)	1 (100.0)
France (1N)	1 (1.2)	1 (100.0)
Germany (1N)	1 (1.2)	0 (0.0)
Italy (1N)	1 (1.2)	0 (0.0)
Lithuania (1S)	1 (1.2)	1 (100.0)
Luxembourg (1N)	1 (1.2)	0 (0.0)
Netherlands (2N)	2 (2.4)	1 (50.0)
North Macedonia (1N)	1 (1.2)	1 (100.0)
Portugal (1N)	1 (1.2)	1 (100.0)
Spain (1N, 3R, 1S)	5 (6.0)	5 (100.0)
Sweden (1N, 2S)	3 (3.6)	3 (100.0)
Switzerland (1N, 1R)	2 (2.4)	2 (100.0)
UK (1N)	1 (1.2)	1 (100.0)
South-East Asian Region	37 (44.6)	29 (78.4)
Bangladesh (1N)	1 (1.2)	1 (100.0)
India (1N, 14R, 20S)	35 (42.2)	28 (33.7)
Nepal (1N)	1 (1.2)	0 (0.0)
Western Pacific Region	6 (7.2)	5 (83.3)
Australia (5R);	5 (6.0)	4 (80.0)
New Zealand (1N)	1 (1.2)	1 (100.0)
Country Income Level by World Bank Classification
Low	0 (0.0)	0 (0.0)
Lower-middle	39 (47.0)	28 (71.8)
Upper-middle	3 (3.6)	2 (66.7)
High	41 (49.4)	33 (80.5)
Administrative Level
National	18 (21.7)	12 (66.7)
Regional	32 (38.6)	28 (87.5)
Subregional	33 (39.8)	23 (69.7)

Fig 1.

Identified heat-health action plans by country

A total of 63 plans (75.9%) included some mention of mental health, including mention of mental health-related outcomes, risk factors, mechanisms, or interventions (Table 2). The Western Pacific Region had the highest proportion of mental health inclusion (5 of 6; 83.3%), followed by the European Region (21 of 26; 80.8%) (Table 1; Fig. 2). At the national level, the highest proportion of plans mentioning mental health was found for high-income countries (33 of 41; 80.5%). Across administrative levels, regional plans had the highest proportion mentioning mental health (28 of 32; 87.5%) (Table 1).

Table 2.

Mental health information in heat-health action plans s (n = 83)

	Number of Plans	Percentage of Plans (%)
Any mention of mental health (i.e., outcomes, risk factors, mechanisms, or interventions)	63	75.9
Any mention of mental health-related outcomes of extreme heat	26	31.3
Mental health-related outcomes of extreme heat (mental disorders broadly classified within the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR))
Any mention of classified mental health conditions	11	13.3
Anxiety Disorders	9	10.8
Depressive Disorders	4	4.8
Substance Use Disorders	3	3.6
Bipolar Disorders	1	1.2
Trauma- and stressor-related Disorders	1	1.2
Psychosis	1	1.2
Other mental health-related outcomes of extreme heat (excluding classified mental disorders)
Any mention of mental health-related outcomes (excluding classified mental health conditions)	22	26.5
General impacts on mental health	8	9.6
General impacts on wellbeing	7	8.4
Suicide	5	6.0
Sleep deprivation	5	6.0
Anxious	4	4.8
Irritability	4	4.8
Social isolation	3	3.6
Psychiatric hospitalizations	2	2.4
Mood change	2	2.4
Stress	2	2.4
Restlessness	1	1.2
Distress	1	1.2
Mortality among those with mental illness	1	1.2
Mental health-related risk factors for heat-related illness
Any mention of risk factors	53	63.9
Pre-existing mental illness (broadly defined)	48	57.8
Medications	28	33.7
Substance use	34	41.0
Social isolation	16	19.3
Mental health-related interventions
Any mention of interventions	18	21.7
Individual-Level Interventions	7	8.4
Relationship-Level Interventions	5	6.0
Community-Level Interventions	3	3.6
Societal-Level Interventions	10	12.0

Fig. 2.

Heat-health action plans by region and inclusion of mental health

Mental Health Outcomes

A total of 26 plans (31.3%) addressed the mental health-related outcomes associated with extreme heat (Table 2). Of these, 11 plans (13.3%) explicitly referenced mental disorders, broadly based on classification by the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR). The most frequent disorders mentioned were anxiety disorders (9; 10.8%) and depressive disorders (4; 4.8%). These conditions encompassed both new onset cases and the exacerbation of pre-existing mental illness during periods of extreme heat, though this distinction was not always explicitly made in the documents. For example, one plan explained that:

“many diseases, including neuropsychiatric disorders (e.g., psychosis, suicides, homicides, anxiety, and depression) are ‘heat sensitive’, meaning that they are either exacerbated or triggered by exposure to heat”

(Bangladesh, 2024).

Mental health-related outcomes not based on psychiatric classification were included in 22 plans (26.5%). The most commonly cited mental health-related outcomes included generally stating that heat exposure adversely impacts ‘mental health’ (8; 9.6%) and ‘wellbeing’ (7; 8.4%), for example highlighting that:

“Extreme heat can exacerbate a range of health risks from increased transmission of food, vector and waterborne disease, mental health manifestations, and drive increasing health inequities”

(England, UK, 2024–2025).

Other mental health-related outcomes mentioned were suicide (5; 6.0%), sleep deprivation (5; 6.0%), and feelings of non-clinical anxiety (4; 4.8%). In particular, plans referencing increased suicide risks in higher temperatures often cited prior studies that have found a positive and significant association between extreme heat and suicide. For example, one plan cited a systematic review by Thompson et al. [7] which found that a majority of included studies on suicide and temperature found a positive and significant association between increasing temperatures and suicide frequency (England, UK, 2024–2025).

Sleep deprivation was described as a consequence of high nighttime temperatures, particularly for those in crowded housing, that could exacerbate mental health issues such as psychological distress and anxiety. Feelings of anxiety (non-clinical) were often reported alongside physical symptoms such as dizziness, weakness, and fatigue due to heat exposure. In several plans, these symptoms were identified as warning signs that should prompt individuals to move to a cooler place and monitor their body temperature.

Risk Factors

A total of 53 plans (63.9%) mentioned risk factors or vulnerabilities for poor health outcomes with heat exposure that were related to mental health. Pre-existing mental illness (48; 57.8%) was the most frequently noted risk factor, describing general vulnerability to heat stress and heat exhaustion due to pre-existing mental illness. For example, one plan stated that:

“Vulnerability to heat stress and heat exhaustion in extreme heat conditions is more likely when there is a diagnosis of mental illness. As such, a lower activation threshold [for activating the action plan] is attributed to people registered to mental health services”

(South Australia, Australia, 2023).

The plans often included people with mental illness in a list of vulnerable groups along with adults 65 years and older, children under 5 years old, pregnant individuals or nursing mothers, and people with other pre-existing medical conditions. Additionally, 28 plans (33.7%) linked heat vulnerability specifically to medications used to treat mental illness. These included antidepressants, antipsychotics, anticholinergics, tranquilizers, neuroleptics, and serotonin agonists. Substance use (34; 41.0%) and social isolation (16; 19.3%) were other commonly cited risk factors for heat exposure that are relevant to mental health and often altered in people with mental health conditions. Recent and regular alcohol consumption was often included on a list of risk factors to look for when considering heat illness. Other drug use, including use of amphetamines, and general substance use disorders were also noted as risk factors for heat illness. Many plans also described people who were socially isolated, with few social contacts, as being at higher risk for heat exposure, particularly among older adults. As stated in one plan:

“Social, cultural, and linguistic isolation are all risk factors for heat illness because they limit access to information, resources, and social and emotional support systems”

(Boston, USA, 2022).

Another plan explained that individuals with mental illness are often socially isolated and may have limited contact with the medical system, making it difficult for them to seek support from a healthcare professional. They stated that:

“Others cannot bear the heat at all and increasingly isolate themselves when temperatures are high. Moreover, only a small percentage of people affected by mental diseases have contacts with the medical system. This lack of contact makes it more difficult to reach out to them and support them”

(Austria, Vienna 2022).

Mechanisms

Several plans (10; 12.0%) described mechanisms, referring to the physiological and social pathways through which heat exposure may influence mental health-related outcomes. Social isolation was mentioned not only as a risk factor for heat exposure but also a consequence of heat exposure, which could in turn negatively impact mental health. For example, one plan discussed how:

“Extreme heat events may cause people to isolate themselves in their homes and limit interpersonal interactions…Social isolation and extreme heat exposure can collectively worsen health risks such as depression, anxiety, and heart and respiratory dysfunction”

(Metro Boston, USA, 2022).

Medications such as psychotropic medications were cited as increasing the risk of complications from heat exposure by disrupting the body’s thermoregulation and reducing sweat production, as discussed in several plans. For example:

“SSRI preparations in combination with diuretics (thiazide or furosemide) increase risk of electrolyte disturbances (hyponatremia)”

(Kommunen Municipality, Sweden, 2023; Kalmar Municipality, Sweden, 2020).

Intoxication from alcohol or substance use were attributed to increased complications from heat exposure due to:

“Reduced bodily sensations so that dehydration, overheating or heatstroke is recognized less quickly”

(Austria, Vienna, 2022).

One plan described that people with pre-existing mental illness “may take slower action to improve their own situation” during extreme heat events, meaning that they may not take necessary protective action (Austria, Vienna 2022). Mental and physical disabilities may also make it harder to perceive or respond to the body’s warning signals during heat events (Kommunen Municipality, Sweden, 2023).

Interventions

Discussion of appropriate mental health interventions to mitigate the mental health risks associated with extreme heat exposure and provide appropriate support to affected individuals was relatively limited, with fewer than a quarter of plans (18; 21.7%) addressing any form of intervention (Table 2; Fig. 3; Supplementary Table 3). The most frequently discussed interventions were at the societal level (10; 12.0%), followed by individual-level interventions (7; 8.4%). Fewer interventions were mentioned at the relationship (5; 6.0%) and community (3; 3.6%) levels.

Fig. 3.

Mental health interventions categorized by levels of the socioecological model.

Several plans proposed structural and population-level interventions to reduce the impact of extreme heat on mental health. These included a national communication campaign aimed at preventing drug consumption and promoting responsible alcohol use during heatwaves (Portugal, 2022), and a proposal to establish reliable funding streams for community resilience hubs (Metro Boston, USA, 2022). There were six plans that mentioned increasing urban green spaces, cool roofs, or urban forests (Metro Boston, USA, 2022; Western Sydney, Australia; 2018; England, UK, 2024–2025; Port Moody, Canada, 2020; South Africa, 2020; Ahmedabad, India, 2019), aimed at cooling urban areas and improving physical and mental wellbeing. Other proposed societal-level interventions included educating healthcare workers on how to support individuals with mental illness during heat events and providing guidance on identifying and treating heat-related illnesses among patients with mental illness (England, UK, 2024–2025). Two plans proposed hospital preparedness plans for heatwave-related illness that ensured special accommodations for people with mental illness, such as ‘cool spaces or rooms’ for those with severe mental illness (South Africa, 2020; Thane City, India, 2024).

Community-level interventions focused on raising awareness and building local capacity to support vulnerable populations during extreme heat events. For example, education and awareness campaigns aimed at informing the community about the dangers of extreme heat and enhancing social cohesion and resilience were suggested (Western Sydney, Australia, 2018). Other recommendations included incorporating shelters for unhoused individuals in heat response planning and establishing shelters that can be rapidly mobilized to protect unhoused individuals in situations of medical, psychological, or social distress during heatwaves (France, 2017; Metro Boston, USA, 2022). A Community Climate Corps Program was proposed to engage frontline community residents in leading outreach, mutual aid, and advocacy activities related to enhancing community resilience in the face of extreme heat and other climate-health risks (Metro Boston, USA, 2022).

Relationship-level interventions focused on enhancing social networks and interpersonal support for individuals during heat events. For example, two plans recommended that caregivers, friends, and neighbors have regular contact with people with mental illness during heatwaves (Victoria, Australia, 2009; New Hampshire, USA, 2014). Other plans proposed that healthcare providers, educators, and caregivers work together to screen individuals at higher risk of heat-related illness and connect them to prevention resources (Metro Boston, USA, 2022; Andalusia, Spain, 2022). A neighborhood assistance program was proposed that would support people with mental illness and other vulnerable groups during heatwaves (Austria, Vienna, 2022).

Individual-level interventions were focused on providing direct support to people with mental illness during extreme heat events. These included telephone-based wellness checks for individuals considered at high risk (Victoria, Australia, 2017; Phoenix, USA, 2024) and the establishment of a hotline for information and counseling during heatwaves (North Macedonia, 2011; Switzerland, 2021). One plan recommended that mental health units intensify monitoring for patients with severe mental illness during heatwaves and offer advice on heat management (Andalusia, Spain, 2022). Other individual-level interventions included counseling at urban health centers about how to stay safe during high heat periods (Jodhpur, India, 2023) and conducting heat vulnerability assessments for individuals accessing mental health services, with additional monitoring during extreme heat events (South Australia, Australia, 2023).

Discussion

Summary

Our exhaustive global review of 83 heat-health action plans revealed a recognition of mental health within the context of extreme heat events, with most plans (75.9%) mentioning mental health in some capacity. However, approximately 1 in 5 plans still did not include any reference to mental health. Our finding reflects the growing acknowledgement of mental health as a critical component of overall health to be addressed and protected through climate adaptation, while also indicating that there is still room for improvement to ensure that mental health receives parity of esteem with physical health in the context of climate and health discussion. Importantly, apart from India, we found a disproportionately low number of plans from low- and middle-income countries. This gap suggests that heat-health planning may still be emerging in countries where the burden of heat and mental health problems is likely to be significant but under-addressed [52]. Most plans provided glancing references to mental health without providing adequate detail on the mental health impacts and outcomes, relevant risk and protective factors, pathways of impact, or proposed interventions.

Range of mental health-related outcomes

The range of mental health outcomes identified in the plans focused on both exacerbation of pre-existing mental health conditions and the emergence of new symptoms triggered by extreme heat. Specifically, anxiety disorders and depressive disorders were the most frequently referenced DSM-classified conditions linked to extreme heat exposure. In addition to DSM-classified conditions, our review found a range of mental health and wellbeing-related outcomes noted in plans, including suicide and sleep deprivation. The inclusion of these mental health and wellbeing outcomes aligns with previous research highlighting the mental health impacts of extreme heat, with evidence that extreme heat exposure both exacerbates existing mental health conditions and may contribute to the emergence of new mental health conditions, especially in vulnerable populations [2,26,53,54]. The links between extreme heat and suicide listed in the plans are consistent with peer reviewed studies, including studies indicating a link between extreme heat and increased suicide rates [7,8,10,55] and those highlighting that the psychological toll of heat-induced stressors can worsen social cohesion and contribute to heightened mental health risks [56–58].

Gaps in mental health outcomes, risk factors, and mechanisms of impact

Despite the mention of mental health in most plans, there were notable gaps and high variance in how mental health outcomes were identified and described. Most plans did not differentiate between the exacerbation of pre-existing conditions and the onset of new mental health symptoms triggered by heat. This distinction is important since the prevention and interventions required may vary considerably [59,60].

Our review revealed that many plans overlooked important mechanisms linking heat and mental health-related outcomes, such as the effects of heat on displacement and migration [26,61–64], food and water insecurity [65–67,26], climate-related economic losses [68,69,26], and sleep deprivation [14,70]. These mechanisms are particularly relevant for vulnerable populations who may face multiple stressors concurrently, further compounding mental health risks during heatwaves [71,72,26].

Vulnerable groups were generally not distinguished throughout the plans at a high enough precision for appropriate action. While some plans acknowledged the vulnerability of people with pre-existing mental illness, these plans often grouped them with other high-risk populations, such as older adults or children, without addressing the unique challenges faced by people with mental health conditions during extreme heat events. For instance, only one plan highlighted that people with pre-existing mental health conditions are at higher risk of dying during a heatwave [73].

Gaps in interventions

While mental health was acknowledged in many plans, only around a fifth of the plans proposed any form of intervention specifically targeted to protect people from poor mental health and wellbeing-related impacts during heatwaves. The socioecological model provided a valuable framework for understanding the various levels at which interventions can be implemented [42]. The interventions proposed in the plans were mostly situated at the societal level, focusing on broad public health measures such as communication campaigns, the integration of mental health support into public health systems, and infrastructure adaptations such as increasing green spaces or establishing “cool roofs.” While these interventions are valuable, they may overlook the role of community-level and relationship-level interventions, which are critical for addressing the social determinants of mental health, such as social isolation and lack of community support [74,75].

Some interventions were generally targeted at ‘vulnerable groups’, with only brief mention of individuals with mental illness. There was a noticeable gap between acknowledging mental health as a concern and implementing specific interventions to address it. This gap reflects a broader challenge within climate adaptation policies, where the recognition of mental health risks is often not matched by the necessary investment in resources, planning, and interventions. For example, according to WHO data, while 37% of national adaptation policies include a reference to mental health, only 5% include any reference to actions to address mental health and psychosocial needs [76].

Recommendations for Policy and Practice

At a minimum, future heat-health action plans should explicitly recognize the mental health impacts of extreme heat and identify people living with mental illness as a distinct vulnerable population. One of the primary gaps identified in this review was the lack of specific, actionable interventions for individuals with pre-existing mental health conditions. Our analysis highlights that many plans mention mental illness as a risk factor but do not propose targeted strategies for this population. While some risk factors, such as social isolation or the use of medications affecting thermoregulation, are also experienced by other vulnerable groups (e.g., older adults or those with chronic physical conditions)[77,78], people with mental health conditions may face distinct and compounding barriers during heat events. These include barriers to accessing care and stigma that hinders timely support[5,73]. Future plans should prioritize a range of appropriate interventions that address the unique vulnerability of this population and span the levels of the socioecological model, ensuring that efforts at each level are interconnected and mutually reinforcing. These can include promoting adequate hydration, nutrition, the use of breathable clothing, and cool sleeping environments to improve the quality of sleep at the individual level [60]. In general, individual-level interventions may also involve enhanced psychological support during extreme heat events, including training for first responders and healthcare providers in mental health care, such as psychological first aid (PFA) [79–81], and expanding the availability of mental health services at cooling centers. Relationship-level interventions can include training neighbors to check on other vulnerable neighbors during heatwaves, such as the elderly, those living alone, or individuals with pre-existing mental health conditions, as proposed in two of the plans [60]. Future plans should also include community-level strategies, such as building social networks and peer support initiatives, to promote community cohesion and help mitigate isolation and stress often exacerbated by extreme heat [74,75,82]. Mitigating social isolation is particularly important in the context of mental health conditions, as social isolation can create additional barriers to accessing support [57]. Community awareness programs can inform the public about the signs of heat stress, its potential effects on mental health, and effective strategies for staying cool [60]. At the societal-level, government and community leaders should support individual and community resilience before extreme weather events occur to increase an individual’s capacity to respond. Interventions should be tailored to different cultural and demographic contexts and draw on a diverse range of mental health expertise.

The analysis highlights a significant gap in the monitoring and evaluation of mental health outcomes within existing plans. Future initiatives should develop specific metrics to evaluate mental health outcomes during extreme heat events, include the monitoring of mental health outcomes within national level heat-health surveillance systems (e.g., by providing mortality data disaggregated by health outcomes), as well as evaluate the effectiveness of mental health relevant interventions. These metrics would help to guide improvements in future plans as well as provide context-specific data for policymakers to understand the full scope of climate-related health risks and enable appropriate frameworks and checklists for policymakers to use when developing the plans.

While we call for the integration of appropriate interventions in future plans, it is important to recognize that there is currently limited evidence on what interventions work, when, where, and for whom [83]. The limited inclusion of mental health interventions in existing heat-health action plans may, in part, reflect this underdeveloped evidence base. Research investment is needed to generate the evidence to support policymakers to act. Furthermore, relevant interventions are not always widely known, highlighting the need for efforts to collate and share this knowledge globally, through initiatives such as the Connecting Climate Minds Global Online Hub [84].

Limitations

This study has several limitations. First, in identified plans, there was an overrepresentation of high-income countries and an overrepresentation of plans from India, covering 90% of plans (35 plans) from low-middle income countries. However, available plans from low-income countries were either not accessible or did not meet our eligibility criteria, suggesting a potential lack of substantial development of heat-health plans in these countries. Second, the lack of standardized reporting on mental health within plans may have led to underreporting or misinterpretation of mental health impacts and interventions. There was a lack of specificity of language that precludes targeting support. Third, potential translation issues may have resulted in the misinterpretation of mental health terminology or a lack of nuanced understanding of mental health issues in some plans. Fourth, our review did not assess the implementation status of the identified plans, and therefore does not capture the extent which policy guidance has translated into practice. Finally, plans were downloaded between April 4 and July 30, 2024, and additional heat-health action plans may have been released since then, which would not have been captured in this review.

Conclusion

Global frameworks such as those from the WHO and IPCC emphasize the need for integrating mental health services into climate response efforts and mobilizing funding for these services [29,30]. Our review underscores the need for future plans to include targeted interventions and secure resources aimed at supporting this integration, particularly as extreme heat events are projected to increase under climate change. Addressing the underrepresentation of mental health consideration in health planning will ensure more comprehensive responses to heat events and improve communities’ capacities to cope with the psychological impacts of climate change.

Data Availability

The heat-health action plans used for this analysis are available online via the Global Heat Health Information Network and have been individually linked in Supplementary Table 2.