There is a growing recognition in the scientific community that climate change is not merely an environmental or economic crisis — it is a public health emergency of the first order. What has been slower to gain traction, however, is the understanding that climate change is also a brain health crisis. As the Journal of Global Health Neurology and Psychiatry enters its fourth year of publication, we dedicate this editorial to what we believe is the most consequential and underexplored frontier at the intersection of planetary health and neuropsychiatric medicine: the multi-pathway impact of climate change on the human brain and mind, and the profound inequities that determine who bears the greatest burden of that impact.
The relationship between climate and mental health is not new to science. Seasonal patterns of mood disorders have been documented for decades, and the psychological sequelae of natural disasters — depression, post-traumatic stress disorder, complicated grief — are well established in the literature. What is new is the scale, the acceleration, and the systemic nature of what we now face. The Intergovernmental Panel on Climate Change Sixth Assessment Report, published in stages through 2022, described with unprecedented clarity the mental health consequences of climate-related exposures, framing them as a significant and growing component of the overall burden of climate change on human wellbeing.1
Heat, the Brain, and the Neurological Toll of a Warming World
Among the most direct pathways through which climate change affects brain health is extreme heat. Ambient temperature exerts well-documented effects on neurological and psychiatric functioning. Heat stroke and hyperthermia cause acute encephalopathy and, in severe cases, permanent neurological injury. At sub-clinical temperatures, cognitive performance — including attention, executive function, and processing speed — declines measurably, with implications for workplace safety, educational attainment, and quality of life.2
The psychiatric effects of heat are equally concerning. A landmark study analysing hospital admission data across multiple countries found a significant association between ambient temperature and emergency psychiatric admissions, with heat exposure linked to increased rates of psychosis exacerbation, suicide attempts, and substance use crises.3 Antipsychotic and mood-stabilising medications commonly prescribed to patients with severe mental illness impair thermoregulation, placing this already-vulnerable population at compound risk during heatwaves. For low- and middle-income countries (LMICs) in tropical and subtropical regions — where air conditioning is unavailable to most of the population and where psychiatric medication is often the only available treatment — this represents an urgent and largely unaddressed clinical emergency.
Disaster, Displacement, and the Epidemic of Ecological Grief
Beyond heat, the neuropsychiatric consequences of climate-related disasters — floods, wildfires, prolonged droughts, and cyclones of increasing intensity — are accumulating in the evidence base with disturbing consistency. Systematic reviews of post-disaster mental health outcomes document rates of PTSD ranging from 30% to over 50% in directly affected populations, with depression, anxiety, and substance use disorders also substantially elevated.4 Children and adolescents are particularly vulnerable: exposure to disaster during developmentally sensitive periods has been associated with lasting effects on stress reactivity, emotional regulation, and cognitive development.
Climate-related displacement introduces additional neuropsychiatric risk. The global number of people forcibly displaced by weather-related disasters exceeded 26 million in 2023, according to the Internal Displacement Monitoring Centre — a figure that does not include the slower-onset displacement driven by sea-level rise, desertification, and chronic water insecurity.5 Displaced populations face the combined psychological burden of loss, uncertainty, severed social networks, and exposure to violence and exploitation, in contexts where mental health services are almost invariably absent or overwhelmed.
A subtler but increasingly documented phenomenon is what researchers and clinicians have come to call ecological grief or climate anxiety — the chronic psychological distress arising from awareness of, and helplessness in the face of, environmental destruction. Once dismissed as a marginal concern, climate anxiety has now been documented at clinically significant levels in representative population samples across multiple continents, disproportionately affecting young people and those with pre-existing vulnerability to anxiety disorders.6 This is not a pathologisation of a rational response to genuine threat; it is a recognition that when the stress is unrelenting, pervasive, and without clear resolution, its psychological consequences require clinical and societal attention.
The Neuroinflammatory Bridge: Air Pollution and Brain Disease
Climate change and air pollution are deeply intertwined: rising temperatures worsen ozone formation, wildfire smoke degrades air quality across entire continents, and the fossil fuel combustion driving climate change is simultaneously the primary source of fine particulate matter (PM2.5) that enters the human brain via the olfactory pathway and systemic circulation. The neurotoxicity of air pollution has moved from hypothesis to established science with remarkable speed over the past decade. Exposure to PM2.5 has been associated with accelerated cognitive decline, increased risk of dementia, higher incidence of stroke, and — in children — measurable reductions in grey matter volume and cognitive test performance.7
The neuroinflammatory mechanism is now reasonably well characterised: particulate matter induces microglial activation and sustained neuroinflammation that, over years and decades, contributes to the neurodegenerative processes underlying Alzheimer’s disease, Parkinson’s disease, and cerebrovascular pathology. For the global neurological community, this means that addressing climate change and reducing fossil fuel combustion is not merely an environmental imperative — it is a dementia prevention strategy of the first order.
Equity at the Core: Who Suffers Most
Every pathway described above operates within a landscape of radical inequity. The countries contributing least to cumulative greenhouse gas emissions — predominantly LMICs in sub-Saharan Africa, South and Southeast Asia, and the Pacific — face the greatest climate-related neuropsychiatric risks, by virtue of geographic exposure, economic vulnerability, inadequate infrastructure, and the near-total absence of mental health and neurological services that might buffer the impact. The phrase “climate injustice” is sometimes deployed as rhetoric; in the context of brain health, it describes a measurable, documented, and morally intolerable reality.
A comprehensive review published in 2024 mapped the intersection of climate vulnerability indices and mental health service availability across 140 countries, finding a strong inverse relationship: the countries most exposed to climate-related mental health risk had, on average, fewer than two mental health workers per 100,000 population — compared to more than 50 in the least-exposed high-income countries.8 This gap will not close without deliberate, sustained, and equitably distributed global investment.
A Research Agenda for a Warming World
The Journal of Global Health Neurology and Psychiatry calls on the global research community to treat the neuropsychiatric dimensions of climate change as a scientific priority commensurate with the scale of the problem. This means longitudinal cohort studies that capture the neurological and psychiatric consequences of climate exposures across the life course; intervention research testing scalable, culturally adapted models for post-disaster mental health support; mechanistic studies elucidating the pathways through which heat, pollution, and psychosocial stress interact to accelerate neurodegeneration; and health systems research on how to build neuropsychiatric resilience into climate adaptation planning.
We are aware of the irony that much of this research must be conducted in the settings most affected — and that those settings are also the least resourced to conduct it. Addressing this requires not only funding but a fundamental reorientation of how global health research partnerships are structured, compensated, and governed. The Journal of Global Health Neurology and Psychiatry will continue to prioritise research from and about these settings, and to hold itself and its authors to the highest standards of equity, rigour, and relevance.
The climate crisis will define the coming decades of global health. It will not spare the brain. Our field has both the responsibility and the capacity to respond — but only if we act with the urgency, the humility, and the solidarity that the moment demands.