As climate change continues to intensify, so too does the urgency to understand its far-reaching effects on human health—particularly on the brain, one of the most complex and sensitive organs in the body. New research is revealing that rising global temperatures and prolonged heatwaves are not just environmental or infrastructural challenges—they’re direct threats to neurological health, influencing everything from seizures to cognition, mental well-being, and the progression of neurodegenerative diseases.
The Brain’s Battle Against Heat
The human brain is uniquely vulnerable to heat. Although it represents only about 2% of total body weight, it consumes roughly 20% of the body’s energy, generating considerable heat as it operates. The body relies on thermoregulation, a process orchestrated by the brain itself, to keep its temperature within a very narrow and safe range. But this system begins to fail when external temperatures rise too high or stay elevated for too long.
During heatwaves, the strain placed on the brain’s ability to maintain balance can lead to serious neurological consequences. Individuals with epilepsy, Dravet Syndrome, or multiple sclerosis (MS) are particularly vulnerable. Many of these conditions involve impaired heat dissipation, compromised nerve function, or reliance on medications that disrupt temperature regulation—increasing the risk of heatstroke or seizures.
According to the National Institute of Neurological Disorders and Stroke, even small disruptions in brain temperature can interfere with neurotransmitter function and neural communication, leading to cognitive decline, mood disturbances, or worse.
Heat and Cognitive Decline in Older Adults
Older populations are at heightened risk during extreme heat events. Studies have found that hospitalizations and mortality rates increase among those with dementia during heatwaves. Aging impairs the body’s natural ability to cool itself, while cognitive impairment can lead to poor decision-making during high temperatures—such as forgetting to hydrate or neglecting to use cooling devices.
Furthermore, elevated heat exposure has been linked to an increase in stroke incidence and mortality. A 2022 study across 25 countries found that on the hottest days, for every 1,000 deaths from ischemic stroke, an additional two were directly attributable to extreme heat. Given that strokes are already a leading cause of death and disability globally, this increase represents a significant public health concern.
As detailed by the World Health Organization, the rise in heat-related neurological events is also deepening existing health inequalities. Lower-income populations, who often lack access to air conditioning or adequate housing, are disproportionately affected—particularly in already vulnerable countries facing rapid climate shifts.
Impacts on Infants, Children, and Developing Brains
Emerging data indicates that climate change may be affecting neurodevelopment in children, beginning even before birth. Extreme heat during pregnancy has been associated with a 26% increase in preterm births, which in turn raises the risk of cognitive and developmental delays. These effects are particularly troubling given that 130 million births occur annually—many in regions already experiencing extreme heat.
A systematic review published in 2020 in The Lancet found consistent evidence linking elevated prenatal heat exposure with adverse outcomes for the brain. Premature birth, low birth weight, and exposure to maternal heat stress may compromise brain formation during critical developmental windows.
Additionally, children with existing neurological or behavioral conditions such as autism, ADHD, or seizure disorders are more likely to experience symptom exacerbation during heat events. Heat-related sleep disruption is another factor, as poor sleep significantly worsens behavior, learning capacity, and emotional regulation in young people.
Mental Health, Medications, and the Hot Brain Phenomenon
Beyond neurological conditions, excessive heat is also influencing mental health. During extreme temperatures, studies have recorded increases in aggression, depression, anxiety, and even suicidal behavior. The mechanism is multifaceted: heat disrupts sleep, lowers mood, and may interfere with the metabolism of medications used to treat mental disorders.
According to the Centers for Disease Control and Prevention (CDC), many psychiatric medications impair the body’s ability to regulate temperature, leaving patients more susceptible to hyperthermia and heat-related mortality. In patients with schizophrenia, bipolar disorder, or major depressive disorder, this can lead to hospitalization or fatal outcomes during heatwaves.
Moreover, the blood-brain barrier, which protects brain tissue from pathogens and toxins, becomes more permeable at high temperatures. This could increase the risk of viral encephalitis and other infections, particularly as mosquito-borne diseases like Zika, dengue, and chikungunya expand into new regions due to warming climates.
The Environmental Protection Agency (EPA) warns that prolonged climate stress could eventually impair brain function even in individuals without preexisting neurological conditions—a phenomenon some researchers refer to as the “hot brain.” This suggests a future where all humans may face new cognitive risks if warming trends continue unabated.
A Call for Protection and Prevention
As climate change progresses, researchers stress the urgent need to identify who is most vulnerable—and why. Factors like genetic predisposition, chronic illness, and socioeconomic status all influence how severely one is affected by heat. Developing targeted strategies such as early warning systems, public cooling centers, and heat-mitigating policies will be critical to protect the most vulnerable populations.
The evidence is clear: climate change is already affecting our brains. It is altering behavior, worsening diseases, and adding a new layer of complexity to the global health crisis. And as global warming accelerates, the burden on our brains may only increase.
