What Extreme Heat Does to Your Brain

Extreme heat is ravaging parts of the United States and around the globe. High temperatures are not only putting communities at risk of heat-related illnesses, but they can also impair brain function.

In a recent commentary published by The Lancet Neurology, an international group of researchers wrote that rising temperatures can challenge the human capacity to maintain body temperature and disrupt nervous system functions. Climate change will also likely exacerbate neurological and psychiatric disorders, including Alzheimer’s disease and schizophrenia.

Studies have shown that cognitive performance starts to decline at around 79 degrees. Some researchers suggest that at elevated temperatures, parasympathetic nervous system activity and blood oxygen saturation levels could both be lower, leading to reduced cognitive function.

Kimon Bekelis, MD, the chair of neuro-interventional services at Catholic Health on Long Island, said it’s not entirely clear why cognitive function takes a nosedive in extreme heat, but current research is focused on the connection between neurotransmitters and heat exposure.

“Our nervous system is a collection of cables that transmit electricity and signals across the body. But electrical conduction, of course, can be affected by heat. And we know that from physics experiments, so we’re extrapolating that,” Bekelis told Verywell.

Bekelis added that it’s important for those who are outside during heatwaves to keep tabs on their mental health.

“Depression, anxiety, things of that nature can intensify with heat,” he said. “If somebody is exposed to so much heat, they could suffer from heatstroke. And there’s the physical manifestations of extreme heat in the body, not just the brain.”

Some medications, such as antipsychotics, can interfere with how the body regulates heat. Disabilities such as spinal cord injuries can also lead to decreased function in regular bodily tasks, such as sweating, which can stop occurring below a person’s line of injury.

How Should You Protect Yourself from Extreme Heat?

During heatwaves, try to stay in places that are air-conditioned and make sure you’re well-hydrated. If you have thermal regulation issues, solutions like cooling vests can also bring your temperature down.

Bekelis said while there are ongoing discussions about a safe or optimal temperature range for the brain, there’s no reliable data point when it comes to individual safety. If you live in warmer climates, chances are your body would have adjusted to the heat.

“If you live in Florida, the average temperature that you’re exposed to will be a lot higher. That doesn’t mean, of course, that the Floridian brain stops functioning as well,” Bekelis said. “It’s all about homeostasis. If folks are exposed to a particular temperature all the time, the challenge comes from the extremes of temperature.”

Jun Wu, PhD, a professor of environmental and occupational health at the University of California-Irvine, said that cooling shelters are extremely limited in availability, and not everyone can get easy access to them.

“Also, the locations are not distributed in the population where they need the cooling centers the most,” Wu told Verywell. “The operation hours may not be ideal. For instance, they use libraries and senior centers, and the hours are limited—they exist in the operation hours of these facilities.”

Policy and infrastructure changes are necessary for reducing heat-related health risks, she added.

“Local government, especially, can really do something,” Wu said. “Planting trees is relatively simple. Also, painting a lighter color of roof and road—those things are relatively easy to do and may have multiple benefits. Green planning, in addition to reducing the heat, can also help with reduced air pollution.”