The World Isn’t Ready for the Mental Health Toll of Extreme Heat

By Madhusree Mukerjee edited by Dean Visser

A man walks with an umbrella to protect himself from the heat as a yellow alert is issued by the U.K. Health Security Agency (UKHSA) because of increasing temperatures in London on June 25, 2024. Rasid Necati Aslim/Anadolu via Getty Images

The coming summer is forecast to be a scorcher across the U.S. And climate scientists predict that at least one of the next five years will beat 2024 as the hottest year ever recorded globally. As heat waves are getting more intense and prolonged, their effect on the mind and body are also becoming more dire. Children and older people, as well as those who work outdoors, are most at risk. So are those with mental health disorders.

Heat waves are the single highest cause of weather-related deaths in the U.S., where an estimated 1,300 fatalities from heat stroke and other temperature-related complications occur every year. Even those who survive a period of extreme heat may suffer serious neurological or other mental-health-related disorders.

A new study published in Current Environmental Health Reports finds that the world is startlingly unprepared to deal with the mental health consequences of climate change. Of 83 action plans for heat-related health problems that were reviewed for the study, fewer than a third acknowledged the mental health effects of extreme or prolonged high temperatures. And only a fifth of these plans outlined specific actions to deal with contingencies such as increased hospitalizations for mental health disorders.

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How does extreme heat affect the brain?

The human body operates optimally at 98.6 degrees Fahrenheit (37 degrees Celsius). If a person doesn’t drink enough water when the weather is hot and dry, the body becomes dehydrated, the blood thickens, and the heart may not be able to pump enough oxygen to the brain. Additionally, the human brain burns up 20 percent of the body’s energy and therefore needs to dissipate heat efficiently. In hot and humid conditions, sweating cannot cool the body and brain enough. This can lead to heat exhaustion, which has symptoms such as weakness, dizziness and headaches and, in extreme cases, heat stroke—which can then trigger delirium and loss of consciousness. A significant fraction of heat stroke survivors suffer neurological complications.

Exposure to extreme heat can also increase the risk of suicide and can worsen schizophrenia, epilepsy, anxiety, depression, substance use disorder, neurodegenerative disorders (such as Alzheimer’s disease) and negative emotions such as fear and anger. It may worsen sleep, which, in turn, can increase fatigue and impair cognition. Alcohol and recreational drugs, as well as certain medications used to treat mental illness, such as antidepressants, tranquilizers and antipsychotics, also appear to increase mental health vulnerability to heat.

Studies find an increased risk of suicide and epileptic seizures during heat waves, as well as an increase in hospitalizations and emergency-room visits for mental health disorders. Heat can also disorient thinking, making people slow to realize that they need to seek shelter or help.

Who is most at risk?

The most vulnerable are those with existing mental health disorders. Disturbingly, prolonged heat waves also appear to worsen the risk among young children—and even the unborn—of developing mental health ailments in the future. Older people may also be particularly affected, such as by accelerated dementia and Alzheimer’s.

At particular risk are vast populations around the world who live without air-conditioning, including poor or homeless people and those who work outdoors, such as on farms.

What can be done?

The authors of the new Current Environmental Health Reports study point to interventions at several levels to help communities and individuals most at risk of climate mental health impacts. These can include public awareness campaigns, such as warning people about the mental health risk of consuming alcohol or other drugs during heat waves. Other interventions include establishing community cooling shelters for heat emergencies and increasing monitoring of mental health patients during heat waves. Extreme heat is here to stay, at least for the foreseeable future. We need to prepare people and communities to reduce the risk of mental health emergencies.

IF YOU NEED HELP

If you or someone you know is struggling or having thoughts of suicide, help is available. Call or text the 988 Suicide & Crisis Lifeline at 988 or use the online Lifeline Chat.