A banner at the inaugural Earth Day, New York City, 22nd April 1970. Earth Day is held annually to raise awareness of environmental issues.  (Photo by Archive Photos/Getty Images)
WATCH: See how the climate crisis has affected Earth
03:56 - Source: CNN

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CNN  — 

As the climate crisis gets worse, we know of farmers whose crops are drying up and people who lose their homes due to rampant wildfires.

But there’s another group for whom the climate crisis is a potentially lethal threat — people with mental health problems such as schizophrenia, bipolar disorder or anxiety.

And this threat has already become reality for some people. During a record-breaking heat wave in British Columbia in June 2021, 8% of people who died from the extreme heat had been diagnosed with schizophrenia, according to a March study. That made the disorder a more dangerous risk factor than all other conditions the authors studied, including kidney disease and coronary artery disease.

People with certain mental health problems are more at risk for experiencing the dangers of the climate crisis, experts say.

“Until climate change gets under control, things are only going to get worse unfortunately,” said Dr. Robert Feder, a retired New Hampshire-based psychiatrist and the American Psychiatric Association’s representative to the Medical Society Consortium on Climate and Health. “As the temperature keeps increasing, these effects are going to be magnified. There’s going to be more storms, more fires, and people are going to be more worried about what could happen because a lot more things are happening.”

Rising temperatures have also been associated with suicide attempts and increased rates of mental health-related emergency department visits, several studies have found. And long-term exposure to air pollution — which the climate crisis can worsen by adding more particles from droughts or wildfires — has been linked with elevated anxiety and an increase in suicides.

What’s going on in the brains of people with schizophrenia or other conditions is just one factor that makes them more vulnerable to extreme heat, air pollution and stress, experts said — and in need of support from loved ones, surrounding communities and policymakers.

Extreme heat and mental health

What makes some psychiatric patients more susceptible to the harms of extreme heat — such as heatstroke or death — begins in a part of the brain called the anterior hypothalamus. Think of it as the body’s thermostat.

“That’s the part of the brain that is working to tell you — when you’re too hot or you’re too cold — to begin shivering, to begin sweating,” which is the body’s cooling mechanism, said Dr. Peter Crank, an assistant professor in the department of geography and environmental management at the University of Waterloo in Canada. Crank was the lead author of a March study on associations between temperatures in Phoenix, Arizona, and hospital admissions of people with schizophrenia.