Heat is agonizing, something many in the U.S. were reminded of this month as an October heat wave shattered seasonal heat records. 

But high temperatures can also be fatal.

As a New York City-based medical toxicologist and physician, Adam Blumenberg has seen firsthand the deadly impact of heat exposure. He can still remember a young patient who became delirious when his body temperature climbed to about 108 F. 

“That temperature can kill someone within minutes if not brought down into a safe range,” he cautioned. The patient was administered a sedative as Blumenberg’s team covered his body with ice and put him on a ventilator. “He was able to return home after a couple of days in the intensive care unit,” Blumenberg recollected. 

As someone who routinely cares for individuals facing heat-associated illnesses, Blumenberg is particularly worried for patients who cannot recognize the signs of overheating and take the necessary precautions. Clinicians and physicians such as Blumenberg have flagged how extreme weather events such as heat waves can be especially catastrophic for people with schizophrenia, a chronic mental illness and severe thought disorder. The medications that people with schizophrenia consume, along with the conditions in which they live and the stigma they experience, exacerbate their risk, according to physicians.  

Distress signals

In the last decade, heat waves have increased in frequency and intensity due to climate change. This summer alone, an estimated 255 million Americans were exposed to a life-threatening heat dome. 

While 2024 now holds the record for being the hottest year yet, the average rate of heat waves has tripled in the U.S since the 1960s. Scientists estimate that by 2060, more than 200 major American cities will face an average spike in temperature of about 3.6 degrees. Once mild summers in American cities such as Casper, Wyoming, and Billings, Montana, will be equivalent to temperatures currently seen in the Southwest. 

The oppressive heat wave that gripped New York City in June led to a spike in emergency room visits, with 341 trips attributed to heat-related illnesses. From 2018 to 2022, an estimated 525 New Yorkers died annually due to heat, with hundreds more experiencing “heat-exacerbated deaths” caused by heat aggravating an underlying illness, according to city data. 

Recently, researchers and physicians have started to look at the risks posed by rising temperatures to various marginalized communities. People with mental health illnesses have stood out. 

At particular risk are people with schizophrenia, who are 1% of the American population, or 3.7 million people as of 2023. In part, people with this particular mental illness experience symptoms, such as delusions, hallucinations, and other cognitive impairments, which thwart their ability to sense their body is overheating and take action to remove clothing, for example, or hydrate and move to a cooler location. In short, while there may be nearby cooling centers or water sources, people with schizophrenia can experience cognitive challenges in accessing relief. 

One of the earliest signs of an advancing heatstroke is when your body temperature rises beyond the threshold of 104 F. The first signs of illness are usually cramps, followed by dizziness and heavy sweating. Physicians flag the importance of early intervention for each of these stages to abate the risk of heatstroke and death. But as Blumenberg pointed out, among people with schizophrenia, acute exhaustion and discomfort cannot always be described to medical professionals because the distress signals haven’t been clocked, even if they are advanced. 

This heightened risk for people with schizophrenia was evident during the 2021 heat dome in British Columbia, Canada, which killed 619 people. Despite constituting 1% of the Canadian population, 97, or 16%, of the people who died during this period of extreme heat were individuals diagnosed with schizophrenia. 

In a study published last year, researchers in Canada aimed to better understand this disproportionate health burden. Through interviews conducted between October and February 2024, researchers found that symptoms of paranoia and delusion, often associated with schizophrenia, were a major factor that restricted a patient’s ability to seek relief from the heat.

The study’s findings suggest that some had difficulty interpreting bodily sensations accurately. 

“I think interpreting what you feel in your body is hard. For many years, I’ve dealt with some tactile hallucinations. So then you’ll feel vibrations, if you hear voices talking in my knees, or, vibrations talking in different parts of my body,” one of the interviewees told sociologist Liv Yoon, a co-author of the study. “So then, if you feel extreme heat, [you wonder] ‘What does this mean?’ … I don’t understand. I don’t know how to listen to what my body is telling me.”

Dr. Siqi Xue, a psychiatrist and associate scientist at the Canada-based Centre for Addiction and Mental Health, told Prism that some studies also suggest that people with schizophrenia are more likely to die than people with cardiac [or] respiratory conditions.

The U.S also saw an increased rate of hospitalization among people with schizophrenia due to both extremely hot and extremely cold temperatures. While other demographics of adults, including the elderly and unhoused, are at a higher risk of heat exposure, experts say these vulnerable populations are also often living with schizophrenia. In Phoenix, for example, unhoused people—including those with schizophrenia—are 400 times more likely to die from heat than the overall population. 

Compounded vulnerabilities  

Only one state in the country—Arizona—has an office for addressing heat risks, and even so, the word “schizophrenia” does not appear in the region’s heat response plan, David Hondula, who leads the city’s Office of Heat Response and Mitigation, told Science in 2023. More broadly, the side effects of common antipsychotic medications prescribed to people with schizophrenia, including olanzapine, risperidone, and haloperidol, create an additional challenge—even for experts and health care professionals who understand the links between schizophrenia and heat stress. 

According to physicians, people with schizophrenia are typically prescribed these drugs to help “suppress psychotic symptoms” such as hallucinations, delusions, or disorganized thinking. 

These medicines also have anticholinergic properties, which means they block a chemical messenger called acetylcholine. Acetylcholine plays a crucial role in causing glands to produce sweat. Any roadblocks to this neurotransmitter can interfere with the body’s thermoregulation. This is the body’s way of dissipating heat through sweating and then cooling down, so disrupted thermoregulation puts patients in danger of overheating and, in rare cases, increases the risk for heatstroke. 

Blumenberg told Prism that medications regularly prescribed to people with schizophrenia can also increase muscle activity and tension, meaning that even if a person isn’t engaging in strenuous activity, the increased tightness caused by the medication tricks their body into thinking they are doing work and burning off energy, further generating heat.

It’s important to note that between 5% and 25% of patients with schizophrenia partially or totally do not respond to antipsychotic drug therapy. In these cases, patients are considered to have treatment-resistant schizophrenia (TRS). 

Dr. Robert Laitman, a nephrologist, gerontologist, and an internal medicine physician at Bronx Westchester Medical Group in New York, became interested in schizophrenia after his son Daniel was diagnosed in 2006, which shaped his decadelong research into clozapine, the only U.S. Food and Drug Administration-approved drug for TRS.

Laitman is also an athlete who goes on runs with his patients, two of whom are currently on clozapine. “This allows them to do great; they take the drug at night and run during the day, and they have a good ability to sweat,” he explained. According to Laitman, clozapine doesn’t disrupt thermoregulation as much as other medications commonly used for schizophrenia.

As a physician, Laitman treats children with schizophrenia and recollects hearing of chilling encounters in which children inadvertently endangered themselves. 

“It’s a hot summer day, and they’re sitting on a bench and enjoying it. They’re feeling good. But they continue sitting there, slowly getting dehydrated, unaware of their thirst mechanism,” he said. Once dehydrated, a person’s ability to thermoregulate is further restricted, and related symptoms such as heat burn and heatstroke can escalate very quickly. Depending on the temperature and humidity, without intervention, burns can develop in a matter of seconds, and heatstroke, which can potentially lead to organ dysfunction, can occur in a few hours, Latiman cautioned. 

Dr. David G. Frederick, the medical director of the Appleton Residential Program at McLean Hospital in Belmont, Massachusetts, told Prism that at his long-term residential mental health program, they have been able to make certain modifications to decrease risks from extreme temperatures. In terms of adjusting medications, he maintained that medical professionals need to weigh the risks and benefits. 

“Reducing the dose of medication to help with thermoregulation can increase the risk of symptom recurrence,” Frederick said. Ultimately, he said, physicians are compelled to weigh these risks against each other. “We try to avoid making medication changes to solve issues of thermoregulation when doing something else—like using fans, cold water, air conditioning, etc.—will be effective without increasing psychiatric risk,” he said.

Social isolation and exclusion also compound vulnerability, as stereotypes and stigma regarding mental illness further restrict patients’ ability to seek medical help. While unpacking the risks that people with schizophrenia face, the authors of the 2021 heat dome study wrote that patients they interviewed felt “deterred from seeking medical care or public resources due to past negative experiences and social stigma.”

“If a person [with schizophrenia] in [British Columbia] has heat-related illness, and if they go to an ER, they’re likely to be triaged last, even though it’s urgent, even though they could die, they’re likely to be triaged last,” said one patient interviewed as part of the study. 

At Boston’s McLean Hospital, patients are part of a residential program that offers comprehensive schizophrenia care. It is among the few programs in the country where the campus also shares grounds with a psychiatric hospital. This makes it easier for the staff to routinely check in on patients when the temperatures soar or drop, explained Frederick. For patients who are unhoused and unemployed, Yoon said these circumstances typically cut them off from care, kinship, and critical resources, such as air conditioning, which increase their vulnerability.

This is reflected in the study that Xue was part of, which included interviews with clinicians who work with people diagnosed with schizophrenia. Many expressed frustration at the circumstances facing their patients, who are already people who tend to face poverty, housing instability, and social exclusion. “And yet they are the people who are disproportionately suffering from heat as well,” Xue said. 

According to Yoon, health care professionals themselves also face the challenge of not always being able to distinguish between schizophrenia symptoms and heat-stress symptoms. Frederick said that when someone is presenting with irritability, mood fluctuations, or trouble sleeping, it could be a side effect of medication. It could also be that they’re too hot, he added. At his hospital, Frederick’s team sees firsthand that many stressors contribute to the distress that patients with schizophrenia face, including stressors that are familial and social. 

“There is often a lot of overlap with these sorts of things, so it can be very hard to tease apart because they [symptoms] look the same,” he said.

Mapping the science  

According to physicians who spoke to Prism, people with more severe and chronic mental health illnesses suffer more from physical health consequences due to climate change. With heat waves associated with a 9.7% increase in mental health-related hospital visits, much of the burden of providing evidence-based guidance and early detection of potential heat stress falls on clinicians in emergency rooms. 

Laitman said health care professionals who treat patients with schizophrenia and who are aware of the heat-related risks should effectively communicate that information to patients so they are more aware of what to be mindful of when temperatures rise. 

Xue has been involved in efforts to address the vulnerabilities of people with schizophrenia. She worked with a clinical pharmacist to write an educational piece about medications in the context of extreme heat. The writing was turned into a pamphlet that was then circulated to psychiatrists and private care physicians. It was particularly important that this information landed in the hands of clinicians, who help patients to carry out actions they may struggle with due to functional limitations.

Xue’s peers are now educating themselves on how to better help their patients with schizophrenia. Many have taken personal initiative to more regularly check in with their vulnerable patients. Xue said this means that some of her colleagues even visited homeless shelters to see their patients and educate the shelter staff on signs of heat stress.

The Centre for Addiction and Mental Health, where Xue works, is also among the few mental health centers in Canada to roll out a heat wave plan for safely discharging patients who do not have stable housing. This is particularly helpful to those with schizophrenia, who are often treated during months when the heat rises. 

Efforts are also underway to design emergency plans for safe outreach and discharge with the help of clinicians and people with schizophrenia. More broadly, Xue hopes that the local community can work toward ensuring that landlords adhere to a maximum indoor temperature or otherwise offer free access to cooling devices. She told Prism that these are important steps toward lowering heat-risk among people with schizophrenia.

As data-informed interventions and policy changes gain momentum to reduce the disastrous impacts of climate change, in part, Xue attributes these efforts to researchers who for years worked diligently to map the science between psychosis and extreme heat. 

But these scientific efforts are now facing new challenges. Since President Donald Trump returned to the White House, his administration has taken an aggressively antiscience stance. He has frozen millions of dollars in research grants and canceled $11.4 billion in post-COVID-19 funding that was allocated for mental health and other programs.  

According to the National Alliance on Mental Illness (NAMI), the Trump administration’s budget for fiscal year 2026 also slashes almost $18 billion from the National Institute of Health and nearly $1.1 billion from programs currently under the Substance Abuse and Mental Health Services Administration. These actions will halt even more critical research and programs that were specifically devised to help people with mental illness “get well and stay well,” said Hannah Wesolowski, NAMI’s chief advocacy officer, in a statement. Wesolowski also said the Trump administration’s actions will put “people out of work, on the streets, and in jails and emergency rooms.” New York Gov. Kathy Hochul has also made her frustration with the cuts public, noting the “devastating” impact it will have on people with mental health issues.

“People with preexisting mental illness have been consistently identified as an at-risk group, and yet we don’t know of any key adaptation plan that explicitly considers their unique needs,” Xue said, underscoring the need for consistent and targeted scientific inquiries that can prevent or reduce heat mortality among people with schizophrenia. “The lack of research funding will affect this research gap further.”

Editorial Team:
Tina Vasquez, Lead Editor
Carolyn Copeland, Top Editor
Stephanie Harris, Copy Editor