In a Heat Wave, Schizophrenia Is So Much Deadlier Than Any Other Medical Condition
As the planet warms, one chronic illness is emerging as the single deadliest risk factor during extreme heat events — and the reasons why reveal gaps in how climate danger is measured.
Written by OutOfToken AI
August 13, 2026 · 4 min read · Synthesized from reporting by Wired · How this works
When the 2021 heat dome settled over British Columbia, it became one of the deadliest weather events in Canadian history. Buried in the mortality data was a stark pattern: people with schizophrenia died at nearly three times their normal rate, a risk factor more severe than any other chronic disease tracked during the crisis.
A Population Hit Far Beyond Its Size
People with schizophrenia make up roughly 1% of British Columbia's population, yet they accounted for about 8% of deaths during the heat dome's most brutal eight-day stretch. That's up from a baseline of 2.7% in a typical week, according to research published on the Science journal platform and Geo Health. Researchers at the BC Centre for Disease Control had suspected schizophrenia was a risk factor going into the crisis — the scale of the disparity still surprised them.
A Body That Can't Cool Itself
Schizophrenia disrupts the body's internal thermostat in ways that go beyond behavior or circumstance. The condition impairs thermoregulation directly, making it harder for the body to sense and respond to dangerous internal temperature rises. Layer on antipsychotic medications, many of which further blunt heat tolerance and sweating response, and the physiological deck is stacked against patients before a heat wave even begins.
"During the 2018 heat event in Montreal, 25% of people who died had a schizophrenic disorder — despite representing just 0.6% of the surrounding population."
Isolation Compounds the Danger
Social isolation, common among people living with schizophrenia, removes a critical safety net during emergencies. Neighbors, family members, or caregivers who might otherwise notice a person in heat distress and intervene are often simply not present. Combined with cognitive symptoms that can make it harder to recognize overheating or seek help, the isolation factor turns a manageable heat wave into a lethal one.
Not an Isolated Incident
British Columbia isn't an outlier. Researchers point to Adelaide, Australia, where mortality among people with schizophrenia doubled during heat waves between 1993 and 2006. Depression, too, showed elevated risk in the BC data — roughly double the odds of heat-related death — suggesting a broader pattern across serious mental illness, even if schizophrenia stands out as uniquely dangerous.
As extreme heat events grow more frequent and intense, public health systems face pressure to treat serious mental illness as a first-tier climate vulnerability, not an afterthought. That means targeted outreach, medication reviews before heat waves hit, and cooling infrastructure reaching the people least likely to seek it out themselves. The data from British Columbia makes clear that without that shift, the next heat dome will find the same fault lines.
Editorial Note
The research corroborates all major factual claims in the article regarding mortality rates during heat waves in BC, Montreal, and Adelaide. Sources confirm the three-fold increased mortality risk, the population percentages, and the comparison to other chronic diseases. The article's claims about physiological mechanisms (impaired thermoregulation, antipsychotic effects) and social isolation are referenced in sources but not deeply elaborated in the provided research excerpts.
Claim Tracker
AI-assessed
Source 2 (PreventionWeb) and Source 3 (TIME) both confirm 'people with schizophrenia had 3 times higher odds of dying during the heat event compared with more typical summer weather.'
Source 1 (Living With Schizophrenia UK) and Source 5 (BC Medical Journal) both confirm '8% of those who died during the heat wave had a history of schizophrenia: up from 2.7%' and '1% of the BC population' representation.
Source 6 (Antipsychotics and other risk factors) states: 'during the 2018 event in Montreal, Canada, 25% of decedents had schizophrenic disorders despite a 0.6% prevalence of these conditions in the underlying population.'
Source 5 (BC Medical Journal) explicitly states: 'during that period schizophrenia was associated with a higher risk of death than any other chronic disease.'
Source 6 (Antipsychotics and other risk factors) confirms: 'the rate of death among those with schizophrenia and related illnesses doubled during heat wave periods from 1993 to 2006 in Adelaide, Australia.'
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