Role of Temperature on Health Outcomes for People with Schizophrenia Spectrum Disorders

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2026-03-05

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Abstract

Rising ambient temperatures and more frequent temperature extremes are increasingly recognized as important determinants of health, particularly for people with schizophrenia spectrum disorders (SSD) who are vulnerable to heat- and cold-related risks. This thesis first reviews evidence on how ambient and extreme air temperatures are associated with SSD-related health outcomes. Extreme heat was consistently linked to higher risks of emergency department (ED) visits, hospitalizations, and mortality. A few studies also linked extreme cold with increased outpatient visits and hospital admissions. Ambient and diurnal temperature range effects were smaller and heterogeneous, and apparent and seasonal metrics suggested additional risks that vary by sociodemographic and regional factors. Next, we examined the short-term effects of extreme temperature on ED visits among people with SSD in Ontario, Canada, using a time-stratified case-crossover design with conditional Poisson and distributed lag non-linear regression models. Extreme heat was associated with a lower risk of mental health ED visits, but a higher risk of non-mental health ED visits. Extreme cold was associated with a lower risk of non-mental health ED visits and was not associated with mental health ED visits.

Summary for Lay Audience

As the climate warms and extreme temperatures become more common, research shows higher risks of death, heart and lung problems, and mental health crises, particularly in vulnerable groups. People with schizophrenia spectrum disorders (SSD) already face serious health challenges, including physical illnesses and difficulties regulating body temperature, which may make them especially sensitive to heat and cold. This work reviews existing studies on temperature and SSD, then focuses on how extreme temperatures are linked to emergency department (ED) use for both mental and physical health reasons among people with SSD in Ontario, Canada. I systematically reviewed all published studies that looked at how temperature affects the health of people with SSD. I searched three major medical databases, screened nearly 3,600 records, and ultimately included 37 studies from around the world. These studies used different ways of measuring temperature (for example, heat waves, cold spells, and day-to-day temperature changes) and examined outcomes such as emergency visits, hospital admissions, and deaths. Overall, the review found that extreme heat, and to a lesser extent extreme cold, were often linked to higher use of health services and poorer health outcomes for people with SSD. In the second part of the study, I used health records and weather data from across Ontario to see how very hot and very cold days affect ED visits among people with SSD. Each person was compared to themselves on different days, which helps separate the effect of temperature from their usual health service use patterns. The study included over 116,000 people with SSD and more than 160,000 ED visits in 2019 and separately looked at visits for mental health and non-mental health reasons. Daily temperature, air pollution, and humidity were linked to each person’s home address, and advanced statistical models were used to track how temperature affects ED visits over several days. The results show that extreme heat was followed by fewer ED visits for mental health reasons but more ED visits for non-mental health reasons. During periods of extreme cold, there were fewer ED visits for non-mental health reasons and no effect on ED visits for mental health reasons.

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Keywords

Schizophrenia spectrum disorders, extreme temperature, heat and cold exposure, climate-related health impacts, health service utilization, emergency department utilization, case-crossover design, distributed lag models.

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https://hdl.handle.net/20.500.14721/39515

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