Heat Stress in Individuals With Schizophrenia

Impact of Indoor Overheating on Physiological Strain in Individuals With Schizophrenia

Schizophrenia is a severe mental illness affecting approximately 24 million people worldwide and is associated with more than double the all cause mortality risk of the general population. Emerging evidence demonstrates that elevated temperatures acutely worsen mental health symptoms and significantly increase the risk of heat related morbidity and mortality. For people living with schizophrenia, prolonged exposure to heat can exacerbate psychiatric symptoms, impair judgment and decision making, and reduce the ability to engage in protective behaviors such as increasing hydration, reducing clothing, improving ventilation, or seeking cooler environments. As a result, individuals with schizophrenia may experience higher rates of heat related illness. To date our understanding of heat exposure effects in individuals with schizophrenia remains incomplete, hindering the development of evidence-based strategies to protect them.

Thus, the primary objective of this exploratory study is to gather preliminary data on the effects of indoor overheating on physiological responses (core body temperature and cardiovascular function), cognitive performance (attention, working memory, and reaction time), and mood in adults with schizophrenia. Specifically, we will assess whether maintaining indoor conditions at the upper recommended temperature limit for older adults (26°C, 45% relative humidity [RH]; PMID: 38329752) is sufficient to mitigate physiological strain compared with exposure to a hot indoor environment (36°C, 45% RH) representative of non-air-conditioned homes during extreme heat events in individuals with schizophrenia. In both conditions, the individual will remain seated at rest while wearing light clothing (t shirt and shorts), with the exception of performing 15 minutes of stepping exercise (4-4.5 METS) each hour (excluding the lunch period) to reflect typical daily activities of daily living.

Study Overview

• Status: Recruiting
• Conditions: Cognitive Change; Physiological Stress; Heat Stress
• Intervention / Treatment: Other: Simulated exposure to indoor overheating

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Glen P Kenny, PhD; Phone Number: 4282 613-562-5800; Email: gkenny@uottawa.ca

Study Locations

• Canada
  • Ontario
    • Ottawa, Ontario, Canada, K1N 6N5
      • Recruiting
      • University of Ottawa
      • Contact: Glen P Kenny, PhD; Phone Number: 4282 613-562-5800; Email: gkenny@uottawa.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• English or French speaking.
• Ability to provide informed consent.
• Individuals with and without schizophrenia or schizoaffective disorder.

Exclusion Criteria:

• Endurance exercise training (greater than 3 sessions of vigorous exercise training per week for 30 minutes or more)
• Restrictions to physical activity
• Any history of diagnoses for other psychiatric disorders deemed to make participation in the study inadvisable.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Exposure to indoor temperature upper limit of 26°C; Participants exposed daylong (6 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29).	Other: Simulated exposure to indoor overheating; Individuals with schizophrenia exposed to a 6-hour simulated heat exposure
Experimental: Exposure to hot indoor environment of 36°C; Participants exposed daylong (6 hours) to an indoor temperature maintained at 36°C and 45% relative humidity (humidex equivalent of 45).	Other: Simulated exposure to indoor overheating; Individuals with schizophrenia exposed to a 6-hour simulated heat exposure

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Core temperature (Peak) during daylong exposure to indoor overheating	Peak core (indexed by visceral temperature) temperature (15 min average) during exposure. Visceral temperature is measured continuously throughout the 6 hour exposure to the simulated indoor overheating.	End of 6 hour daylong exposure

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean skin temperature (Peak) during daylong exposure to indoor overheating	Peak mean skin temperature (15 min average) during exposure. Mean skin temperature as calculated from skin temperature measured across 7 body regions is measured continuously throughout the 6 hour exposure to the simulated indoor overheating.	End of 6 hour daylong exposure
Mean skin temperature (AUC) during daylong exposure to indoor overheating	Areas under the curve (AUC) of mean skin temperature as calculated over 7 body regions during the 6 hour exposure to the simulate indoor overheating.	End of 6 hour daylong exposure
Mean skin temperature end of daylong exposure to indoor overheating	Mean skin temperature measured over 7 body regions at hour 6 of exposure to indoor overheating (15-min average).	End of 6 hour daylong exposure
Heat rate (Peak) during daylong exposure to indoor overheating	Peak heart rate (15 min average) during exposure. Heart rate is measured continuously throughout the 6 hour exposure to the simulated indoor overheating.	End of 6 hour daylong exposure
Heart rate (AUC) during daylong exposure to indoor overheating	Areas under the curve (AUC) of heart rate during the 6 hour exposure to the simulate indoor overheating.	End of 6 hour daylong exposure
Heart rate end of daylong exposure to indoor overheating	Heart rate measured at hour 6 of exposure to indoor overheating (15-min average).	End of 6 hour daylong exposure
Systolic blood pressure during daylong exposure to indoor overheating	Systolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures).	At the start (hour 0) and end of 6 hour daylong exposure
Diastolic blood pressure during daylong exposure to indoor overheating.	Diastolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures).	At the start (hour 0) and end of 6 hour daylong exposure
Reaction time during daylong exposure to indoor overheating (cognitive function).	Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of reaction time. Participants will be asked to initiate a movement of the device in response to a visual cue.	At the start (hour 0) and end of 6 hour daylong exposure
Impulse control during daylong exposure to indoor overheating (cognitive function).	Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of impulse control. Participants will be asked to respond to both "go" and "no-go" visual cues. In response to the "go" cue, participants will initiate a movement of the device.	At the start (hour 0) and end of 6 hour daylong exposure
Memory recall during daylong exposure to indoor overheating (cognitive function).	Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of memory recall. Participants complete both a delayed recall test and a working memory test.	At the start (hour 0) and end of 6 hour daylong exposure
CDC 4-Stage Balance Test during daylong exposure to indoor overheating (postural stability).	To assess postural stability, participants hold a tablet to their chest, then auditory cues guide participants through four consecutive stances, feet side by side, instep of one foot touching the big toe of the other foot, tandem stand with one foot in front of the other, heel touching toe, and stand on one foot. The balance assessment will be evaluated based on movement detected by an accelerometer integrated into the hardware of the tablet device (Sway Medical Inc).	At the start (hour 0) and end of 6 hour daylong exposure
Executive function during daylong exposure to indoor overheating (cognitive function).	Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of executive function. Participants will complete the Cued Stroop test, in which they are presented a sequence of congruent, neutral and incongruent color-word tasks.	At the start (hour 0) and end of 6 hour daylong exposure
BTrackS Balance Assessment during daylong exposure to indoor overheating (postural stability).	To assess postural stability, participants will be asked to stand on a BTracks force plate with their feet spread out to shoulder width, hand on their hips and eyes closed. The assessment will comprise of four trials (one practice trial) lasting 20 seconds in length and 20 seconds between trials. Center of pressure (COP) vector data along vertical (y) and horizontal (x) axes will be summed for the total path excursion length (cm) during each trial	At the start (hour 0) and end of 6 hour daylong exposure
Hydration status during daylong exposure to indoor overheating	Hydration status measured via assessing the urine specific gravity of a urine sample.	At the start (hour 0) and end of 6 hour daylong exposure
Fluid consumption during daylong exposure to indoor overheating	Average hourly fluid consumption calculated by weighing participant water intake at the start and end of each hour of exposure (normalized to the exposure duration).	At end of 6 hour daylong exposure
Fluid loss during daylong exposure to indoor overheating	Fluid loss calculated as the change in body mass during each exposure presented as a percentage of baseline body mass (corrected for food consumption).	At end of 6 hour daylong exposure
Core temperature (AUC) during daylong exposure to indoor overheating	Areas under the curve (AUC) of visceral temperature during the 6 hour exposure to the simulate indoor overheating.	End of 6 hour daylong exposure
Core temperature end of daylong exposure to indoor overheating	Visceral temperature measured at hour 6 of exposure to indoor overheating (15-min average).	End of 6 hour daylong exposure
Thermal sensation scale during daylong exposure to indoor overheating	Thermal sensation assessed via an ordinal scale (How hot do you feel?) ranging from "extremely hot" to "neutral".	At the start (hour 0) and end of 6 hour daylong exposure
Thermal sensation 2 scale during daylong exposure to indoor overheating	Thermal sensation assessed via an ordinal scale ("How do you feel?") ranging from "hot" to "cold" (midpoint: neutral)	At the start (hour 0) and end of 6 hour daylong exposure
Thermal comfort scale during daylong exposure to indoor overheating	Thermal comfort assessed via an ordinal scale ("How comfortable does your body temperature feel?") ranging from "very uncomfortable" to "comfortable".	At the start (hour 0) and end of 6 hour daylong exposure
Thirst sensation scale during daylong exposure to indoor overheating	Thirst sensation assessed via an ordinal scale ranging from very, very thirsty to not thirsty at all.	At the start (hour 0) and end of 6 hour daylong exposure
Feel good scale during daylong exposure to indoor overheating	Feel good scale assessed via an ordinal scale (How good do you feel?) ranging from "very good" to "very bad" (midpoint: neutral)	At the start (hour 0) and end of 6 hour daylong exposure
Activity levels (total steps taken) during daylong exposure to indoor overheating	Activity levels, quantified by number of steps taken per hour and totaled for each 6 hour exposure, assessed via a wearable accelerometer worn on the wrist and hip.	End of 6 hour daylong exposure
Perceived exertion scale during daylong exposure to indoor temperature limit.	Perceived exertional assessed via an ordinal scale ("How hard are you working?") ranging from "no exertional at all" to "maximal exertion"	At the start (hour 0) and end of 6 hour daylong exposure
Profiles of Mood States (POMS) during daylong exposure to indoor overheating	Potential changes in mood (7 subscales of mood: tension, anger, depression, fatigue, confusion, vigor and esteem related affect). The POMS-40 is a validated, self-administered questionnaire that examines seven distinct aspects of mood state across two positive subscales (Esteem-Related Affect, and Vigor) and five negative subscales (Fatigue, Tension, Confusion, Anger, and Depression), which are described across 40 distinct adjectives. For each individual item, participants are asked to describe "how you feel right now" by responding using a 5-point Likert scale (0 = "Not at all", 1 = "A little", 2 = "Moderately", 3 = "Quite a lot", or 4 = "Extremely"). The values of items associated with a specific subscale (e.g., Fatigue) are summed to calculate its score.	At the start (hour 0) and end of 6 hour daylong exposure
Environmental Symptoms Questionnaire (ESQ) during daylong exposure to indoor overheating	Self-reported environmental reactions and medical symptomatology associated with prolonged heat exposure. The ESQ-IV is a validated 68-item, self-administered questionnaire that has been used successfully in identifying symptomatology during exposure to a wide variety of environmental conditions, including heat exposure. Participants are asked to assess and described "how you have been feeling today" by responding to each item using a 6-point Likert scale (0 = "Not at all", 1 = "Slight", 2 = "Somewhat", 3 = "Moderate", 4 = "Quite a bit", or 5 = "Extreme"). Total Symptom Score is calculated from this data by taking the sum of the intensity ratings from all 68 individual items using reverse scores for the three positive items from the list ("I Felt Good", "I Felt Alert", and "I Felt Wide Awake").	At the start (hour 0) and end of 6 hour daylong exposure

Collaborators and Investigators

• Sponsor: University of Ottawa
• Investigators: Principal Investigator: Glen P Kenny, PhD, University of Ottawa

Study record dates

Study Major Dates

• Study Start (Actual): November 8, 2025
• Primary Completion (Estimated): May 31, 2027
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: January 20, 2026
• First Submitted That Met QC Criteria: January 28, 2026
• First Posted (Actual): February 3, 2026

Study Record Updates

• Last Update Posted (Actual): April 23, 2026
• Last Update Submitted That Met QC Criteria: April 20, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Schizophrenia; Physical activity; Thermoregulation; Mental health; Hyperthermia; Heat wave; Heat strain; Thermal comfort; Indoor temperatures; Indoor overheating; Heat vulnerability
• Additional Relevant MeSH Terms: Schizophrenia Spectrum and Other Psychotic Disorders; Mental Disorders; Wounds and Injuries; Body Temperature Changes; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Personal Satisfaction; Hyperthermia; Schizophrenia; Heat Stress Disorders; Psychological Well-Being; Motor Activity
• Other Study ID Numbers: HEPRU-2026-01-A

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No