Is short-term exposure to heat associated with anxiety and depression? A case-crossover analysis

Background: Health impacts of heat are increasingly important due to climate change. Anxiety and depression are common and understudied mental health conditions, which may be associated with heat exposure. We examined associations between short-term (5-day) mean apparent temperature and health visits for anxiety or depression in North Carolina in a case-crossover analysis of electronic health records. Methods: We identified 2256 adults with anxiety or depression in a random sample of electronic health records from University of North Carolina Healthcare System patients 2004-2018. We examined 5-day mean apparent temperature (incorporating temperature and humidity) at the ZIP code level for patients during 9177 visits with a diagnosis of anxiety or depression compared to control time points 14 and 28 days before and after each visit. We used conditional logistic regression models adjusted for personal (age, sex, race, health insurance status), environmental (season, annual PM2.5 concentration, climate division) and neighborhood (median household income, percent Bachelor degree or more, percent urban) factors. We conducted analyses overall and stratified by diagnosis, sex, and season. Results: Median age of patients was 46 years, 70% were female, and 75% were White. Mean 5-day apparent temperature was 18.5°C (SD 10.4). We did not observe an association between 5-day mean apparent temperature and anxiety or depression overall (OR 1.00, 95% CI 1.00-1.00). However, we observed positive associations between temperature and anxiety or depression during summer months (OR 1.09, 95% CI 1.07-1.11) and inverse associations in winter (OR 0.96, 95% CI 0.95-0.98). Conclusions: We did not observe associations between apparent temperature and anxiety or depression overall, but we observed season-specific associations. In hotter months, increased apparent temperature may be detrimental to mental health; in colder months, increased apparent temperature may be beneficial to mental health.

Impact/Purpose

Health impacts of heat are important and will continue to be important as the climate changes. Anxiety and depression are common mental health conditions that may be linked to environmental factors. We examined whether hospital visits with anxiety or depression are associated with mean five-day apparent temperature (incorporating temperature and humidity). The population for this study was 2256 adult patients over 9177 hospital visits in North Carolina. We compared apparent temperatures on the five days before their visit compared to 14 and 28 days before and 14 and 28 days after. Overall, we did not observe associations between anxiety and depression, but we saw higher temperatures associated with more hospital visits in the summer and fewer in the winter. This may indicate that high temperatures are associated with worse mental health in summer and better mental health in winter.

Citation

Weaver, A., C. Gray, E. Slawsky, J. Moyer, AND C. Ward-Caviness. Is short-term exposure to heat associated with anxiety and depression? A case-crossover analysis. Society for Epidemiologic Research 2023 Annual Meeting, Portland, OR, June 13 - 16, 2023.