Extreme Ambient Temperature and Differential Risk of Mental Disorder-Related Emergency Department Visit by Disorder, Sex and Age: A Case-Time Series Analysis in Korea

Background:The impacts of extreme ambient temperatures on mental health may vary by type of disorders, age and sex.We examined the association between extreme ambient temperatures and emergency department (ED) visits for prevalent mental disorders, stratified by age and sex.Methods: We analyzed the National Emergency Department Information System data in 2015-2021, Korea.Using a case-time series design, we calculated relative risks (RRs) of ED visits for prevalent mental disorders at extremely high (97.5thpercentile) and low (2.5th) ambient temperatures, stratified by age (0-19, 20-39, 40-64, and 65) and sex.A lag period of 0-5 days was considered for ambient temperature and air pollution.Results: Of 1,351,463 ED visits due to mental disorders, neurotic, stress-related and somatoform disorder (anxiety disorder, 31.5%),organic mental disorder (OMD, 25.2%), substance use disorder (SUD, 24.5%) and mood disorder (MD, 15.2%) were common.At extreme high temperatures, the RR of anxiety-related visits was 2.25 (95% confidence interval [CI], 1.87-2.71),with men 20-39 years at higher risk (4.02; 95% CI, 2.77-5.85)than women (1.65; 95% CI, 1.17-2.32,P for difference < 0.001), versus minimum-risk ambient temperature.Extreme heat also raised RR for OMD in men 40-64 years (1.49; 95% CI, 1.01-2.21),SUD in women 20-39 years (2.72; 95% CI, 1.85-3.99)and MD in women 65 years (2.00; 95% CI, 1.42-2.80).Risk estimates at extreme low temperatures were generally imprecise, except for anxiety in men 20-64 years.These associations were not replicated among children and adolescents (0-19 years).Conclusion: Our findings emphasize the need for more tailored climate change adaptation strategies considering the varying vulnerabilities of populations to mental disorders.