Ambient temperature and emergency department visits for mental disorder before and during the COVID-19 pandemic

Ambient temperature and the COVID-19 pandemic have both been increasingly associated with mental health issues in many regions of the world, but little is known about the potential role of this pandemic in modifying the association between increased temperature and effects on mental health disorders. We analyzed and compared the associations of mental health disorders (schizophrenia, depression, anxiety, and bipolar disorder) with short-term temperature changes (daily mean temperature and diurnal temperature range) before and during the COVID-19 pandemic in an eastern Chinese city (Hefei). Mean temperature rise (per 1 °C increase) and high diurnal temperature range (99th percentile compared with risk-surge point of diurnal temperature range) were associated with increased risk of emergency department visits for schizophrenia and depression. The effect of mean temperature and diurnal temperature range on depression-related visits was significantly greater during the pandemic than before, whereas there were no significant differences in the effects of temperature changes on emergency department visits for other mental health disorders between the pre-pandemic and pandemic periods. This study provides additional evidence that the COVID-19 pandemic may have modified the effects of short-term temperature changes on mental health disorders, especially depression.