Assessing the impact of heatwaves on emergency visits for major depression and suicidal ideation in youth with attention-deficit/hyperactivity disorder

Emerging evidence suggests that extreme heat can exacerbate mental health conditions. Yet little is known about its impact on children with attention-deficit/hyperactivity disorder (ADHD), a population at increased risk for emotional dysregulation and impulsivity. This study examines the association between heatwave exposure and emergency department visits for major depressive disorder (MDD), suicidal behavior (SUIC), and their co-occurrence among youth with ADHD. We conducted a retrospective matched-case study of 4,404 pediatric ED visits for MDD and/or SUIC in youth with ADHD in North Carolina from May to September, 2008-2021. Heatwave exposure was defined using the Excess Heat Factor and modeled as same-day, lagged (1-7 days), and cumulative (3-,5-, and 7-day) periods. Poisson mixed-effect regression models estimated relative risk (RR) and 95% confidence intervals (CI). Intersectional models further explored how risk varied by race, sex, ethnicity, and ADHD subtype. Heatwave exposure was significantly associated with increased ED visits for MDD (RR = 1.17, 95%CI: 1.01, 1.34) on the same day and overlapping MDD and SUIC (RR = 1.30, 95%CI: 1.02-1.65) on lag day one. Adolescents aged 12-17 showed heightened vulnerability across all outcomes. Cumulative exposure over 3-, 5-, and 7-day periods further elevated risks for MDD and suicidal behavior. Youth with the inattentive ADHD subtype had significantly greater odds of experiencing an overlapping MDD-suicidal event following heatwave exposure (RR = 2.70, 95%CI: 1.35-5.38). Intersectional analyses revealed that white females had the highest risk for suicide-related ED visits (RR = 1.21, 95%CI: 1.04-1.41). This study is the first to identify a link between heatwave exposure and mental health crises in youth with ADHD, emphasizing the need for targeted interventions. Findings highlight the importance of integrating climate resilience strategies into pediatric mental health care, particularly for high-risk subgroups.