Association Between Extreme Heat and Externalizing Symptoms in Pre- and Early Adolescence: Findings From the ABCD Study

Objective

Considering the growing threat of climate change and the current youth mental health crisis, data are needed on the relationship between climate and youth mental health. Hot weather contributes to the mental health burden, specifically aggression. We studied associations between extreme heat and externalizing symptoms or suicidal behavior among US preadolescents.

Method

We analyzed data from the Adolescent Brain Cognitive Development (ABCD) Study. Participants (N = 8,120, mean age 9.89 years at baseline, 48.40% female, 23.81% Black, 18.17% Hispanic) were assessed longitudinally between 2016 and 2020 across 21 sites. We estimated exposure to extreme heat (measured around the study site) as the number of days in the month of study visit with a maximum temperature ≥90°F (32.2°C) based on National Centers for Environmental Information data. We characterized exposure to extreme heat across racial/ethnic groups. We used mixed-effects regression models to test associations of extreme heat with externalizing symptoms (parent-report) and suicide attempts (self-report), assessed in a validated clinical interview. Models adjusted for demographics (age, sex, race, ethnicity, and household income) and neighborhood characteristics (gross residential density, population density, national walkability index, and fraction of grass, forest, and built land use).

Results

Exposure to extreme heat was less prevalent among non-Hispanic White participants (5.2 days/mo) compared to non-Hispanic Black and to Hispanic youth (7.2 and 7.4 days/mo, respectively). Extreme heat showed a small but significant association with externalizing symptoms (incidence rate ratio [IRR]=1.06, 95% CI = 1.04-1.08, p < .001). The association did not change when adjusting for demographics, and remained similar when further adjusting for neighborhood characteristics (IRR = 1.05, 95% CI = 1.00-1.12, p = .04). Sensitivity analyses using extreme heat at the participants’ home address level in the 6 days prior to study visit, available only for ABCD baseline assessment, revealed similar findings. Extreme heat was not associated with suicide attempts (odds ratio = 0.94, 95% CI = 0.77-1.14, p = .52).

Conclusion

Our findings add to the literature on the association between extreme heat and externalizing symptoms, and suggest that this association already exists in preadolescence. Future studies are warranted to better understand the mechanisms linking hot weather and mental health and its related racial/ethnic disparities.

Plain language summary

Using data from the ABCD Study that follows 8,120 children from childhood to adolescence, this study found an association of exposure to extreme heat, defined by days of the month with ≥ 90°F (32.2°C), with behavioral symptoms in preadolescents aged 10-12 years across the US. In addition, the study found that youth of color are exposed to more extreme heat, which might contribute to youth mental health disparities. While the association observed between heat and behavioral problems was small in magnitude, this large-scale study adds to the evidence of the negative contribution of climate change to youth mental health in the US. More research is needed to uncover mechanisms that explain how climate change affects the mental health of young people and its related disparities.

Study preregistration information

Association between extreme heat and mental health in early adolescence; https://osf.io/ph7y2/.

Diversity & Inclusion Statement

We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. We actively worked to promote sex and gender balance in our author group.

We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. While citing references scientifically relevant for this work, we also actively worked to promote sex and gender balance in our reference list.