Temperature Exposure and Psychiatric Symptoms in Adolescents From 2 European Birth Cohorts

Abstract

Importance: Climate change can adversely affect mental health, but the association of ambient temperature with psychiatric symptoms remains poorly understood.

Objective: To assess the association of ambient temperature exposure with internalizing, externalizing, and attention problems in adolescents from 2 population-based birth cohorts in Europe.

Design, setting, and participants: This cohort study analyzed data from the Dutch Generation R Study and the Spanish INMA (Infancia y Medio Ambiente) Project. Generation R recruited 9898 women during pregnancy or shortly after birth, with children born between 2002 and 2006. INMA recruited 2270 pregnant women from Gipuzkoa, Sabadell, and Valencia, Spain, with children born between 2003 and 2008. Individuals born from live singleton births with available outcome and exposure data were included in the study. Data were analyzed between October 2023 and November 2024.

Exposure: Daily ambient temperature 2 weeks, 1 month, and 2 months preceding outcome assessment was calculated between December 2015 and November 2022 at the residence at 100 × 100 m resolution utilizing the UrbClim model.

Main outcomes and measures: The primary outcomes were internalizing, externalizing, and attention problems, measured with the maternal-reported Child Behavioral Checklist for ages 6 to 18 years; raw scores were square-root transformed, with higher scores indicating more problems. Distributed lag nonlinear models evaluated the associations of temperature exposure with problem scores in each country and region. For Spain, results from the 3 INMA regions were combined using random-effects meta-analysis. Results show the accumulated temperature association over each exposure period.

Results: A total of 3934 participants from Generation R (mean [SD] age at assessment, 13.6 [0.4] years; 1971 female [50%]) and 885 from INMA (mean [SD] age at assessment, 14.9 [1.0] years; 458 female [52%]) were included. Most parents in both cohorts were native to the respective countries of each cohort and had relatively high socioeconomic status. Daily temperatures ranged from -5.2 °C to 32.6 °C in the Netherlands and 3.3 °C to 33.9 °C in Spain. In Generation R, the mean (SD) square-root transformed scores were 2.0 (1.2) for internalizing problems, 1.6 (1.3) for externalizing problems, and 1.5 (1.0) for attention problems, while in INMA these were 2.4 (1.2), 2.1 (1.3), and 1.5 (1.1), respectively. In the Netherlands, cumulative exposure to cold was associated with more internalizing problems (eg, 0.76 [95% CI, 0.20-1.32] higher square-root points at 5.5 °C exposure over a 2-month exposure). In Spain, cumulative exposure to heat was associated with more attention problems (eg, 1.52 [95% CI, 0.39-2.66] higher square-root points at 21.7 °C exposure over a 2-month exposure).

Conclusions and relevance: In this cohort study, exposure to cold in the Netherlands and heat in Spain were associated with more psychiatric symptoms, highlighting distinct temperature exposure and mental health associations among adolescents. Future studies should explore this across diverse climates to further quantify the intricate and multifactorial association of climate change with mental health.

Figure 1.. Daily Temperature in 2 European Birth Cohort Populations During the 2 Months Before Outcome Assessment

The month and year at the top of the plot indicate the first and last months of Child Behavioral Checklist for ages 6 to 18 years assessment within each cohort or region. Gipuzkoa, Sabadell, and Valencia comprise the Spanish INMA (Infancia y Medio Ambiente) Project.

Figure 2.. Cumulative Associations of Temperature Exposure Before Outcome Assessment With Psychiatric Symptoms in Adolescents From the Generation R Study

The x-axis depicts the 5th to 95th percentile range of the country-wide temperature distribution (2.3°C to 22.8 °C for the 2-week lag period, 2.5°C to 22.7 °C for the 1-month lag period, and 2.7 °C to 22.8 °C for the 2-month lag period). Solid dark blue lines represent the country-average curve, expressed as β coefficients of the problem scores, derived from the distributed lag nonlinear models, with their respective 95% CIs shaded in light blue; the dark blue dot and light blue dotted line in each plot represents the reference temperature. Coefficients are estimated as the change in the square-root transformed outcome score at each temperature of the country-wide temperature distribution respective to the corresponding reference temperature. Light beige (colder compared with reference temperature) shaded areas indicate the range of statistically significant associations at the P < .05 level and dark beige shaded areas indicate statistically significant associations after correction for multiple testing (P < .025).

Figure 3.. Cumulative Associations of Temperature Exposure Before Outcome Assessment With Psychiatric Symptoms in Adolescents From the INMA (Infancia y Medio Ambiente) Project

The x-axis depicts the 5th to 95th percentile range of the country-wide temperature distribution (8.9 °C to 25.0 °C for the 2-week lag period, 8.5 °C to 24.5 °C for the 1-month lag period, and 8.0 °C to 24.3 °C for the 2-month lag period). Solid dark blue lines represent the country-average curve, expressed as β coefficients of the problem scores, derived from the random-effects meta-analysis models, with their respective 95% CIs shaded in light blue; the dark blue dot and light blue dotted line in each plot represents the reference temperature. Coefficients are estimated as the change in the square-root transformed outcome score at each temperature of the country-wide temperature distribution respective to the corresponding reference temperature. Light beige (warmer compared with reference temperature) shaded areas indicate the range of statistically significant associations at the P < .05 level and dark beige shaded areas indicate statistically significant associations after correction for multiple testing (P < .025).