Importance: Air pollution exposure damages the brain, but its associations with the development of psychopathology are not fully characterized.
Objective: To assess whether air pollution exposure in childhood and adolescence is associated with greater psychopathology at 18 years of age.
Design, Setting, and Participants: The Environmental-Risk Longitudinal Twin Study is a population-based cohort study of 2232 children born from January 1, 1994, to December 4, 1995, across England and Wales and followed up to 18 years of age. Pollution data generation was completed on April 22, 2020; data were analyzed from April 27 to July 31, 2020.
Exposures: High-resolution annualized estimates of outdoor nitrogen oxides (NOx) and particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) linked to home addresses at the ages of 10 and 18 years and then averaged.
Main Outcomes and Measures: Mental health disorder symptoms assessed through structured interview at 18 years of age and transformed through confirmatory factor analysis into continuous measures of general psychopathology (primary outcome) and internalizing, externalizing, and thought disorder symptoms (secondary outcomes) standardized to a mean (SD) of 100 (15). Hypotheses were formulated after data collection, and analyses were preregistered.
Results: A total of 2039 participants (1070 [52.5%] female) had full data available. After adjustment for family and individual factors, each interquartile range increment increase in NOx exposure was associated with a 1.40-point increase (95% CI, 0.41-2.38; P = .005) in general psychopathology. There was no association between continuously measured PM2.5 and general psychopathology (b = 0.45; 95% CI, -0.26 to 1.11; P = .22); however, those in the highest quartile of PM2.5 exposure scored 2.04 points higher (95% CI, 0.36-3.72; P = .02) than those in the bottom 3 quartiles. Copollutant models, including both NOx and PM2.5, implicated NOx alone in these significant findings. NOx exposure was associated with all secondary outcomes, although associations were weakest for internalizing (adjusted b = 1.07; 95% CI, 0.10-2.04; P = .03), medium for externalizing (adjusted b = 1.42; 95% CI, 0.53-2.31; P = .002), and strongest for thought disorder symptoms (adjusted b = 1.54; 95% CI, 0.50-2.57; P = .004). Despite NOx concentrations being highest in neighborhoods with worse physical, social, and economic conditions, adjusting estimates for neighborhood characteristics did not change the results.
Conclusions and Relevance: Youths exposed to higher levels of outdoor NOx experienced greater psychopathology at the transition to adulthood. Air pollution may be a nonspecific risk factor for the development of psychopathology.
Bibliographical noteFunding Information:
Administrative, technical, or material support: Arseneault, Beddows, Beevers, Ambler, Odgers. Supervision: Fisher. Conflict of Interest Disclosures: Dr Newbury reported receiving grants from Wellcome Trust and the British Academy during the conduct of the study. Dr Fisher reported receiving grants from the Natural Environment Research Council (NERC)–Medical Research Council (MRC)–Chief Scientist Office (CSO), Wellcome Trust, and Economic and Social Research Council (ESRC) during the conduct of the study. No other disclosures were reported.
Funding/Support: The Environmental-Risk (E-Risk) Longitudinal Twin Study is funded by grant G1002190 from the MRC. Additional support was provided by grant HD077482 from the US National Institute of Child Health and Human Development, Google, the Jacobs Foundation, joint grant NE/P010687/1 from NERC-MRC-CSO, and grant 204823/Z/16/Z from the King’s Together Multi and Interdisciplinary Research Scheme (Wellcome Trust Institutional Strategic Support Fund). Mr Reuben was supported by grant F31ES029358 from the US National Institute of Environmental Health Sciences. Professor Odgers was supported by fellowships from the Jacobs Foundation and the Canadian Institute for Advanced Research. Professor Arseneault is the Mental Health Leadership Fellow for the ESRC. Dr Fisher was supported by grant ES/S012567/1 from the ESRC to the Centre for Society and Mental Health at King’s College London. Dr Newbury was supported by Sir Henry Wellcome Postdoctoral Fellowship 218632/Z/19/Z from the Wellcome Trust. Dr Schaefer was supported by T32 Postdoctoral Fellowship T32MH015755 from the US National Institute of Mental Health.
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