Importance: Urbanicity is a well-established risk factor for both clinical (e.g., schizophrenia) and subclinical (e.g., hearing voices and paranoia) expressions of psychosis. No studies have examined the association of air pollution with adolescent psychotic experiences, despite air pollution being a major toxic exposure in cities.

Objective: To examine the association between air pollution and adolescent psychotic experiences, and test whether air pollution mediates the association between urban residency and adolescent psychotic experiences.

Design: The Environmental-Risk (E-Risk) Longitudinal Twin Study, a longitudinal cohort study of 2,232 children born in 1994-1995 in England and Wales and followed from birth to age 18.
Setting: This population-based cohort represents the geographic and socioeconomic composition of UK households.

Participants: 93% (N=2066) of the original cohort participated in assessments at age 18, of whom 99.9% (N=2063) provided data on psychotic experiences.

Exposures: High resolution annualized estimates of four air pollutants – nitrogen dioxide (NO2), nitrogen oxides (NOx) and particulate matter (PM2.5 and PM10) – were modelled for 2012 and linked to the home addresses of the sample plus two commonly visited locations when the participants were aged 18.

Main outcome(s) and measure(s): At age 18, participants were privately interviewed regarding adolescent psychotic experiences. Urbanicity was estimated using 2011 census data.
Results: Sex was evenly distributed (51% female). 30.2% (N=623/2063) of participants had at least one psychotic experience between ages 12 and 18. Psychotic experiences were significantly more common among adolescents with the highest (top quartile) annual exposure to NO2 (OR, 1.71; 95% CI, 1.28-2.28), NOx (OR, 1.72; 95% CI, 1.30-2.29), and PM2.5 (OR, 1.45; 95% CI, 1.11-1.90). NO2 and NOx together statistically explained 60% of the association between urbanicity and adolescent psychotic experiences. There was no evidence of confounding by family socioeconomic status (SES), family psychiatric history, maternal psychosis, childhood psychotic symptoms, adolescent smoking and substance dependence, or neighborhood SES, crime and social conditions.

Conclusions and relevance: Air pollution exposure – particularly NO2 and NOx – was associated with increased odds of adolescent psychotic experiences, and this partly explained the association between urban residency and adolescent psychotic experiences. Both biological (e.g., neuroinflammation) and psychosocial (e.g., stress) mechanisms are plausible.
Original languageEnglish
Pages (from-to)614-623
Number of pages10
JournalJAMA Psychiatry
Issue number6
Early online date27 Mar 2019
Publication statusPublished - Jun 2019


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