Air pollution and adolescent psychosis

Relation

Newbury J, Arseneault L, Beevers S, et al. Association of air pollution exposure with psychotic experiences during adolescence [published online ahead of print March 27, 2019]. (Link removed).

Study objective

To evaluate the association between adolescent psychosis and air pollution and to further determine whether this may be an underlying etiology for increased rates of adolescent psychosis in urban housing.

Draft

Population-based cohort study from the United Kingdom Environmental-Risk Longitudinal Twin Study

Participant

The study included 2,232 adolescents who were followed from birth to age 18 as part of the Environmental-Risk Longitudinal Twin Study. Participants were born between 1 January 1994 and 4 December 1995 and were nationally representative of the geographical and socio-economic status of British families.

Of the original participants, 2,066 (92.6%) completed the 18-year follow-up; 2,063 of those followed up reported psychotic experiences. Of these, 52.5% of participants were female and 47.5% were male.

Study parameters assessed

Data collected included exposure to air pollution, urbanicity of participants, and occurrence of psychotic events between ages 12 and 18.

Participants were assessed first at age 5 and again at ages 7, 10, 12, and 18 years. During the final assessment at age 18, researchers conducted private interviews with each participant to assess the possible occurrence of 13 different psychotic experiences since age 12. Seven items related to delusions and hallucinations and 6 items related to prodromal psychosis experiences. Each experience was coded as present (2), probably present (1), or absent (0), then summed and presented on an ordinal scale and verified by healthcare professionals.

The implications of this study are important not only for practitioners treating adolescents but also for those primarily focused on adult health, as early psychotic episodes are a risk factor for adult psychosis and require early intervention.

Exposure to air pollution was measured using estimates of pollution generation from participants' home addresses and 2 frequently visited locations (often school, work, or stores) in 2012, 1 year before interviews with participants began. The pollutants measured included nitrogen dioxide (NO₂), nitrogen oxides (NO_X) and particulate matter (PM_2.5and PM₁₀) from inorganic aerosols, carbon-containing aerosols and dusts. The measurements were carried out using high-resolution estimates from the Community Multiscale Air Quality (CMAQ-urban) Modeling System. Air pollution exposure was estimated by calculating average pollutant levels at each participant's three most frequently visited locations.

Urbanicity scores were derived from 2011 census data; Thirty-two percent of participants with available data lived in urban environments at age 18.

Analyzes controlled for covariates that could confound the data, including the following: family or neighborhood socioeconomic status; maternal or other family history of psychosis; psychotic episodes in childhood; smoking or drug abuse; and neighborhood crime or social conditions.

Primary outcome measures

The primary outcome was the number of psychotic events occurring between the ages of 12 and 18 years.

Key insights

Six hundred twenty-three (30.2%) participants experienced at least 1 psychotic episode between the ages of 12 and 18 years, ranging from mild paranoia to severe psychotic symptoms.

• 1.440 (69,8 %) berichteten über keine psychotischen Erfahrungen
• 319 (15,5 %) berichteten von 1-2 Erfahrungen
• 155 (8%) berichteten von 3-5 Erfahrungen
• 138 (6,7 %) erlebten 6 oder mehr Episoden

In terms of air quality, those with the highest NO exposure were adolescents (top quartile of participants' total exposure).₂NO_Xand particulate matter reported more psychotic experiences than those consistently exposed to better air quality.

Higher NO levels₂NO_XPM_2.5and PM₁₀were strongly associated with urban areas. In fact, intermediate levels of NO_xand PM_2.5In urban areas, permissible levels were found to be exceeded according to World Health Organization (WHO) guidelines.

Specific pollutants have also been examined for their independent association with adolescent psychosis, and pathways mediating NO have been found₂and no_Xaccounted for 55% and 58% of the association of urban-dwelling adolescents and psychotic episodes, respectively. In combination NO₂and no_Xaccounted for 60% of psychotic experiences among urban adolescents.

There was no evidence that frequency of occurrence was associated with other potentially confounding factors (e.g., socioeconomic status, family history, substance abuse).

Practice implications

The data from this study are important not only for practitioners who treat adolescents but also for those who primarily focus on adult health, as early psychotic episodes are a risk factor for psychosis in adulthood and require early intervention.¹While there is data that the prevalence of psychotic episodes is higher among adolescents growing up in cities,²and other studies have linked air pollution to a variety of mental health problems,^3.4Few have considered how these two variables interact to influence our youth.

As cities become increasingly congested, we are likely to see higher levels of air pollutants from vehicles, industry and general domestic use of exhaust products. As a result, practitioners may also experience higher rates of mental illness (not to mention increased heart and respiratory problems^5.6) in both adolescents and adults. Many studies suggest that the adolescent brain is more vulnerable to environmental damage.⁷For this reason, we should extend our most comprehensive neurological assessments to our adolescent populations.