Long-term air pollution exposure and incidence of mental health conditions: evidence from an Italian cohort of young adults.

BACKGROUND

Ambient air pollution is a ubiquitous risk factor with adverse health effects. Its association with the incidence of mental disorders among young adults is still unclear. We aim to estimate the association between ambient air pollution and the incidence of mental disorders, or first use of psychotropic drugs, among a cohort of young adults residing in Rome, Italy.

METHODS

We followed-up a population-based cohort of individuals aged 15-25 years and evaluated the association between long-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2) and black carbon (BC), estimated at 100 m spatial resolution, and the onset of mental disorders. We used primary discharges of hospital admissions to identify incident cases of schizophrenia, depression, anxiety and eating disorders, or first prescription of antipsychotics or antidepressants.

RESULTS

The cohort included ∼230,000 individuals free of mental disorders (or use of psychotropic drugs) at baseline. Incident rates (per 10,000 person-years) ranged between 3.7 for schizophrenia and 1.0 for eating disorders; higher rates were observed for the two outcomes based on drug prescription. Higher exposure to PM2.5 was significantly associated with schizophrenia: each 1.1 μg/m3 increment of the pollutant increased the risk of the disease by 15% (95% confidence interval [95%CI]: 3%; 28%). All three pollutants were associated with drug use: for example, each 8.0 μg/m3 increment of NO2 increased the risk of first use of antipsychotics by 7% (95%CI: 1%; 13%) and antidepressants by 4% (95%CI: 0%; 7%).

CONCLUSIONS

These results show that ambient air pollution is associated with incidence of mental disorders.