Is the serious ambient air pollution associated with increased admissions for schizophrenia?

Background: Much of the research has shown an increased risk of psychiatric disorders in association with elevated exposure to air pollution, such as NO₂, PM₁₀ and SO₂. However, few studies investigate the effect of these air pollution on the risk of schizophrenia admissions and the lagged effect among different subgroups.

Methods: A distributed lag non-linear model (DLNM) combined with a Poisson generalized linear regression model was applied to analyzing the relationship between schizophrenia and air pollution. At first, according to the minimum AIC criterion, we discussed the lagged effect of NO₂, PM₁₀ and SO₂ for 5 days, 4 days and 10 days, respectively. Then, we chose benchmarks as references (25th) to conduct comparisons with different levels of pollutant concentrations (90th and 95th). All patients were retrieved from the Psychiatric Hospital of TongLing (n = 3469) from January 2014 to December 2016. Daily air pollutants and meteorological data were collected from the Chinese national air quality monitoring (NAQM) and Meteorological Bureau. Subgroup analysis was conducted by gender (male and female), age (0-19 ages, 20-39 ages, 40-59 ages and ≥ 60 ages) and occupation (farmer, worker and unemployed).

Results: The effects of the three air pollutants were statistically significant to schizophrenia admissions. We found that NO₂ and PM₁₀ have short-term effects of 4 days and 3 days (NO₂: lag 0-4 RR, 1.84(95% CI: 1.49-2.27), PM₁₀: lag 0-3 RR, 1.97(95%CI: 1.57-2.36)), respectively. SO₂ had longer effects for 10 days (SO₂: lag 0-10 RR, 2.93(95%CI: 2.10-4.10)). Additionally, it significantly increased the risk of schizophrenia episode in subjects with male, 20-59 ages, farmer and worker.

Conclusion: We find adverse effects of ambient air pollutants on schizophrenia admissions in TongLing, China, which may provide valuable information for the policy makers and local health authorities to conduct effective intervention of air pollution on schizophrenia.