The relationship between fine particulate matter (PM2.5) and schizophrenia severity

Rika Eguchi, Daisuke Onozuka, Kouji Ikeda, Kenji Kuroda, Ichiro Ieiri, Akihito Hagihara

Although particulate matter (PM) is reported to affect the rate of emergency admissions for schizophrenia, no study has examined the relationship between particulate matter less than 2.5 μm in diameter (PM2.5) and the severity of schizophrenia. We obtained data on patients with schizophrenia at a psychiatric hospital, and on air pollution in Sakai, Japan between Feb 1, 2013 and April 30, 2016. Multivariate logistic regression analyses were used to estimate the relationship between PM2.5 concentrations and scores on the Brief Psychiatric Rating Scale (BPRS) of schizophrenia patients at admission, with a lag of up to 7 days. During the study period, there were 1193 schizophrenia cases. The odds ratio (OR) for a BPRS score ≥ 50 at admission was 1.05 [95% confidence interval 1.00-1.10] and the effect of PM2.5 concentration was significant for lag period of 2 days. The ORs associated with PM2.5 concentration increased substantially for patients over 65 years of age. Ambient PM2.5 concentration was associated with exacerbation of schizophrenia. Our results suggest that protection for several days should be considered for controlling PM2.5-related schizophrenia, especially among elderly patients.