Long-term particulate matter exposure and onset of depression in middle-aged men and women

BACKGROUND: Long-term exposure to particulate matter (PM) air pollution is associated with all-cause mortality and adverse cognitive outcomes, but the association with developing depression remains inconsistent. OBJECTIVE: Our goal was to evaluate the prospective association between PM air pollution and developing depression assessed using the Center for Epidemiological Studies Depression (CES-D) scale. METHODS: Subjects were drawn from a prospective cohort study of 123,045 men and women free of depressive symptoms at baseline who attended regular screening exams in Seoul and Suwon, South Korea, from 2011 to 2015. Exposure to PM with an aerodynamic diameter of <10 and <2:5 lm (PM₁₀ and PM_2/5, respectively) was estimated using a land-use regression model based on each subject’s residential postal code. Incident depression was defined as a CES-D score >16 during follow-up. As a sensitivity analyses, we defined incident depression using self-reports of doctor’s diagnoses or use of antidepressant medications during follow-up. RESULTS: The mean baseline 12-month concentrations of PM₁₀ and PM_2/5 were 50.6 (4.5) and 24:3 ð1:3Þ lg=m³, respectively. The hazard ratios (HRs) and 95% confidence intervals (CIs) for developing depression associated with a 10-lg=m³ increase in 12-and 60-month PM₁₀ exposure were 1.11 (95% CI: 1.06, 1.16) and 1.06 (95% CI: 1.01, 1.11), respectively. The corresponding HRs for 12-month PM_2/5 exposure was 0.96 (95% CI: 0.64, 1.43). Similar results were obtained when incident depression was identified using self-reports of doctor’s diagnoses or the use of antidepressant medications. CONCLUSION: In this large cohort study, we found a positive association between long-term exposure to outdoor PM₁₀ air pollution and the developing depression. We did not find an association for outdoor PM_2/5 air pollution; however, we had a much shorter follow-up for subjects’ exposure to PM_2/5.