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Background:The impact of air pollution and road traffic noise on depression remains inconclusive. This study examined long-term residential exposure to air pollutants and road traffic noise in relation to dispensed antidepressant medications.

Methods:A cohort study was conducted using the Swedish Malmö Diet and Cancer Study, with the outcome defined as a first dispensed antidepressant (ATC: N06A) and/or a first clinical depression diagnosis (ICD-10: F32/F33) during follow-up (2007–2011). Exposure was assessed through modelled annual mean concentrations of particulate matter (PM2.5, PM10), nitrogen oxides (NOx), and road traffic noise (Lden). Cox proportional hazards regression was applied, adjusted for potential confounders including sociodemographic and lifestyle factors.

Results:A total of 18 373 individuals were included, among whom 2224 with the outcome (89 % had dispensed antidepressant, 6 % both clinical diagnosis and antidepressant, and 5 % clinical diagnosis) during follow-up. Increased hazard ratios (HRs) were observed in association with long-term air pollution exposure, but only among women. Increased but statistically non-significant HRs were found for road traffic noise in women, while no associations were found in men. For lag1-5 (1–5 years exposure window prior to the event) in women, HRs per 10-unit increase were: PM2.5, 1.29 (95 % CI, 1.09–1.52); PM10, 1.10 (1.03–1.17); NOx, 1.15 (1.04–1.26); and Lden, 1.06 (0.99–1.13). Similar patterns were found for lag1 and in the two-pollutant models.

Conclusion:Long-term exposure to air pollution was positively associated with dispensed antidepressant medications in women but not in men. For road traffic noise, evidence was less clear, but a potential link was seen in women. Though associations were seen only in women, the findings suggest that air quality improvements and possibly also noise reductions may help reduce health burdens related to depressive symptoms.