Exposure to traffic pollution and increased risk of depressive and anxiety symptoms in older adults

Abstract

Background: Mental health disorders are the third most costly non-fatal condition in America, and account for >140 million disability-adjusted life years worldwide. While the genetic profile is been major risk factor of mental disorders, recent evidence has suggested a role of traffic-related air pollution in the pathogenesis of mental disorders. Methods: We examined the association of distance to road, a marker of traffic pollution exposure, with depression and anxiety in 4,854 community-dwelling adults (aged ≥57) of the National Social Life, Health and Aging Project, a nationally representative, longitudinal sample of older adults in the US. Depression and anxiety were evaluated using standardized questionnaires, with cases identified by dichotomizing questionnaire scores using well-established cutoffs. As a proxy for traffic exposure, we calculated distance from each residential address to the closest A1–A3 road segments. Generalized linear mixed models were used to assess the association with adjustment of confounders (e.g., socioeconomic status), and to explore effect modification (e.g., by season). Results: In models adjusted for age, gender, race, calendar year, season, day of week, region and individual- and neighborhood-level socioeconomic status, we found 1.38 times the odds of adverse depressive symptoms (95%CI: 1.07, 1.78), and 1.51 times the odds of adverse anxiety symptoms (95%CI: 1.16, 1.96) in individuals living within 50m of a road, compared with those living 200m or farther away. We saw no elevations in odds for adults living 50–200 m from the road. The association remains robust upon adjustment of fine particular matter (PM2.5). Association with other neighborhood characteristics (e.g., crime/foreclosure rate, greenness) will be examined. Conclusions: Distance to road was associated with depression and anxiety, suggesting that pollution from traffic may be a newly identified environmental risk factor for mental health.