Associations between types of residential greenspace and depressive symptoms in older adults: the Multi-Ethnic Study of Atherosclerosis

Abstract

Residential greenspace may prevent older-adult depression, but it is unclear whether this depends on type of greenspace and population subgroup. We examined associations between six greenspace measures and depressive symptoms among 6,799 U.S. older adults in the Multi-Ethnic Study of Atherosclerosis (1-3 observations per participant in 2000–2012). Depressive symptoms were assessed using the Center for Epidemiological Studies Depression scale. Time-varying residential address-linked exposures included street-view-based vegetation (grass, trees, other, and total), satellite-based Normalized Difference Vegetation Index (NDVI), and park access. In fully adjusted mixed-effects Poisson models, overall associations were null (symptom count ratios [CRs], 0.98–1.03 per SD increase). Associations varied by site, race/ethnicity, neighborhood socioeconomic status, and population density. In site-stratified analyses, fewer symptoms were associated with NDVI in New York, NY (CR=0.96, 95% CI: 0.92, 0.99), park access in Winston-Salem, NC (CR=0.95, 95% CI: 0.92, 0.99), and grass in Minneapolis, MN (CR=0.87, 95% CI: 0.79, 0.97). The greenspace metric most strongly associated with fewer symptoms differed across racial/ethnic groups. Greater street-level greenspace was associated with more symptoms in high-density areas. Greenspace–depression associations may therefore depend on greenspace type and context, suggesting that mental-health-oriented greenspace interventions should be tailored to local populations and environments.