Exposure to green and blue spaces and depression among older adults from the EPIPorto cohort: examining environmental, social, and behavioral mediators and varied space types

This study investigated the associations between exposure to different types of natural spaces and depression among urban older adults and explored the potential mediators. We used data on 631 participants aged ≥60 from the EPIPorto cohort (Porto, Portugal). Depressive symptoms were measured using the Geriatric Depression Scale. We assessed greenness in residential surroundings using the Normalized Difference Vegetation Index (NDVI) and evaluated accessibility to green and blue spaces. Metrics were calculated separately for agricultural, natural, and urban green spaces. We used logistic regression to estimate associations and mediation analysis to examine the mediating effects of air pollution, temperature, physical exercise, social support, and social activities. Living near urban green spaces was associated with lower odds of depression (OR = 0.21, 95% CI 0.03–0.74). Contrastingly, natural and agricultural green spaces were associated with higher odds of depression (OR = 1.69, 1.02–2.79 and OR = 1.80, 1.23–2.64, respectively). No associations were found for NDVI, accessibility to blue spaces, or green space size. Social support explained a significant proportion (33.9%, p = 0.044) of the total effect between the type of nearest green space and depression. These findings suggest that enhancing the accessibility of urban green spaces holds promise as a strategy for mitigating depression among older adults.