Exposure to green and blue spaces and depression in older adults: Findings from the EPIPorto cohort

BACKGROUND: Portugal is amongst the European countries with the largest share of older adults and highest prevalence of depression. Natural environments may play an important role promoting population-level mental health. We investigated the associations between the exposure to green and blue spaces and depression among older adults from Porto (Portugal) and the mediation role of social interactions and physical exercise. METHODS: This study included data from the fourth wave (2017) of the EPIPorto cohort, which included only participants aged ≥60. The presence of depressive symptoms was measured using the Geriatric Depression Scale (GDS). Using the residential locations, we computed the Normalized Difference Vegetation Index (NDVI), and the shortest distance to the nearest urban green space and blue space. We fitted crude and adjusted negative binomial regression models. Associations were expressed using relative risks (RR) and 95% intervals (95% CI). We used structural equation modelling to assess mediation. RESULTS: We included 639 participants, from which 27.2% presented depression (GDS ≥5). In the adjusted models, we found statistically significant associations between having more NDVI within 50 and 100 meters and lower GDS (RR = 0.78 [95%CI 0.65-0.94] and RR = 0.81 [95%CI 0.67-0.97], respectively). Most of the association between NDVI and the GDS was direct, being only slightly mediated by the time spent with family, although both the direct and indirect effects did not reach statistical significance. No significant associations with the remaining variables of exposure were identified. CONCLUSIONS: We observed a direct association between living in areas with more vegetation and less depressive symptoms in older adults in Porto. KEY MESSAGES: • Our results suggest that the provision of green space may be an effective strategy to promote mental health in late life.