The Relationship between Green Space Exposure and Incidence of Depression and Dementia After Enrollment in the All of Us Research Program

Background: Exposure to green space has been linked to better mental health, but the long-term effects of early-life greenness on neuropsychiatric outcomes remain unclear. This study examined whether surrounding green space at the time of the enrollment influences the subsequent risk of developing depression or dementia and whether these associations vary across demographic groups. Methods: Satellite-derived Normalized Difference Vegetation Index (NDVI) was used to quantify green space exposure and linked to long-term health records from 465,876 participants in the All of Us Research Program. Associations with incident depression and dementia were estimated using hazard ratios, dose–response curves, cumulative incidence functions, subgroup analyses, and sensitivity analyses. Results: Higher NDVI was consistently associated with a modestly lower risk of depression across exposure windows, age groups, and sexes. These associations remained robust in subgroup and sensitivity analyses. In contrast, no meaningful association was observed between NDVI and dementia risk. Conclusion: Living in greener areas appears to confer a small but measurable reduction in the risk of developing depression, while no protective effect was found for dementia. These findings highlight the importance of urban greening and equitable access to natural environments as potential public health strategies for promoting mental well-being.