Blue spaces and incident dementia: Differences by geospatial and historical contexts

Blue spaces (i.e., water bodies) may benefit cognitive health depending on their uses and surrounding spatial context. We examined associations between blue spaces and incident dementia in the Cardiovascular Health Cognition Study, and specifically within Pittsburgh, given its industrial uses of blue spaces.

Participants were 2924 adults (Pittsburgh: n = 651) ≥65 years of age. Dementia was clinically adjudicated (1992-1999). Water density was measured using both 1 km radial buffers and U.S. Census tracts.

In Pittsburgh only, greater buffer-level blue space predicted a higher risk of mixed/vascular dementia (highest vs lowest tertile: hazard ratio [HR] = 2.87, 95% confidence interval [CI]: 1.43-5.74), but not Alzheimer's disease (p > 0.05). This was attenuated adjusting for individual/neighborhood confounders (HR = 2.65, 95% CI: 0.99-7.07). Tract-level associations were attenuated but significant after adjustment.

Blue space was related to vascular dementia risk after accounting for social context and using more personalized buffer-level measures. Future studies should carefully consider spatial units and differentiate blue spaces by historical uses.

Examined associations between nearby blue spaces and incident dementia. Tested multiple spatial units (buffer, tract) and separately for the Pittsburgh site. Blue space density was not related to dementia risk in overall sample. Greater blue space density predicted a higher risk of dementia for the Pittsburgh site. Associations were attenuated after adjusting for neighborhood confounders.