Non-traditional socio-environmental and geospatial determinants of Alzheimer's disease-related dementia mortality

Importance: Recent data point to the impact of non-traditional environmental and social factors on Alzheimer's Disease-Related Dementias (ADRD) mortality. Our study aimed to determine the extent to which antecedent air pollution, social vulnerability, and geospatial features in the environment associate with ADRD mortality. Design: This was a cross-sectional study conducted across the mainland United States. County level Social Vulnerability Index (SVI), particulate matter air pollution (PM_2.5) were linked to ADRD mortality. Patient Rule Induction Method (PRIM) was used for delineating and characterizing “bumps” or spikes in mortality. SHapley Additive exPlanations (SHAP) values were used to rank variables by predictivity and association with directional changes in ADRD mortality. Exposures: PM_2.5 data was acquired from 1 × 1 km spatial grids using aerosol optical depth from the Atmospheric Analysis Composition Group at Washington University St. Louis. SVI was acquired from the CDC's ATSDR Data, which is a composite index scale that characterizes socio-environmental vulnerability. Google Street View imagery coupled with deep learning computational techniques was used to extract features of neighborhood level environment characteristics from across the United States. Results: There was a significant interaction effect between PM_2.5 and SVI on ADRD mortality (β = 31.100, p < 0.001). Two clusters of elevated ADRD mortality were identified: counties with high PM_2.5 and SVI (HH) and with low PM_2.5 and SVI (LL). Analysis of LL subset revealed associations between ADRD mortality and specific SVI subdomains, as well as built environment variables. Geospatial mapping indicated a split in these clusters along northern and southern latitudes, with differences in temperature and sunlight intensity (p < 0.001) rather than urbanization driving the distribution. Conclusions: Ambient air pollution interacts with SVI to influence ADRD mortality rates. Our findings support a role for non-traditional factors including elements of the built environment, geographical location, and natural environmental exposures contributing to ADRD mortality.