Per-Capita Food Availability and Global Dementia Burden Across Multiple Exposure Windows

Background/Objectives: Per-capita food availability may represent a large-scale indicator of nutritional environments potentially associated with dementia risk. However, whether national dietary environments are associated with dementia burden across different exposure periods remains unclear. Methods: We linked model-derived estimates of per-capita food availability based on Food and Agriculture Organization (FAO) food supply data for 2005, 2010, and 2015 with 2018 age-standardized dementia incidence, prevalence, and mortality across 109 countries. Multivariable ordinary least-squares models were estimated with adjustment for socioeconomic, demographic, environmental, and metabolic covariates. Results: Higher per-capita food availability was positively associated with dementia outcomes in minimally adjusted models, particularly for the 2005 exposure window, although these associations were substantially attenuated after full covariate adjustment. In contrast, the 2010 exposure window showed positive associations with dementia incidence and prevalence after full adjustment using the conventional significance threshold (α = 0.05), whereas no significant associations were observed for mortality or for the 2015 exposure window. Sensitivity analyses indicated that associations varied according to exposure timing and model specification. Conclusions: Overall, these findings suggest that large-scale nutritional environments are associated with variations in dementia burden across countries, although the substantial temporal overlap among exposure measures precludes inference regarding temporally specific effects; these associations should therefore be interpreted within the broader socio-demographic and metabolic context in which national food environments are embedded.