The analyses revealed that PM2.5 was somewhat positively associated with the development of dementia, Alzheimer’s, and CIND. Specifically, the adjusted hazard ratios (HR) in relation to a 10 μg/m3 increase in PM2.5 for these three conditions were: 1.15 (95% CI=0.93-1.40), 1.32(95% CI=0.95-1.83) and 1.52 (95% CI=1.20-1.95), respectively. In contrast, NO2 concentrations were not associated with any of these three outcomes. The corresponding hazards ratios for a 5 ppb increase in NO2 for dementia, AD, and CIND were 0.98 (95% CI=0.93-1.03), 1.00(95% CI=0.91-1.09) and 0.99 (95% CI=0.83-1.06), respectively. Our findings also suggest that the association between PM2.5 and our measures of dementia are stronger among those who are obese when compared to those who are not.