Long-term exposure to air pollution and cognitive aging: Findings from a United States cohort of older adults

Background: Growing epidemiologic evidence suggests long-term exposure to air pollution increases the risk of Alzheimer's disease and related dementias (ADRD) in older adults but research on its effect on early indicators of ADRD is limited. Objective: We examined the effect of fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) on cognitive performance and decline in a cohort of older adults. Methods: This analysis draws from the Ginkgo Evaluation of Memory Study, a clinical trial aimed at understanding ADRD prevention. Participants aged 75 years and older completed an annual neuropsychological battery for up to 8 years. Air pollution was estimated using fine-scale models and accounted for residential history. Cognitive performance at baseline and trajectories of cognitive function across levels of air pollution were estimated using linear mixed regression models. Longitudinal analyses incorporated inverse probability weights to account for differential selection across visits. Results: This study included 3044 individuals. Exposure to PM_2.5was associated with slightly worse performance at intercepts for all domains. Higher exposure was not associated with faster declines in cognitive performance over follow-up. Results for NO₂follow a similar pattern. Conclusions: Findings support associations between exposure to higher concentrations of air pollution and worse cognitive performance at baseline, but not cognitive decline.