Air pollution may increase risk of Alzheimer’s disease and related dementias (ADRD) in the U.S., but the extent of this relationship is unclear. Here, we constructed two national U.S. population-based cohorts of those aged ≥65 from the Medicare Chronic Conditions Warehouse (2000–2018), combined with high-resolution air pollution datasets, to investigate the association of long-term exposure to ambient fine particulate matter (PM 2.5), nitrogen dioxide (NO 2), and ozone (O 3) with dementia and AD incidence, respectively. We identified ~2.0 million incident dementia cases ( N = 12,233,371; dementia cohort) and ~0.8 million incident AD cases ( N = 12,456,447; AD cohort). Per interquartile range (IQR) increase in the 5-year average PM 2.5 (3.2 µg/m 3), NO 2 (11.6 ppb), and warm-season O 3 (5.3 ppb) over the past 5 years prior to diagnosis, the hazard ratios (HRs) were 1.060 (95% confidence interval [CI]: 1.054, 1.066), 1.019 (95% CI: 1.012, 1.026), and 0.990 (95% CI: 0.987, 0.993) for incident dementias, and 1.078 (95% CI: 1.070, 1.086), 1.031 (95% CI: 1.023, 1.039), and 0.982 (95%CI: 0.977, 0.986) for incident AD, respectively, for the three pollutants. For both outcomes, concentration-response relationships for PM 2.5 and NO 2 were approximately linear. Our study suggests that exposures to PM 2.5 and NO 2 are associated with incidence of dementia and AD.
Air pollution has been linked to neurodegenerative disease. Here the authors carried out a population-based cohort study to investigate the association between long-term exposure to PM 2.5, NO 2, and warm-season O 3 on dementia and Alzheimer’s disease incidence in the United States.