Alzheimer's linked to air pollution in study of 27.8 million Americans

A national cohort study of more than 27.8 million U.S. Medicare recipients aged 65+ (2000–2018) found long-term exposure to fine particulate air pollution was associated with a higher risk of Alzheimer's disease, with the link appearing largely direct rather than driven by common chronic conditions.

Researchers analyzed nationwide Medicare records to examine whether long-term air pollution exposure is linked to Alzheimer’s disease. The team followed more than 27.8 million U.S. adults aged 65 and older from 2000 through 2018 and assessed long-term fine particulate matter exposure alongside Alzheimer's diagnoses. The study examined the role of other chronic conditions and reported that these comorbidities had little additional explanatory effect. Authors conclude the association appears largely direct, rather than operating mainly through conditions such as hypertension, depression or stroke. Key findings: - The analysis covered a national cohort of over 27.8 million Medicare beneficiaries aged 65+ from 2000–2018. - Long-term exposure to fine particulate air pollution was associated with an increased risk of Alzheimer’s disease; the association was reported as slightly stronger among people with a history of stroke while other comorbidities contributed little extra effect. - The research is published in PLOS Medicine (2026) by Deng and colleagues and is presented as a national cohort study. Summary: The authors report that long-term fine particulate exposure is associated with higher Alzheimer’s risk and that this relationship appears to operate largely through direct effects on the brain rather than primarily via common chronic conditions. Undetermined at this time.