Overview
- Emory University researchers examined more than 27.8 million Medicare beneficiaries aged 65 and older from 2000 to 2018, comparing Alzheimer’s diagnoses with local PM2.5 levels estimated by ZIP code.
- Long-term exposure to PM2.5 was associated with increased Alzheimer’s risk even after accounting for hypertension, stroke, depression and other conditions, with ABC News reporting mediation explained less than 5% of the link.
- The association was slightly stronger among people with a prior stroke, pointing to possible increased vulnerability related to neurovascular damage and blood–brain barrier compromise.
- Authors stress the study is observational and used environmental exposure estimates rather than personal monitoring, so it strengthens inference but does not prove causation.
- Researchers and external experts say the findings support air-quality improvements as a dementia-prevention strategy, alongside practical steps like monitoring air-quality ratings and using indoor filtration on high-pollution days.