Overview

• Each interquartile increase in PM2.5 was associated with a 17% higher risk of Parkinson’s disease dementia and a 12% higher risk of dementia with Lewy bodies.
• Chronic PM2.5 exposure caused brain atrophy, neuronal loss and cognitive deficits in mice, while animals lacking alpha‑synuclein were largely protected.
• Researchers isolated a distinct, highly pathogenic alpha‑synuclein strain induced by PM2.5 (PM‑PFF) that shared key features with patient‑derived Lewy body pathology.
• Gene‑expression patterns in exposed mice strongly correlated with those from human brains with Lewy body dementia and Parkinson’s disease with dementia, but not Parkinson’s without dementia.
• Authors and independent experts call air quality a modifiable risk factor and priority for policy, while noting uncertainties over which PM components are most harmful and how genetic susceptibility shapes risk.