Overview

• An autopsy study from the University of Pennsylvania published in JAMA Neurology found that each 1 μg/m3 higher 1-year PM2.5 exposure was linked to a 19% greater likelihood of severe Alzheimer’s amyloid and tau buildup.
• Clinical records for a subset showed that individuals with higher PM2.5 exposure had greater cognitive and functional impairment and faster symptom onset.
• A Science study analyzing more than 56 million U.S. hospital records reported a 12% higher hospitalization risk for Lewy body dementia and Parkinson’s disease dementia in areas with higher long-term PM2.5.
• Mouse experiments in the Science report showed PM2.5 exposure led to memory deficits, medial temporal lobe atrophy, and α‑synuclein aggregation, with gene-expression changes overlapping those seen in human dementia.
• Authors note limitations including high-dose, short-duration exposures in mice and area-level pollution estimates that do not capture individual factors such as secondhand smoke or occupational chemicals.