Greater Particulate Air Pollution Correlates with Greater Severity of Dementia
Exposure to particulate matter and other air pollution is generally agreed upon to be bad for long-term health. The worse the exposure, the worse the outcome. The epidemiological data is quite convincing, particularly studies in those parts of the world where, by happenstance, very similar populations are exposed to very different degrees of air pollution. The consensus on biological mechanisms is that pollutants interact with lung and airway tissues to provoke greater systemic inflammation. That inflammation in turn accelerates the onset and progression of all of the major fatal conditions of aging. Here the focus is on dementia, but other studies have shown similar influences on cardiovascular disease.
This cohort study used data associated with autopsy cases collected from 1999 to 2022 at the Center for Neurodegenerative Disease Research Brain Bank at the University of Pennsylvania. Data were analyzed from January to June 2025. Participants included 602 cases with common forms of dementia and/or movement disorders and older controls after excluding 429 cases with missing data on neuropathologic measures, demographic factors, APOE genotype, or residential address.
One-year mean PM2.5 concentration prior to death or prior to last Clinical Dementia Rating Sum of Boxes (CDR-SB) assessment was estimated using a spatiotemporal prediction model at residential addresses. Dementia severity was measured by CDR-SB scores. Ten dementia-associated neuropathologic measures representing Alzheimer's disease, Lewy body disease, limbic-predominant age-related TDP-43 encephalopathy, and cerebrovascular disease were graded or staged.
In a total of 602 autopsy cases (median age at death, 78 years), higher PM2.5 exposure prior to death was associated with increased odds of more severe Alzheimer disease neuropathologic change (ADNC) (odds ratio 1.19). In a subset of 287 cases with CDR-SB records (median age at death, 79 years), higher PM2.5 exposure prior to CDR-SB assessment was associated with greater cognitive and functional impairment (β = 0.48). Lastly, 63% of the association between higher PM2.5 exposure and greater cognitive and functional impairment was statistically mediated by ADNC (β = 0.30).