2X increased risk of Alzheimer's Disease if lots of air pollution - meta-analysis Jan 2020
Air Pollution and Alzheimer’s Disease: A Systematic Review and Meta-Analysis
Journal of Alzheimer’s Disease Volume 77, Issue 2 https://doi.org/10.3233/JAD-200483
Pengfei Fu and Ken Kin Lam Yung kklyung at hkbu.edu.hk
Background:
Ambient air pollution has been associated with Alzheimer’s disease (AD) in the elderly. However, its effects on AD have not been meta-analyzed comprehensively.
Objective:
We conducted a systematic review and meta-analysis to assess the associations between air pollution and AD incidence.
Methods:
We searched PubMed and Web of Science for indexed publications up to March 2020. Odds risk (OR) and confidence intervals (CI) were estimated for particulate matter (PM)10 (PM10), PM2.5, ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). The subgroup analysis was conducted based on the pollution levels.
Results:
Nine studies were included in the meta-analysis and review. The OR per 10μg/m3 increase of PM2.5 was 1.95 (95% CI: 0.88–4.30). The corresponding values per 10μg/m3 increment of other pollutants were 1.03 (95% CI: 0.68–1.57) for O3, 1.00 (95% CI: 0.89–1.13) for NO2, and 0.95 (95% CI: 0.91–0.99) for PM10 (only one study), respectively. Overall OR of the five air pollutants above with AD was 1.32 (95% CI: 1.09–1.61), suggesting a positive association between ambient air pollution and AD incidence.
The sub-analysis indicated that the OR (2.20) in heavily polluted regions was notably higher than that in lightly polluted regions (1.06). Although AD risk rate data related to SO2 or CO exposure are still limited, the epidemiologic and toxicological evidence indicated that higher concentration of SO2 or CO exposure increased risks of dementia, implying that SO2 or CO might have a potential impact on AD.
Ambient Air Pollution and the Severity of Alzheimer Disease Neuropathology
JAMA Neurol doi: 10.1001/jamaneurol.2025.3316 PDF behid $45 paywall
Boram Kim, MD1; Kaitlin Blam, BA1; Holly Elser, MD, PhD2,3
Key Points
- Question What are the associations between air pollution, neuropathology, and dementia?
- Findings In this study of 602 autopsy-confirmed individuals, exposure to higher levels of fine particulate matter air pollution (PM2.5) was associated with more advanced Alzheimer disease neuropathologic change (ADNC) and more advanced clinical measures of dementia. The association between PM2.5 exposure and clinical dementia severity appeared to be statistically mediated by ADNC.
- Meaning Higher PM2.5 exposure may exacerbate Alzheimer disease neuropathologic change and cognitive dysfunction in the setting of dementia; population-based autopsy studies are further needed to generalize these findings.
Abstract
Importance Exposure to fine particulate matter air pollution (PM2.5) may increase risk for dementia. It is unknown whether this association is mediated by dementia-related neuropathologic change found at autopsy.
Objective To examine associations between PM2.5 exposure, dementia severity, and dementia-associated neuropathologic change.
Design, Setting, and Participants 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.
Exposures 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.
Main Outcomes and Measures Dementia severity was measured by CDR-SB scores. Ten dementia-associated neuropathologic measures representing Alzheimer disease, Lewy body disease, limbic-predominant age-related transactive response DNA-binding protein (TDP)-43 encephalopathy, and cerebrovascular disease were graded or staged. Linear, logistic, and structural equation models were used to examine the associations between PM2.5, CDR-SB, and neuropathologic measures, adjusting for demographic factors and APOE ε4 allele status.
Results In a total of 602 autopsy cases (median [IQR] age at death, 78 [71-85] years; 328 male [54.5%] and 274 female [45.5%]), higher PM2.5 exposure prior to death was associated with increased odds of more severe Alzheimer disease neuropathologic change (ADNC) (odds ratio, 1.19; 95% CI, 1.11-1.28). In a subset of 287 cases with CDR-SB records (median [IQR] age at death, 79 [72-86] years; 154 [53.7%] male and 133 female [46.3%]), higher PM2.5 exposure prior to CDR-SB assessment was associated with greater cognitive and functional impairment (β = 0.48; 95% CI, 0.22-0.74). Lastly, 63% of the association between higher PM2.5 exposure and greater cognitive and functional impairment was statistically mediated by ADNC (β = 0.30; 95% CI, 0.04-0.53).
Conclusions and Relevance In this study, PM2.5 exposure was associated with increased dementia severity and increased ADNC. Population-based studies are needed to better understand this relationship.
Clips from Medscape review of the study
- The median 1-year mean PM2.5 concentration before death was 9.4 µg/m3. In adjusted models, higher PM2.5 exposure correlated to increased odds of more severe AD neuropathology.
- For example, for every 1 µg/m3 increase in 1-year mean PM2.5 exposure before death, researchers found a 17% higher odds of a higher Thal amyloid phase, 20% higher odds of higher Braak stage, 20% higher odds of lower CERAD score, and 19% increased odds of increased overall ADNC.
- Each of these factors was significant (P < .001).
Related in VitaminDWiki
- 1.4 X more likely to be Vitamin D deficient if high PM2.5 (why: indoors, less UV, inflammation) - May 2025
- 17 Ways to Cut Your Risk of Stroke, Dementia and Depression (Vitamin D cuts 10 of them) - April 2025
- Air Pollution reduces Vitamin D production - many studies
- Cognitive decline is 19X more likely if low vitamin D
- Every single risk factor listed for Alzheimer's Disease is also a risk factor for low vitamin D levels
- (Vitamin D reduces Alzheimer’s disease in at least 11 ways – Jan 2013|Vitamin D reduces Alzheimer’s disease in 11 ways))