Abstract Details

Title Air Pollution and Dementia: A Systematic Review and Meta-Analysis

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P1 - Poster Session 1 (8:00 AM-9:00 AM)

Poster/Presentation
Number 3-002

Objective Conduct a systematic review and meta-analysis of the association between exposure to air pollutants and clinical dementia.

Background Air pollution exposure is a possible modifiable risk factor for dementia and epidemiologic evaluation of this relation has grown rapidly. We synthesize the existing literature, considering differences by study factors that could influence findings.

Design/Methods We searched PubMed and Embase for studies describing associations between EPA criteria air pollutants or proxies of traffic pollution and clinical dementia through August 2021. We double extracted information on methodology and key findings for each study. Where at least three studies were identified using comparable approaches, results were meta-analyzed using random effects. We also evaluated whether there were differences observed by data source, study type, and variability in exposure reported.

Results Thirty-six studies were identified and 10 could be meta-analyzed for PM2.5. Results were expressed per μg/m³and standard deviation (SD; or interquartile range when SD was unavailable). Results across studies were somewhat more consistent using the latter approach. The overall HR for PM2.5 was 1.07 (95% CI: 1.04-1.10). The HR among 4 cohort studies was 1.19 (95% CI: 1.07-1.32) and among 6 studies using administrative data was 1.04 (95% CI: 1.00-1.07). There were suggestive associations with NO2 (HR=1.04; 95% CI: 0.99-1.10; n=5 studies, 1 cohort) and NOx (HR=1.06; 95% CI: 0.98-1.014; n=3 studies; 2 cohort), and no association with O3 (HR=0.98; 95% CI: 0.93-1.04; n=3 studies, 0 cohort).

Conclusions The evidence suggests that PM2.5 is a risk factor for dementia. However, meta-analyzed HRs are subject to limitations that require interpretation with great caution. Outcome ascertainment approaches differ across studies and each exposure assessment approach likely is a proxy for etiologically-relevant exposure as it relates to clinical dementia outcomes. Studies that evaluate critical periods of exposure, pollutants other than PM2.5, and that actively assess all participants for outcomes, are needed.

Authors/Disclosures
Elissa Wilker, Other PRESENTER	Dr. Wilker has received personal compensation for serving as an employee of Alexion. Dr. Wilker has received personal compensation for serving as an employee of Sanofi Genzyme. An immediate family member of Dr. Wilker has received personal compensation for serving as an employee of Biogen. An immediate family member of Dr. Wilker has received personal compensation for serving as an employee of Perkin Elmer. Dr. Wilker has stock in Alexion. Dr. Wilker has received research support from NIH.
	No disclosure on file
Marc Weisskopf, PhD (Harvard TH Chan School of Public Health)	Dr. Weisskopf has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Springer. The institution of Dr. Weisskopf has received research support from Biogen. The institution of Dr. Weisskopf has received research support from NIH.

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