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. 2023 Oct 1;183(10):1080-1089.
doi: 10.1001/jamainternmed.2023.3300.

Comparison of Particulate Air Pollution From Different Emission Sources and Incident Dementia in the US

Boya Zhang  1 , Jennifer Weuve  2 , Kenneth M Langa  3   4   5   6 , Jennifer D'Souza  1 , Adam Szpiro  7 , Jessica Faul  3 , Carlos Mendes de Leon  8 , Jiaqi Gao  1 , Joel D Kaufman  9   10   11 , Lianne Sheppard  7   10 , Jinkook Lee  12 , Lindsay C Kobayashi  1 , Richard Hirth  13   14 , Sara D Adar  1
Affiliations

Comparison of Particulate Air Pollution From Different Emission Sources and Incident Dementia in the US

Boya Zhang et al. JAMA Intern Med. .

Abstract

Importance: Emerging evidence indicates that exposure to fine particulate matter (PM2.5) air pollution may increase dementia risk in older adults. Although this evidence suggests opportunities for intervention, little is known about the relative importance of PM2.5 from different emission sources.

Objective: To examine associations of long-term exposure of total and source-specific PM2.5 with incident dementia in older adults.

Design, setting, and participants: The Environmental Predictors of Cognitive Health and Aging study used biennial survey data from January 1, 1998, to December 31, 2016, for participants in the Health and Retirement Study, which is a nationally representative, population-based cohort study in the US. The present cohort study included all participants older than 50 years who were without dementia at baseline and had available exposure, outcome, and demographic data between 1998 and 2016 (N = 27 857). Analyses were performed from January 31 to May 1, 2022.

Exposures: The 10-year mean total PM2.5 and PM2.5 from 9 emission sources at participant residences for each month during follow-up using spatiotemporal and chemical transport models.

Main outcomes and measures: The main outcome was incident dementia as classified by a validated algorithm incorporating respondent-based cognitive testing and proxy respondent reports. Adjusted hazard ratios (HRs) were estimated for incident dementia per IQR of residential PM2.5 concentrations using time-varying, weighted Cox proportional hazards regression models with adjustment for the individual- and area-level risk factors.

Results: Among 27 857 participants (mean [SD] age, 61 [10] years; 15 747 [56.5%] female), 4105 (15%) developed dementia during a mean (SD) follow-up of 10.2 [5.6] years. Higher concentrations of total PM2.5 were associated with greater rates of incident dementia (HR, 1.08 per IQR; 95% CI, 1.01-1.17). In single pollutant models, PM2.5 from all sources, except dust, were associated with increased rates of dementia, with the strongest associations for agriculture, traffic, coal combustion, and wildfires. After control for PM2.5 from all other sources and copollutants, only PM2.5 from agriculture (HR, 1.13; 95% CI, 1.01-1.27) and wildfires (HR, 1.05; 95% CI, 1.02-1.08) were robustly associated with greater rates of dementia.

Conclusion and relevance: In this cohort study, higher residential PM2.5 levels, especially from agriculture and wildfires, were associated with higher rates of incident dementia, providing further evidence supporting PM2.5 reduction as a population-based approach to promote healthy cognitive aging. These findings also indicate that intervening on key emission sources might have value, although more research is needed to confirm these findings.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Weuve reported receiving personal fees from Health Effects Institute and Alzheimer’s Association outside the submitted work. Dr Langa reported receiving grants from the National Institute on Aging (NIA) during the conduct of the study and grants from the NIA and Alzheimer’s Association outside the submitted work. Dr Szpiro reported receiving grants from the National Institutes of Health (NIH) during the conduct of the study. Dr Faul reported grants receiving from the NIA outside the submitted work. Dr Kaufman reported receiving grants from the NIH and US Environmental Protection Agency during the conduct of the study. Dr Lee reported receiving grants from the NIH during the conduct of the study. Dr Sheppard reported receiving grants from the NIH and Health Effects Institute, both indirectly related to this work, during the conduct of the study and personal fees from the US Environmental Protection Agency as chair of the Clean Air Scientific Advisory Committee outside the submitted work. Dr Hirth reported receiving grants from the NIH during the conduct of the study. Dr Adar reported receiving grants from the National Institutes of Environmental Health Sciences and NIA during the conduct of the study and grants and personal fees from the Health Effects Institute outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. The Spatial Distribution of Source-Specific Fine Particulate Matter (PM2.5) Across the US in 2017
Figure 2.
Figure 2.. Hazard Ratios (95% CIs) of Incident Dementia in the Health and Retirement Study (1998-2016) Associated With Interquartile Differences in 10-Year Mean Concentrations of Source-Specific Fine Particulate Matter (PM2.5) in Single Pollutant and Multipollutant Models
The IQRs for each total and source-specific PM2.5 with concentrations are given in parentheses in micrograms per cubic meter. Model 1 is the single-pollutant model, stratified by 2-year birth cohorts and 2-year age at baseline and adjusted for sex, race, educational attainment, ownership of the primary residence, total household wealth, urbanicity, neighborhood socioeconomic status, and a flexible set of unpenalized thin-plate regression splines with 10 df. Model 2 is model 1 plus other PM2.5. Model 3 is model 2 plus coarse PM, nitrogen dioxide, and ozone.
See this image and copyright information in PMC

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