Long-term effects of PM<inf>2.5</inf> components on incident dementia in the northeastern United States

• Type of Material: Article
• Authors: William Caudle, Emory University; Nelson Steenland, Emory University; Jing Li, Harvard T.H. Chan School of Public Health; Yifan Wang, Emory University; Pengfei Liu, Georgia Institute of Technology; Aaron van Donkelaar, Washington University in St. Louis; Randall V Martin, Washington University in St. Louis; Howard Chang, Emory University; Joel Schwartz, Harvard T.H. Chan School of Public Health; Petros Koutrakis, Harvard T.H. Chan School of Public Health; Liuhua Shi, Emory University
• Language: English
• Date: 2022-03-29
• Publisher: RELX
• Publication Version: Final Published Version
• Copyright Statement: © 2022 The Author(s)
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.xinn.2022.100208
• Title of Journal or Parent Work: The Innovation
• Volume: 3
• Issue: 2
• Start Page: 100208
• End Page: 100208
• Grant/Funding Information: This study was supported by the National Institute on Aging (NIA/NIH R01 AG074357), the HERCULES Center (P30 ES019776) and the Goizueta Alzheimer's Disease Research Center (ADRC) of Emory University (P50 AG025688), the U.S. Environmental Protection Agency (RD-835872), and NASA (80NSSC21K0508).
• Keywords: cohort study; air pollution; long-term exposure; PM2.5 components; dementia
• Research Categories: Engineering, Chemical; Biology, Biostatistics; Environmental Sciences

Abstract

Growing evidence has linked long-term fine particulate matter (PM2.5) exposure to neurological disorders. Less is known about the individual effects of PM2.5 components. A population-based cohort study investigated the association between long-term (1-year average) exposure to PM2.5 components and dementia incidence among the elderly population (age, ≥65 years) in the United States. We used data from the Medicare Chronic Conditions Warehouse and a high-resolution PM2.5 components dataset of the northeastern United States (2000–2017). We identified dementia diagnoses from patients’ hospital and medical insurance records and carried out Cox proportional hazards regression to investigate their association with PM2.5 components. Among ∼2 million participants, 15.1% developed dementia. From the single-pollutant models, hazard ratios per interquartile range increase were 1.10 (95% confidence interval [CI]: 1.09–1.11) for black carbon, 1.08 (95% CI: 1.07, 1.10) for inorganic nitrate, 1.03 (95% CI: 1.02, 1.04) for organic matter, 1.13 (95% CI: 1.11, 1.15) for sulfate, 1.07 (95% CI: 1.06, 1.07) for soil particles, and 1.04 (95% CI: 1.03, 1.05) for sea salt. Increase in exposure to black carbon and sulfate per interquartile range had the strongest associations with dementia incidence. Penalized spline models indicated that dementia incidence increased linearly with elevated black carbon concentrations, whereas the incidence of dementia was only elevated significantly following sulfate concentrations above ∼2 μg/m3. Our study suggests that long-term exposure to PM2.5 components is significantly associated with increased dementia incidence and that different components have different neurotoxicity. Reduction of PM2.5 emissions, especially for main sources of black carbon and sulfate, may reduce the burden of dementia in the aging United States population.