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Association of air quality improvement with slower decline of cognitive function in older women
Author(s) -
Younan Diana,
Wang Xinhui,
Millstein Joshua,
Petkus Andrew J,
Beavers Daniel P,
Espeland Mark A,
Chui Helena C,
Resnick Susan M,
Gatz Margaret,
Kaufman Joel D,
Wellenius Gregory,
Whitsel Eric A,
Manson JoAnn E,
Rapp Stephen R,
Chen JiuChiuan
Publication year - 2021
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.056162
Subject(s) - medicine , quartile , dementia , gerontology , cognitive decline , cognition , demography , epidemiology , environmental health , confidence interval , psychiatry , disease , pathology , sociology
Background Late‐life exposure to ambient air pollution is a modifiable risk factor for dementia, but epidemiological studies have shown inconsistent evidence for cognitive decline. Improved air quality (AQ) is associated with decreased mortality and improved respiratory health, but no studies have examined the association with cognitive function. Methods Participants included 2,232 U.S. community‐dwelling older women (aged 74‐92) from the Women’s Health Initiative Memory Study‐Epidemiology of Cognitive Health Outcomes (WHIMS‐ECHO) without dementia at enrollment. Measures of annual (2008‐18) cognitive function included general cognitive status (assessed by the Telephone Interview for Cognitive Status‐modified, TICSm) and episodic memory (assessed by the telephone‐based California Verbal Learning Test, CVLT). Regionalized universal kriging models were used to estimate annual exposures (1996‐2012) to fine particulate matter (PM 2.5 ) and nitrogen dioxide (NO 2 ) at residential locations, which were averaged over the 3‐year periods immediately preceding (recent exposure) and 10 years prior to (remote exposure) WHIMS‐ECHO enrollment. Individual‐level improvements in AQ were calculated as the reduction from remote to recent exposures. We used linear mixed effect models to examine the associations between improved AQ and the rates of cognitive decline in TICSm and CVLT trajectories, adjusting for sociodemographic, lifestyle, and clinical characteristics. Results AQ improved significantly for both PM 2.5 and NO 2 over the 10 years before enrollment. During a median of 6.2 (inter‐quartile‐range [IQR]=5.0) years of follow‐up, general cognitive status (β TICSm =‐0.42/year, 95% CI: ‐0.44, ‐0.40) and episodic memory (β CVLT =‐0.59/year, 95% CI: ‐0.64, ‐0.54) significantly declined. Greater AQ improvement was associated with slower decline in TICSm (β PM2.5 =0.026/year per IQR=1.79 µg/m 3 , 95% CI: 0.001, 0.05; β NO2 =0.034/year per IQR=3.92 ppb, 95% CI: 0.01, 0.06) and CVLT (β PM2.5 =0.070/year per IQR=1.79 µg/m 3 , 95% CI: 0.02, 0.12; β NO2 =0.060/year per IQR=3.97 ppb, 95% CI: 0.005, 0.12). The respective associations with TICSm and CVLT were equivalent to the slower declines found in women 0.9‐1.2 and 1.4‐1.6 years younger, and did not significantly differ by age, region, education, ApoE e4 genotypes, or cardiovascular risk factors. The benefits were attenuated after excluding incident dementia cases but remained after excluding prevalent or incident stroke cases. Conclusions Long‐term improvement in AQ in late‐life was associated with slower cognitive declines in older women.