Associations between air pollution exposure and subtypes of cognitive performance in older women

Abstract

AbstractBackgroundAir pollution exposure is a novel environmental risk factor in brain aging. It remains unclear whether long‐term exposure in older adulthood is associated with profiles of cognitive performance across multiple domains.MethodParticipants included 2,185 women (aged 66‐83 years) without dementia from the Women’s Health Initiative Study of Cognitive Aging. Baseline neuropsychological assessment included tests of verbal episodic memory (California Verbal Learning Test), figural memory (Benton’s Visual Recognition Test), language (letter and category fluency), attention (Digit Span Forward and Backwards), and visuospatial ability (Card Rotations Test). Testes were adjusted for demographic age, education, and race/ethnicity. Average annual levels of particulate matter of aerodynamic diameter<2.5 (PM2.5) and nitrogen dioxide (NO2) were estimated at the participant’s residence using regionalized national universal kriging models and averaged over the 3‐year period before the baseline assessment. Latent class structural equation models (SEM) were constructed to identify latent classes of women who had similar patterns of performance across cognitive tests. After identifying the number of latent classes extract in the model, we constructed a second SEM to examine associations between air pollution exposure and latent class membership using multinomial regression while adjusting for demographic, lifestyle, and clinical confounders.ResultFive significant latent classes were identified (Figure 1): multidomain cognitive impairment (n=247; 11%), amnestic cognitive impairment (n=263; 12%), superior memory (n=407; 19%), superior attention (n=351; 16%), and average cognitive ability (n=917; 42%). Women living in locations with higher levels of PM2.5 (per interquartile range [IQR] = 3.63 μg/m3) or NO2 (per IQR = 10.33) were more likely to be classified as having amnestic cognitive impairment compared to having average cognitive ability (OR=1.27; p=.021). One IQR increase in NO2 was also associated with decreased likelihood of having superior memory (OR=.81; p=.024) compared to average cognitive ability.ConclusionOur cross‐sectional study illustrates that long‐term exposure to PM2.5 and NO2 may be associated with specific patterns of cognitive performance; mainly worse episodic memory relative to performance in other domains. Our findings provide further evidence that air pollution may exert neurotoxic effects on brain areas underlying episodic memory in older women.