Ambient air pollutants and indoor air quality are associated with cognitive impairment in older adults: A six‐year cohort study

Abstract

AbstractBackgroundExposure to air pollutants have known to increase the risk of cognitive impairment. Some older adults spend a long time indoors. However, limited studies have evaluated the effect of time staying indoors on the association between exposure to ambient air pollutants and cognitive function in older adults.MethodThis cohort study is part of the ongoing Taiwan Initiative for Geriatric Epidemiological Research (2011‐present). A total of 605 older adults were recruited at baseline (2011‐2013) with three biennial follow‐ups, and 496 participants were included after exclusion. The data of six air pollutants including sulphur dioxide, nitrogen dioxide, particulate matter in diameter ≤ 2.5µm (PM2.5) and 2.5‐10µm (PMcoarse), carbon monoxide, and ozone were obtained from 26 monitor stations of Taiwan Environmental Protection Administration (TEPA) between 1993 and 2019. Spatial‐Time Analysis Rendering with Bayesian Maximum Entropy was utilized to estimate the individual air pollutants’ exposure. Hours staying indoors were collected across four seasons. Generalized linear mixed model was utilized to explore the association between long‐term exposure to air pollutants and global or domain‐specific cognitive function (memory, attention, executive function, and language) over 6 years adjusted for some covariates. Stratified analyses were performed by median hours staying indoors every day.ResultThe mean age of the study participants were 72.4 years at baseline. PM2.5 was the only pollutant with a 14‐year average level (29.0 µm/m3) higher than the TEPA air quality standards. An interquartile range (IQR) increase in PM2.5 was associated with poor global cognition (β=‐0.19) and executive function (β=‐0.08), and the former effect became more evident in those with hours staying indoors < 13 hours/day (β=‐0.31). An IQR increase in PMcoarse was associated with poor global cognition (β=‐0.21) and verbal fluency (β=‐0.10), which became more evident in those stayed indoors ≥13 hours/day (β=‐0.32 and ‐0.13, respectively). Exposure to PMcoarse was associated with poor attention (β=‐0.15). No significant association was observed between other air pollutants and the performance of logical memory.ConclusionLong‐term exposure to PM2.5 or PMcoarse showed detrimental effect on cognitive function in community‐dwelling older adults and indoor air quality may play a role on these associations.