A Longitudinal Analysis of the Association Between Long-Term Exposure to Air Pollution and Cognitive Function Among Adults Aged 45 and Older in China

OBJECTIVES: Evidence suggests long-term exposure to fine particulate matter air pollution (PM(2.5)) is associated with a higher risk of cognitive impairment, especially among older adults. This study examines the relationship between PM(2.5) exposure and cognitive function in China’s aging population. METHODS: We used longitudinal data from the China Health and Retirement Longitudinal Study (2011–2015) linked with historical PM(2.5) concentrations (2000–2015) from remotely sensed satellite data. Growth curve models were applied to estimate associations between PM(2.5) exposure (measured in intensity, duration, and a joint variable of intensity with duration for cumulative exposure) and cognitive function. RESULTS: Relative to the lowest exposure group, exposure in the second group of PM(2.5) intensity (35–50 μg/m(3)) is associated with poorer cognitive function, but higher levels of PM(2.5) appear to be associated with better cognitive function, indicating a U-shaped association. Similar patterns are seen for fully adjusted models of PM(2.5) duration: the second group (13–60 months) is associated with worse cognitive function than the first group (0–12 months), but coefficients are nonsignificant in longer duration groups. Joint analysis of PM(2.5) intensity with duration suggests that duration may play a more detrimental role in cognitive function than intensity. However, we do not find a statistically significant association between PM(2.5) exposure and the rate of cognitive decline. DISCUSSION: Our findings are mixed and suggest that some categories of higher and longer exposure to PM(2.5) are associated with poorer cognitive function, while that exposures do not hasten cognitive decline. However, more work is necessary to disentangle PM(2.5) exposure from individuals’ background characteristics, particularly those jointly associated with cognitive function and urban living.