Association between ambient fine particular matter components and subsequent cognitive impairment in community-dwelling older people: a prospective cohort study from eastern China

Fine particular matter (PM_2.5) has been associated with dementia, but limited information is available regarding the association between PM_2.5 components and dementia.

We aimed to identify the major components of PM_2.5 that affect cognitive function to further investigate its mechanism of action, and develop a prevention strategy for dementia.

In this study, we included 7804 participants aged ≥ 60 years recruited from seven counties in Zhejiang province, eastern China. The participants completed the baseline survey between 2014 and 2015, and were followed up until the end of 2020. We adopted single-component robust Poisson regression models for analyses, and estimated relative risks and 95% confidence intervals describing associations between the chemical constituents of PM_2.5 exposure and incident cognitive impairment in those who were free from cognitive impairment at baseline.

Significantly positive associations were observed between sulfate, nitrate, ammonium, and organic matter in PM_2.5 and incident cognitive impairment across different exposure periods; the relative risks of 10-year exposure before enrollment ranged from 1.01 to 1.02. However, we did not find a significant association between black carbon and cognitive impairment. The point estimates of the relative risk values did not change substantially after performing the sensitivity analyses.

Our findings strengthen the idea that long-term exposure to PM_2.5 mass and its chemical components is associated with an elevated risk of incident cognitive impairment among older adults.