Abstract

Background:

Research on the relationship between long-term exposure to particulate matter with aerodynamic diameter $\le 2.5\mathrm{\mu }\mathrm{m}$ (${\mathrm{PM}}_{2.5}$) and poor cognitive function is lacking in developing countries, especially in highly polluted areas.

Objectives:

We evaluated associations of long-term exposure to ${\mathrm{PM}}_{2.5}$ with poor cognitive function in a diverse, national sample of older adults in China.

Methods:

This analysis included data on 13,324 older adults (5,879 who were 65–79 years of age, 3,052 who were 80–89 years of age, 2,634 who were 90–99 years of age, and 1,759 who were $\ge 100\text{\hspace{0.17em}years}$ of age) with normal cognitive function at baseline from March 2002 to September 2014, with 64,648 person-years of follow-up. We used a geographic information system analysis to estimate the annual average satellite-derived ${\mathrm{PM}}_{2.5}$ concentration for the geocoded location of the participants’ baseline residences. Poor cognitive function was defined as a score of less than 18 on the Chinese version of the Mini-Mental State Examination (MMSE). Competing risk models were performed to explore the association of ${\mathrm{PM}}_{2.5}$ with poor cognitive function.

Results:

Each $10\text{-}\mathrm{\mu }\mathrm{g}/{\mathrm{m}}^3$ increase in ${\mathrm{PM}}_{2.5}$ was associated with a 5.1% increased risk of poor cognitive function [adjusted hazard ratio (HR): 1.051; 95% confidence interval (CI): 1.023, 1.079]. Compared to the lowest quartile of ${\mathrm{PM}}_{2.5}$ ($<41.4\mathrm{\mu }\mathrm{g}/{\mathrm{m}}^3$), adjusted $\text{HR}$ values were 1.20 (95% CI: 1.09, 1.33), 1.27 (95% CI: 1.15, 1.41), and 1.21 (95% CI: 1.09, 1.34) for the second ($\ge 41.4–50.3\text{\hspace{0.17em}ug}/{\mathrm{m}}^3$), third ($\ge 50.3–60.7\mathrm{\mu }\mathrm{g}/{\mathrm{m}}^3$), and fourth ($\ge 60.7\mathrm{\mu }\mathrm{g}/{\mathrm{m}}^3$) quartiles of ${\mathrm{PM}}_{2.5}$, respectively (p for trend $<0.001$). Subgroup analyses suggested stronger associations between ${\mathrm{PM}}_{2.5}$ and poor cognitive impairment in men than women. The association was positive in the 65- to 79- and $\ge 100\text{-}\mathrm{y}$ age group but not significant and positive in the other two age groups with similar results.

Conclusion:

${\mathrm{PM}}_{2.5}$ was identified as a risk factor for poor cognitive function in Chinese older adults. Improving air quality may reduce the future population burden of poor cognitive function, especially in areas with high air pollution. https://doi.org/10.1289/EHP5304