The effect of China's Clean Air Act on cognitive function in older adults: a population-based, quasi-experimental study.

Journal Article (Journal Article)

Background

Air pollution might accelerate cognitive ageing; it is unclear whether large-scale interventions, such as China's Clean Air Act (CCAA), can mitigate cognitive deterioration. We aimed to evaluate the effect of CCAA on changes in cognitive function in older adults.

Methods

In this population-based, quasi-experimental study, we did a difference-in-differences analysis of the data collected during the 2014 and 2018 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). The study design used a counterfactual analysis feature by dividing CLHLS participants into two groups. The intervention group included participants who lived in areas where the provincial government set a target of reducing particulate matter (PM) by at least 5% annually from 2014 onward, whereas the control group consisted of individuals who lived in areas without a PM reduction target. Global cognitive function was measured using the Mini-Mental State Examination (MMSE). We used fixed-effects models to examine the between-group differences in MMSE score changes before and after CCAA implementation. We associated longitudinal changes in MMSE scores with changes in concentrations of PM with a diameter of less than 2·5 μm (PM2·5 ) concentration and other regulated pollutants. We used alternative models and sensitivity analyses to evaluate the robustness of the results from the main models.

Findings

2812 individuals participated in the 2014 and 2018 surveys (mean age 81·0 years [SD 9·3] in 2014; 1408 [50·1%] female and 1404 [49·9%] male). 2251 (80·0%) were included in the intervention group and 561 (20·0%) in the control group. After controlling for potential confounders, the intervention group had a significantly smaller decline in MMSE scores from 2014 to 2018 compared with the control group: the mean between-group difference was 2·45 points (95% CI 1·32-3·57). Interquartile increases in PM2·5 were associated with a significant MMSE score decline of 0·83 points (95% CI 0·24-1·42); similarly, increases in SO2 were also associated with a significant MMSE score decline of 0·80 points (0·32-1·29).

Interpretation

Implementing stringent clean air policies might mitigate the risk of air pollutant-associated cognitive ageing in older people.

Funding

National Natural Sciences Foundation of China, National Key R&D Program of China, China Postdoctoral Science Foundation funded project, the Duke/Duke-National University of Singapore Collaboration Pilot Project, the National Institute on Aging and Peking University-Baidu Fund, Energy Foundation, and the Fundamental Research Funds for the Central Universities.

Full Text

Duke Authors

Cited Authors

  • Yao, Y; Lv, X; Qiu, C; Li, J; Wu, X; Zhang, H; Yue, D; Liu, K; Eshak, ES; Lorenz, T; Anstey, KJ; Livingston, G; Xue, T; Zhang, J; Wang, H; Zeng, Y

Published Date

  • February 2022

Published In

Volume / Issue

  • 3 / 2

Start / End Page

  • e98 - e108

PubMed ID

  • 35224526

Pubmed Central ID

  • PMC8881012

Electronic International Standard Serial Number (EISSN)

  • 2666-7568

International Standard Serial Number (ISSN)

  • 2666-7568

Digital Object Identifier (DOI)

  • 10.1016/s2666-7568(22)00004-6

Language

  • eng