Association between long-term ambient air pollution exposure and cognitive disorders among older adults in China: the mediating role of lifestyle

Background: Cognitive disorders (CDs) are a major public health concern in ageing societies. The association between air pollution and CDs has received considerable attention; however, the moderating role of lifestyle remains unclear. We aimed to explore the complex associations among lifestyle, its dynamic changes, ambient air pollution exposure, and CDs in older adults. Methods: We included data from the Chinese Longitudinal Healthy Longevity Study. We used Cox proportional hazards models, Bayesian weighted quantile sum models, and mediation analysis to explore associations between lifestyle, air pollution, and CDs risk. Results: increase in exposure to particulate matter with diameters ≤2.5 μm (hazard ratio (HR) = 1.005; 95% confidence interval (CI) = 1.001-1.009), sulphates (HR = 1.030; 95% CI = 1.003-1.056), ozone (HR = 1.006; 95% CI = 1.001-1.011), nitrates (HR = 1.020; 95% CI = 1.003-1.037), and ammonium (HR = 1.033; 95% CI = 1.005-1.062) was associated with an increased risk of CDs. The mixture exposure showed a significant positive association with CDs (odds ratio = 1.028; 95% CI = 1.006-1.040). Adherence to both intermediate (HR = 0.732; 95%CI = 0.569-0.940) and favourable (HR = 0.488; 95%CI = 0.336-0.710) lifestyles was associated with a reduced risk of CDs compared to an unfavourable lifestyle, and the protective effect was more significant at high pollution exposure levels (about 52% lower risk). Lifestyle mediated the effect by 8.4-9.4% in the association between single pollutants and CDs, and 9.1-9.5% in the association between mixed pollutants and CDs. Ozone had the highest weight in the pollution mixture. Conclusions: Air pollution increased the risk of CDs among older adults, which was partially offset by a healthy lifestyle. Lifestyle interventions may help address some challenges inherent in controlling air pollution in ageing societies.