Association between air pollution and the risk of cognitive frailty: insights from two population-based studies in the United Kingdom and China

BACKGROUND: Cognitive frailty, encompassing cognitive decline and physical frailty, is an increasing concern in aging populations. Air pollution is associated to several health outcomes. METHODS: Data of 62 098 participants from UK Biobank cohort and 3321 participants from West China Health and Aging Trend (WCHAT) cohort were subjected to cross-sectional analyses to evaluate the association between the investigating parameters, and prospective analyses were performed in the UK Biobank. RESULTS: Exposure to ambient air pollution was significantly associated with increased risk of cognitive frailty in middle-aged and older adults. In the UK Biobank prospective analysis, exposures to NOx (hazard ratio [HR] 1.11, 95% confidence interval [CI], 1.01-1.23; p = .0357), nitrogen dioxide (HR 1.14, 95% CI, 1.00-1.30; p = .0428), and PM2.5 (HR 1.18, 95% CI, 1.04-1.34; p = .0091) were consistently associated with cognitive frailty. Cross-sectional analyses in the UK Biobank supported these findings, with additional positive associations observed for PM10 (odds ratio [OR] 1.02, 95% CI, 1.00-1.05; p = .0374). In WCHAT cohort, ozone exposure showed the most consistent associations across exposure windows and models (3-year: OR 1.29, 95% CI, 1.14-1.45; p < .0001; 5-year: OR 1.34, 95% CI, 1.20-1.50; p < .0001). Additionally, PM2.5 exposure within the 1-year exposure window also demonstrated a statistically significant association (Q3: OR 1.53, 95% CI, 1.04-2.25; p = .0327). Stratified analyses suggested stronger associations among adults ≥60 years, females, and overweight individuals. CONCLUSIONS: Higher air pollution levels were significantly associated with increased cognitive frailty risk, emphasizing on developing public health interventions to reduce air pollution exposure, especially among vulnerable populations.