Psychological well-being mediates the association between physical frailty and cognitive impairment among Chinese older adults

BACKGROUND: Physical frailty is a well-established risk factor for cognitive impairment, but the psychosocial mechanisms underlying this link remain insufficiently understood. Psychological well-being (PWB) may represent a modifiable pathway. This study examined whether PWB mediates the association between physical frailty and incident cognitive impairment, and whether this pathway varies by age or gender. METHODS: We analyzed data from 11,607 cognitively normal adults aged ≥60 years in the Chinese Longitudinal Healthy Longevity Survey (CLHLS, 2008-2018). Frailty was assessed using a deficit-based Frailty Index, PWB using validated multi-item scales, and cognition using the Mini-Mental State Examination. Associations were examined using correlation, multivariable regression, and survival analyses. Causal mediation analysis under a counterfactual framework with 1,000 bootstrap resamples estimated direct and indirect effects, with age- and gender-stratified analyses assessing moderated mediation. RESULTS: Over a median follow-up of 40.3 months, 19.5% of participants developed cognitive impairment. Frailty was associated with a 40% higher hazard of cognitive impairment (HR=1.40, 95%CI: 1.15-1.71), and PWB mediated 6.5% of this association. The proportion mediated was greatest among adults aged 60-79 years (10.8%) and was not modified by gender. CONCLUSIONS: PWB partially mediates the frailty-cognition association in Chinese older adults, with stronger mediation observed in younger age groups. Enhancing psychological well-being may offer a scalable and modifiable strategy to strengthen cognitive resilience in rapidly ageing societies.