Cognitive frailty and functional disability in older adults: A 10-year prospective cohort study in Japan

Cognitive frailty is considered a clinical entity associated with a high risk for adverse health outcomes. However, its clinical significance remains poorly understood. This study investigated the association between cognitive frailty and risk for functional disability among community-dwelling older adults. In total, 1,597 Japanese adults aged ≥ 65 years that were free of dementia and functional disability at baseline were prospectively followed for 10 years. Cognitive frailty was defined as the presence of both physical frailty (using Cardiovascular Health Study criteria) and cognitive impairment (Mini-Mental State Examination score < 26 points). Functional disability was identified using Japan's Long-term Care Insurance System database. Cox proportional hazard models were used to estimate the hazard ratios (HR) for cognitive frailty on the risk for functional disability. Functional disability was identified in 488 participants during follow-up. A multiplicative interaction effect between cognitive impairment and physical frailty on the risk of disability was observed (p = 0.045). Compared with the robust group, the multivariable-adjusted HRs (95% confidence interval) for functional disability were 3.70 (2.37‒5.77) for cognitive frailty, 2.51 (1.81‒3.47) for physical pre-frailty with cognitive impairment, 2.16 (1.42‒3.29) for cognitive impairment only, 1.95 (1.36‒2.80) for physical frailty only, and 1.94 (1.53‒2.46) for physical pre-frailty only. These associations remained after adjusting for the competing risk for death and in sensitivity analyses to minimize potential reverse causality. Cognitive frailty is associated with an increased risk for functional disability in community-dwelling older adults. Cognitive frailty may be a clinically important target for the prevention of functional disability.