Impact of Cognitive Frailty on Activities of Daily Living, Cognitive Function, and Conversion to Dementia Among Memory Clinic Patients with Mild Cognitive Impairment

Background: Very few studies have investigated the impact of cognitive frailty in clinical settings, especially in memory clinic populations. Objective: To examine the impact of cognitive frailty on activities of daily living (ADL), cognitive function, and conversion to dementia among memory clinic patients with mild cognitive impairment (MCI). Methods: The subjects of this retrospective study were 248 MCI patients (mean age, 76.3±5.4 years; females, 60.9%). All subjects completed a comprehensive geriatric assessment at baseline and at least one assessment during 3-year follow-up. Frailty was defined by generating a frailty index (FI), and MCI patients with frailty (FI≥0.25) were considered to represent cognitive frailty. As primary outcomes, the Barthel Index, Mini-Mental State Examination, and incident dementia were evaluated during follow-up. At baseline, patients were assessed for apolipoprotein E ( APOE) phenotype. A linear mixed model, as well as a Cox proportional hazards regression model with adjustment for confounding variables, was performed. Results: Of these patients, 75 (30.2%) were classified as cognitive frail. APOE ɛ4 carriers accounted for 26.7% of those with cognitive frailty and 44.5% of those without ( p = 0.008). Cognitive frail patients showed a faster ADL decline (estimate, –1.04; standard error, 0.38; p = 0.007) than patients without cognitive frailty. Cognitive frailty was not associated with cognitive decline and incident dementia. Conclusion: Our findings demonstrated cognitive frailty increases the risk of dependence but not cognitive outcomes. Cognitive frailty may have heterogeneous conditions, including APOE ɛ4-related pathologies, which may affect the cognitive trajectories of patients with MCI.