Disentangling Cognitive-Frailty: Results From the Gait and Brain Study

Abstract

Background: Cognitive-frailty, defined as the presence of both frailty and cognitive impairment, is proposed as a distinctive entity that predicts dementia. However, it remains controversial whether frailty alone, cognitive-frailty, or the combination of cognitive impairment and slow gait pose different risks of incident dementia.

Methods: Two hundred and fifty-two older adults free of dementia at baseline (mean age 76.6±8.6 years) were followed up to 5 years with bi-annual visits including medical, cognitive, and gait assessments. Incident all-cause of dementia and cognitive decline were the main outcomes. Frailty was defined using validated phenotypic criteria. Cognition was assessed using the Montreal Cognitive Assessment while gait was assessed using an electronic walkway. Cox Proportional Hazards models were used to estimate the risk of cognitive decline and dementia for frailty, cognitive-frailty, and gait and cognition models.

Results: Fifty-three participants experienced cognitive decline and 27 progressed to dementia (incident rate: 73/1,000 person-years). Frailty participants had a higher prevalence of cognitive impairment compared with those without frailty (77% vs. 54%, p = .02) but not significant risk to incident dementia. Cognitive-frailty increased incident rate (80/1,000 person-years) but not risk for progression to dementia. The combination of slow gait and cognitive impairment posed the highest risk for progression to dementia (hazard ratio: 35.9, 95% confidence interval: 4.0-319.2; p = 0.001, incident rate: 130/1,000 person-years). None of the models explored significantly predicted cognitive decline.

Conclusions: Combining a simple motor test, such as gait velocity, with a reliable cognitive test like the Montreal Cognitive Assessment is superior than the cognitive-frailty construct to detect individuals at risk for dementia. Cognitive-frailty may embody two different manifestations, slow gait and low cognition, of a common underlying mechanism.

Keywords: Cognitive frailty; Dementia.; Frailty; Gait velocity.