Montero-Odasso MM, Barnes B, Speechley M, et al.
J Gerontol A Biol Sci Med Sci 2016; Mar 16 [Epub ahead of print]
Publication date: March 16, 2016
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.
In this study by Montero-Odasso et al., 252 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.
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=0.02) 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).
In conclusion, combining a simple motor test, such as gait velocity, with a reliable cognitive test like the Montreal Cognitive Assessment is superior to 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.