Frailty and Cognition Transitions and the Development of Cognitive Frailty among Community-Living Older Adults in the Singapore Longitudinal Ageing Studies

Background: Studies of the natural progression and temporal co-occurrence of physical frailty and cognitive impairment are needed to validate the construct of cognitive frailty, a state of mild cognitive impairment caused by physical frailty. Method: We analysed data from Singapore Longitudinal Ageing Studies (SLAS-1 and SLAS-2) participants (N = 2554), free of functional disability, dementia, neurodegenerative diseases, and stroke, who were categorized at baseline as robust and cognitive normal (N = 1252), physically frail alone (N = 913), cognitively impaired alone (N = 197), and concurrently frail and cognitively impaired (N = 232) with average 5-years of follow up. Physical frailty was defined as pre-frailty/frailty (Fried criteria scores 1–5) and cognitive impairment MMSE scores <27 (age and education adjusted). Results: Among cognitively normal and robust participants, the occurrence of pre-frailty/frailty alone was 80.4%, cognitive impairment alone was 0.6%, and co-occurring pre-frailty/frailty and cognitive impairment (cognitive frailty) was 3.8%. Among cognitively normal and pre-frail/frail participants, the occurrence of cognitive frailty (5.9%) was significantly higher (OR = 1.53, 95% CI 1.02–2.28, adjusted for sex and age). Among cognitively normal and robust individuals, baseline number of comorbid medical comorbidities (OR = 1.37 (95% CI: 1.08–1.74) significantly predicted cognitive frailty. From following up a hypothetical cohort of 1000 robust and cognitively normal individuals, 88 of 91 outcome cases of co-occurring frailty and cognitive impairment were preceded by frailty alone (N = 48), or concurrent frailty and cognitive impairment (N = 40); only 3 cases were preceded by cognitive impairment alone (not cognitive frailty).Conclusions: The validity of cognitive frailty as a construct of mild cognitive impairment due to physical frailty is supported.