10-year frailty trajectory is associated with Alzheimer's dementia after considering neuropathological burden

Frailty is an established risk factor for cognitive decline and Alzheimer's disease. Few studies have examined the longitudinal relationship between frailty and cognition.

Participants of Rush Memory and Aging project (n = 625, 67.5% female, 83.2 ± 5.9 years at baseline) underwent annual clinical evaluations (average follow-up 5.6 ± 3.7 years) followed by neuropathologic assessment after death. A frailty index was calculated from 41 health variables at each evaluation. Clinical diagnosis of MCI and/or dementia was ascertained by clinical data review (blinded to neuropathological data) after death. Age, sex, education, and neuropathological burden (10-item index) were evaluated as covariates. Frailty trajectories were calculated using a mixed effects model.

At baseline the mean frailty index = 0.24 ± 0.12 and increased at rate of 0.026 or ~1 deficit per year. At death, 27.7% of the sample had MCI, and 38.6% had dementia. Frailty trajectories were significantly steeper among those individuals who were ultimately diagnosed as clinically impaired prior to death, even after controlling for age, sex, education, and neuropathological index.

Findings suggest a strong link between health status (frailty index) and dementia, even after considering neuropathology. Frailty trajectories were associated with risk for MCI and dementia, underscoring the importance of addressing frailty to manage dementia risk.