Frailty is associated with incident Alzheimer's disease and cognitive decline in the elderly

Objective: To assess the association between frailty and incident Alzheimer's disease (AD) and cognitive decline. Frailty is common in older persons and associated with adverse health outcomes. Methods: Study subjects included 823 older persons without dementia who participated in the Rush Memory and Aging Project, a longitudinal study of aging, and underwent annual assessments of frailty, cognition, and diagnostic evaluation for AD. Results: During a 3-year follow-up, 89 of 823 participants developed AD. In a proportional hazards model, both baseline level of frailty and annual rate of change in frailty were associated with an increased risk of incident AD. Each additional one tenth of a unit increase on the frailty scale at baseline was associated with > 9% increased risk of AD (hazard ratio: 2.44; 95% confidence interval (CI): 1.49, 3.37); each one tenth of a unit increase in annual rate of change in frailty was associated with a 12% increased risk of AD (hazard ratio: 3.30; 95% CI: 1.52, 7.13). These results were unchanged in analyses controlling for vascular risk factors and vascular diseases. Results were similar with a categorical measure of frailty instead of a continuous measure. Further, linear mixed-effects models showed that the level of and rate of change in frailty were also associated with the rate of cognitive decline. Conclusion: Increasing frailty is associated with incident AD and the rate of cognitive decline in older persons. These findings suggest that frailty and AD may share similar etiologies.