["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.", '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.', '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.'] Is frailty associated with incident Alzheimer 's disease and cognitive decline in the elderly?