Background. Recent studies indicate that behavioral symptoms may play a key role in decisions to institutionalize persons with Alzheimer's disease (AD), but the specific types of behavior that contribute to this increased risk have not been reliably identified. The relationship between behavioral symptoms and time to institutionalization was evaluated in a 4-year longitudinal study.

Method. A total of 410 persons with the clinical diagnosis of AD completed annual clinical evaluations to assess cognitive impairment, functional limitations, delusions, hallucinations, depressive symptoms and physical aggression. Participation rates among survivors exceeded 90% for four follow-up evaluations with complete ascertainment of mortality and institutionalization. Time to institutionalization was evaluated using proportional hazards regression models in relation to time-varying clinical features.

Results. In multivariate models, adjusted for demographic and social variables, four clinical features emerged as the predominant predictors of institutionalization: cognitive impairment level, physical aggression, hallucinations and depressive symptoms. These associations were virtually unchanged in analyses controlling for mortality.

Conclusions. Specific behavioral symptoms are important independent risk factors for institutionalization in persons with AD. Because behavioral symptoms are susceptible to therapy, efforts to modify or prevent these symptoms deserve careful consideration as a means to delay institutionalization for persons with this disease.