Abstract To clarify which baseline factors, including apolipoprotein E (ApoE) genotyping and caregiver characteristics, predict the future severity of behavioral disturbance among community-dwelling elderly with Alzheimer's disease (AD), we conducted a longitudinal study for up to 6 years. Fourteen kinds of behavioral disturbance were evaluated. Analyses using data from 62 subjects with at least three annual assessments revealed that the baseline severity of behavioral disturbance was the strongest predictor of future severity, followed by baseline stage of dementia or use of support services. However, ApoE ɛ4 had only a marginal effect at most. The behavioral disturbances examined in the present study appear to be innately determined phenomena rather than merely representing stages of AD.