In a consecutive sample of 230 community-dwelling patients with probable
Alzheimer's disease, a structured interview yielded evidence of current
hallucinations in 29.1% and misperceptions in another 11.3%. Visual and
auditory modalities were similarly represented in apparent hallucinations.
Hallucinations prior to the current monitoring period were rare among
patients with misperceptions or with no perceptual abnormality. The
probability of hallucinations was associated with the severity of cognitive
dysfunction, the degree of other behavioral disturbances, and the presence
of extrapyramidal signs. A logistic regression model predicting
hallucinations based on these diverse clinical features accurately
classified 87.0% of the sample.