Psychiatric phenomena in Alzheimer's disease. II: Disorders of perception.

In a sample of 178 patients with AD, visual hallucinations had been experienced by 13% and auditory hallucinations by 10%. Thirty per cent had misidentification syndromes; these were associated with a younger age and younger age at onset of illness, and proportionally more men than women were affected. There was a reduced 30-month mortality rate in this group. Subjects with hallucinations had a greater deterioration in cognitive function at 12-month follow-up, which could not be accounted for by neuroleptic medication.