Psychotic symptoms in Alzheimer's disease

Memory loss is the hallmark of Alzheimer's disease. However, psychotic symptoms have also been reported. We studied the prevalence of hallucinations and delusions in 677 subjects with probable Alzheimer's disease. Data were collected in six centers and analyzed retrospectively. A two-stage, multivariate approach was used. The overall prevalence of these psychotic symptoms was 31%. The prevalence of hallucinations was 17%, and of delusions 26%. Both were associated with emotional incontinence, insomnia and agitation as well as with advanced disease. While psychotic symptoms were more prevalent in advanced disease, nonetheless they occurred with notable frequency in early disease. Of subjects with early AD (MMSE scores between 21 and 30), 6% had hallucinations and 17% had delusions. Alzheimer's disease must be considered in the differential diagnosis of any subject over 55 presenting with these psychotic symptoms.