Alzheimer disease with psychosis: excess cognitive impairment is restricted to the misidentification subtype.

Objective: Psychotic symptoms occur in 30%-60% of individuals with Alzheimer disease (AD) with psychosis (AD+P). AD+P identifies a distinct AD phenotype, with increased severity of cognitive impairment and a more rapid cognitive decline. Using factor and cluster analysis, we previously proposed two subtypes of patients with AD+P, one characterized by misidentifications and hallucinations (Misidentification), the other by persecutory delusions (Paranoid).

Psychotic symptoms in Alzheimer disease: evidence for subtypes.

Objective: Psychotic symptoms in Alzheimer disease (AD) identify a phenotype with distinct neurobiology and genetic architecture. The authors investigated whether AD with psychosis is homogeneous or is a composite of subtypes.

Methods: Authors performed factor and cluster analyses of the psychotic-symptom items of the CERAD Behavioral Rating Scale in 188 probable and possible AD subjects who have displayed at least one psychotic symptom.