title: Psychotic symptoms in Alzheimer disease: evidence for subtypes.
abstract: 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.
  
  
  RESULTS
  Exploratory factor analysis resulted in a one-factor solution that comprised misidentification delusions, auditory and visual hallucinations, and the misidentification of people. Persecutory delusions were also frequently present and were independent of the misidentification/hallucination factor. Cluster analysis yielded similar results.
  
  
  CONCLUSIONS
  Misidentification/hallucinations and persecutory delusions may identify two subtypes of psychosis in AD. Longitudinal study is needed to determine whether these proposed subtypes remain stable and independent over time or merge into a single group over the course of illness.
authors.affiliation: Department of Psychiatry, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Cook
authors.forename: Sachiko
authors.initials: S
authors.lastname: Miyahara
authors.forename: Silviu-Alin
authors.initials: SA
authors.lastname: Bacanu
authors.forename: Gina
authors.initials: G
authors.lastname: Perez-Madriñan
authors.forename: Oscar L
authors.initials: OL
authors.lastname: Lopez
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Kaufer
authors.forename: Vishwajit L
authors.initials: VL
authors.lastname: Nimgaonkar
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Wisniewski
authors.forename: Steven T
authors.initials: ST
authors.lastname: DeKosky
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sweet
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology*; D016000:Cluster Analysis; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D010641:Phenotype; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000209:etiology*; D011795:Surveys and Questionnaires