title: The relationship of excess cognitive impairment in MCI and early Alzheimer's disease to the subsequent emergence of psychosis.
abstract: BACKGROUND
  Psychotic symptoms in Alzheimer disease (AD + P) identify a heritable phenotype associated with greater cognitive impairment. Knowing when the cognitive course of AD + P subjects diverges from that of subjects without psychosis would enhance understanding of how genetic variation results in AD + P and its associated cognitive burden. This study seeks to determine whether the degree of cognitive impairment and cognitive decline in early AD predicts subsequent AD + P onset.
  
  
  METHODS
  361 subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis were evaluated every 6 months until psychosis onset.
  
  
  RESULTS
  Severity of cognitive dysfunction was a strong predictor of AD + P up to two years prior to psychosis onset. Cognition did not decline more rapidly prior to onset of AD + P.
  
  
  CONCLUSIONS
  Individuals who will develop AD + P already demonstrate excess cognitive impairment during the mild stages of disease. Genetic variation and brain pathophysiology may lead to a cognitive risk phenotype which is present prior to dementia onset.
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Pittsburgh, USA.
authors.forename: Elise A
authors.initials: EA
authors.lastname: Weamer
authors.forename: James E
authors.initials: JE
authors.lastname: Emanuel
authors.forename: Daniel
authors.initials: D
authors.lastname: Varon
authors.forename: Sachiko
authors.initials: S
authors.lastname: Miyahara
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Wilkosz
authors.forename: Oscar L
authors.initials: OL
authors.lastname: Lopez
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* / Q000453:epidemiology / Q000235:genetics; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010414:Pennsylvania; D010641:Phenotype; D011594:Psychometrics; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D012307:Risk Factors