title: Premorbid performance IQ deficit in schizophrenia.
abstract: OBJECTIVE
  Performance IQ (PIQ) is often lower than verbal IQ (VIQ) in schizophrenic patients. Whether PIQ < VIQ precedes psychotic symptoms in schizophrenia remains uncertain.
  
  
  METHODS
  We investigated premorbid IQ scores in 63 subjects assessed at a child and adolescent psychiatric unit (mean age 13.1 years, SD 3.2), who at follow-up in adulthood (mean age 30.9 years, SD 3.9) received a lifetime RDC diagnosis of schizophrenia-related psychosis, affective disorder, or no psychiatric disorder.
  
  
  RESULTS
  Premorbid PIQ < VIQ significantly differentiated the groups with schizophrenia-related psychosis and no psychiatric disorder. Subjects with schizophrenia-related psychosis had a significantly lower mean value for premorbid PIQ, but not VIQ, compared to subjects who developed affective disorder or subjects without psychiatric disorder.
  
  
  CONCLUSIONS
  Our results emphasize premorbid intellectual deficits in schizophrenia. Those deficits might largely be in consequence of an impairment on the PIQ scale.
authors.affiliation: University Hospital for Child and Adolescent Neuropsychiatry, Vienna, Austria.
authors.forename: G P
authors.initials: GP
authors.lastname: Amminger
authors.forename: M
authors.initials: M
authors.lastname: Schlögelhofer
authors.forename: T
authors.initials: T
authors.lastname: Lehner
authors.forename: S
authors.initials: S
authors.lastname: Looser Ott
authors.forename: M H
authors.initials: MH
authors.lastname: Friedrich
authors.forename: H N
authors.initials: HN
authors.lastname: Aschauer
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003072:Cognition Disorders / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007360:Intelligence; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D012565:Schizophrenic Psychology; D014705:Verbal Behavior