title: Preserved, deteriorated, and premorbidly impaired patterns of intellectual ability in schizophrenia.
abstract: OBJECTIVE
  The main purpose of this investigation was to identify patterns of intellectual performance in schizophrenia patients suggesting preserved, deteriorated, and premorbidly impaired ability, and to determine clinical, cognitive, and functional correlates of these patterns.
  
  
  METHODS
  We assessed 101 patients with schizophrenia or schizoaffective disorder and 80 non-psychiatric control participants. The "preserved" performance pattern was defined by average-range estimated premorbid and current IQ with no evidence of decline (premorbid-current IQ difference <10 points). The "deteriorated" pattern was defined by a difference between estimated premorbid and current IQ estimates of 10 points or more. The premorbidly "impaired" pattern was defined by below average estimated premorbid and current IQ and no evidence of decline greater than 10 points. Preserved and deteriorated patterns in healthy controls were also identified and studied in comparison to patient findings. The groups were compared on demographic, neurocognitive, clinical and functionality variables.
  
  
  RESULTS
  Patients with the preserved pattern outperformed those meeting criteria for deteriorated and compromised intellectual ability on a composite measure of neurocognitive ability as well as in terms of functional competence. Patients demonstrating the deteriorated and compromised patterns were equivalent across all measures. However, "preserved" patients failed to show any advantage in terms of community functioning and demonstrated cognitive impairments relative to control participants.
  
  
  CONCLUSIONS
  Our results suggest that proposed patterns of intellectual decline and stability exist in both the schizophrenia and general populations, but may not hold true across other cognitive abilities and do not translate into differential functional outcome.
authors.affiliation: Department of Psychology, York University.
authors.forename: Narmeen
authors.initials: N
authors.lastname: Ammari
authors.affiliation: Department of Psychology, York University.
authors.forename: R Walter
authors.initials: RW
authors.lastname: Heinrichs
authors.affiliation: Department of Psychology, York University.
authors.forename: Farena
authors.initials: F
authors.lastname: Pinnock
authors.affiliation: Department of Psychology, York University.
authors.forename: Ashley A
authors.initials: AA
authors.lastname: Miles
authors.affiliation: Department of Psychology, York University.
authors.forename: Eva
authors.initials: E
authors.lastname: Muharib
authors.affiliation: Department of Psychology, McMaster University.
authors.forename: Stephanie
authors.initials: S
authors.lastname: McDermid Vaz
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D057187:Independent Living / Q000523:psychology; D008607:Intellectual Disability / Q000209:etiology*; D007361:Intelligence Tests; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011618:Psychotic Disorders / Q000150:complications*; D012559:Schizophrenia / Q000150:complications*; D012565:Schizophrenic Psychology; D012919:Social Behavior; D055815:Young Adult