title: Working memory constrains abstraction in schizophrenia.
abstract: BACKGROUND
  Abstraction has long been considered an area of differential cognitive deficit in schizophrenia, primarily because of patients' poor performance on the Wisconsin Card Sorting Test (WCST). Yet, the complexity and multidimensional nature of the WCST increases the likelihood that several different cognitive processes, perhaps mediated by different neural systems, are being tapped.
  
  
  METHODS
  In the current study, the Abstraction and Working Memory (AIM) task was designed to disentangle abstraction and working memory so that the effects of each cognitive domain could be independently analyzed. The AIM task and a battery of neuropsychological tests were administered to 62 patients with schizophrenia and 62 matched healthy volunteers.
  
  
  RESULTS
  Whereas patients with schizophrenia demonstrated deficits in simple abstraction, they were disproportionately impaired with the addition of a minimal memory requirement.
  
  
  CONCLUSIONS
  Group differences on WCST performance appear to be attributable to patients' inability to maintain information over a short delay, before that information is used for more complex cognitive operations.
authors.affiliation: Department of Psychology, University of Pennsylvania, Philadelphia, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Glahn
authors.forename: T D
authors.initials: TD
authors.lastname: Cannon
authors.forename: R E
authors.initials: RE
authors.lastname: Gur
authors.forename: J D
authors.initials: JD
authors.lastname: Ragland
authors.forename: R C
authors.initials: RC
authors.lastname: Gur
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D011340:Problem Solving; D012565:Schizophrenic Psychology; D018709:Statistics, Nonparametric