title: Thought disorder, pragmatic language impairment, and generalized cognitive decline in schizophrenia.
abstract: BACKGROUND
  Schizophrenia is associated with pragmatic language impairment (PLI), a reduced ability to communicate intention in a rule-governed fashion. Two explanations for PLI include that PLI is equivalent to thought disorder and that PLI is secondary to generalized cognitive decline.
  
  
  OBJECTIVE
  The aims of this study were to demonstrate PLI in schizophrenia and to test which of these explanations best accounts for the relationships among thought disorder, PLI, and generalized cognitive decline.
  
  
  METHODS
  Schizophrenia (n=20) and control (n=26) participants provided speech samples that were scored for thought disorder (type-token ratio and Cloze procedure) and PLI [Profile of Pragmatic Impairment in Communication (PPIC)]. Generalized cognitive decline was determined from discrepancies between current and premorbid verbal IQ.
  
  
  RESULTS
  Patients with schizophrenia exhibited significant PLI and generalized cognitive decline. There was no evidence of an association between thought disorder and PLI. Moreover, generalized cognitive decline predicted PLI (r(2)=0.33 to 0.59) but not thought disorder (r(2)=0.02 to 0.06).
  
  
  CONCLUSIONS
  The results conformed to a predicted pattern of associations based on the notion that PLI in schizophrenia is secondary to generalized cognitive decline.
authors.affiliation: Department of Psychology, University of Otago, P. O. Box 56, Dunedin, New Zealand. linscott@psy.otago.ac.nz
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Linscott
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000175:diagnosis / Q000209:etiology*; D007807:Language Tests; D008297:Male; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications*; D012720:Severity of Illness Index; D013850:Thinking