title: Thought disorder in schizophrenia is associated with both executive dysfunction and circumscribed impairments in semantic function.
abstract: BACKGROUND
  Formal thought disorder (FTD) has long been regarded as a key sign of schizophrenia but little is known about its origins or aetiology. One suggestion is that it is directly related to disordered language functioning; a second is that it is a reflection of poor neurocognitive functioning. A current model posits that it is related to a combination of executive dysfunction and impaired semantic processing.
  
  
  METHODS
  To examine these alternative ideas, a heterogeneous group of 30 patients, all carrying a diagnosis of schizophrenia, and 18 non-patient controls completed a series of neurocognitive and psycholinguistic tests, and a clinical review that, inter alia, permitted assessment of thought disorder (TD) using the Thought, Language and Communication Scale (TLC).
  
  
  RESULTS
  Patients generally performed at a lower level on most components of the test battery, but there was little evidence of a relationship between TD and syntactic psycholinguistic function. However, schizophrenic patients manifesting higher levels of TD performed at a lower level on tests sensitive to executive dysfunction and semantic impairments.
  
  
  CONCLUSIONS
  The origins of TD seem more closely linked to deficits in executive functioning and semantic processing than to impairments in other language functions or general cognition.
authors.affiliation: Department of Psychology and Speech Pathology, Manchester Metropolitan University, Manchester, UK. j.stirling@mmu.ac.uk
authors.forename: John
authors.initials: J
authors.lastname: Stirling
authors.forename: Jonathan
authors.initials: J
authors.lastname: Hellewell
authors.forename: Andrew
authors.initials: A
authors.lastname: Blakey
authors.forename: William
authors.initials: W
authors.lastname: Deakin
mesh_terms: D000293:Adolescent; D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000453:epidemiology*; D012660:Semantics; D012720:Severity of Illness Index; D013850:Thinking