title: Component analysis of verbal fluency in patients with schizophrenia.
abstract: OBJECTIVE
  Clustering and-switching components of phonemic fluency performance were compared in patients with schizophrenia and healthy normal controls.
  
  
  BACKGROUND
  These components were selected to provide evidence for a specific anatomic locus for the breakdown of language processes or for a multiple-disease model of schizophrenia.
  
  
  METHODS
  As part of a larger battery of neuropsychological tests, phonemic fluency tests were administered on an individual basis. On separate 60-second trials, participants were instructed to generate words beginning with the letters C, F, and L, excluding proper names and variants of the same word. Three scores were obtained for each participant: (1) number of words generated, excluding errors and repetitions; (2) mean cluster size; and (3) raw number of switches.
  
  
  RESULTS
  The patients showed small but significant impairments in clustering and larger impairments in switching relative to normal controls.
  
  
  CONCLUSIONS
  This pattern suggests a relatively greater deficit in functioning in the frontal lobe than in the temporal lobe. However, neither measure was able to completely discriminate patients with schizophrenia from controls. Moreover, differences in fluency performance were observed among subtypes of schizophrenia. Taken together, the findings of impaired performance for both aspects of fluency, differences between subtypes, and the failure to completely discriminate patients with schizophrenia from controls indicate that there is not a single marker of the disease, at least among these fluency variables. Instead, the current findings are more supportive of a multiple-disease model of schizophrenia.
authors.affiliation: Division of Life Sciences (Psychology), University of Toronto at Scarborough, Ontario, Canada. zakzanis@scar.utoronto.ca
authors.forename: K K
authors.initials: KK
authors.lastname: Zakzanis
authors.forename: A K
authors.initials: AK
authors.lastname: Troyer
authors.forename: J B
authors.initials: JB
authors.lastname: Rich
authors.forename: W
authors.initials: W
authors.lastname: Heinrichs
mesh_terms: D000328:Adult; D017677:Age Distribution; D000704:Analysis of Variance; D004522:Educational Status; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D012559:Schizophrenia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D017678:Sex Distribution; D013064:Speech Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*; D013702:Temporal Lobe / Q000503:physiopathology