title: Differential working memory performance as support for the Kraepelinian dichotomy between schizophrenia and bipolar disorder? An experimental neuropsychological study using circuit-specific working memory tasks.
abstract: OBJECTIVE
  The traditional clinical dichotomy of schizophrenia and bipolar disorder has been challenged by recent findings of an at least in part common genetic basis. The investigation of neurocognitive functions like working memory may thereby contribute to elucidate common versus distinct pathophysiological processes of the major psychoses. To date direct comparisons of working memory functioning in schizophrenia and bipolar disorder have been rare and moreover have revealed inconsistent findings. In this study we aimed to further clarify the diagnostic specificity of working memory deficits in schizophrenia and bipolar disorder.
  
  
  METHODS
  Fifty patients with schizophrenia, 23 patients with bipolar disorder and 53 healthy controls were tested with regard to specific dysfunctions of verbal and visuospatial working memory components using a set of well-characterized, brain circuit-specific paradigms with established brain-behaviour relationships.
  
  
  RESULTS
  Patients with schizophrenia showed marked deficits across different working memory domains while bipolar patients performed intermediate with no significant differences compared to the control group. Working memory performance of patients with schizophrenia and bipolar disorder significantly differed in only one particular task requiring articulatory rehearsal of verbal information.
  
  
  CONCLUSIONS
  While these results do not provide unequivocal support for the Kraepelinian dichotomy, they are consistent with recent findings suggesting the existence of a specific subgroup of schizophrenia patients phenotypically characterized by selective deficits of the articulatory rehearsal mechanism of verbal working memory.
authors: Center for Translational Research in Systems Neuroscience and Psychiatry, Department of Psychiatry, University Medical Centre, Georg August University, Goettingen, Germany.
authors: David
authors: D
authors: Zilles
authors: Raphael
authors: R
authors: Jung
authors: Eva
authors: E
authors: Gruber
authors: Peter
authors: P
authors: Falkai
authors: Oliver
authors: O
authors: Gruber
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000150:complications / Q000175:diagnosis / Q000523:psychology*; D016022:Case-Control Studies; D058068:Endophenotypes; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications / Q000175:diagnosis*; D012565:Schizophrenic Psychology; D012680:Sensitivity and Specificity; D055815:Young Adult