title: Persistent cognitive dysfunctions in bipolar I disorder and schizophrenic patients: a 3-year follow-up study.
abstract: BACKGROUND
  Neurocognitive impairment has consistently been considered a central and stable feature in schizophrenia. As this possibility has been far less studied in bipolar disorder, we aimed to prospectively investigate the stability and specificity of cognitive performance in bipolar disorder compared to schizophrenia.
  
  
  METHODS
  Fifteen DSM-IV bipolar type I patients and 15 schizophrenic patients were assessed twice with a comprehensive neuropsychological battery and the Positive and Negative Syndrome Scale over a 3-year follow-up. The cognitive performance of the groups was compared at baseline and 3 years later as a mean with that of 26 healthy volunteers. Endpoint and baseline assessments were also compared for each patient group in order to evaluate the stability of cognitive impairment.
  
  
  RESULTS
  At both time points, bipolar and schizophrenic patients showed significant deficits on most of the cognitive tasks compared to healthy subjects. Overall, the cross-sectional cognitive profile was similar for both patient groups. Moreover, after controlling for age and length of illness, the two groups' cognitive function did not differ over time in any test. With the exception of the Stroop color-word interference task, performance at baseline for each test but neither length of illness nor diagnostic category predicted the endpoint performance.
  
  
  CONCLUSIONS
  This preliminary study suggests that cognitive impairment is also mainly stable over time in bipolar I disorder and thus not specific to schizophrenia.
authors.affiliation: Psychiatry Service, University Hospital Doctor Peset, Valencia, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Balanzá-Martínez
authors.forename: Rafael
authors.initials: R
authors.lastname: Tabarés-Seisdedos
authors.forename: Gabriel
authors.initials: G
authors.lastname: Selva-Vera
authors.forename: Anabel
authors.initials: A
authors.lastname: Martínez-Arán
authors.forename: Carla
authors.initials: C
authors.lastname: Torrent
authors.forename: José
authors.initials: J
authors.lastname: Salazar-Fraile
authors.forename: Carmen
authors.initials: C
authors.lastname: Leal-Cercós
authors.forename: Eduard
authors.initials: E
authors.lastname: Vieta
authors.forename: Manuel
authors.initials: M
authors.lastname: Gómez-Beneyto
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000150:complications* / Q000523:psychology*; D003072:Cognition Disorders / Q000209:etiology* / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011379:Prognosis; D012559:Schizophrenia / Q000150:complications*; D013997:Time Factors