title: Neurocognitive profiles in bipolar I and bipolar II disorder: differences in pattern and magnitude of dysfunction.
abstract: OBJECTIVE
  Studies on neurocognitive functioning in bipolar disorder, reporting deficits in memory, attention, and executive functioning, have primarily focused on bipolar I disorder. The aim of this study was to examine whether patients with bipolar I and bipolar II disorder have different neurocognitive profiles.
  
  
  METHODS
  Forty-two patients with bipolar I disorder, 31 patients with bipolar II and 124 healthy controls, from a large ongoing study on psychotic disorders, were included. Neurocognitive function was measured with a comprehensive neuropsychological test battery.
  
  
  RESULTS
  The bipolar I group performed significantly poorer than the healthy control group and the bipolar II group on all measures of memory. Compared with the control group, the bipolar I group also had significantly reduced performance on most measures of attention and executive functioning, while the bipolar II group only had a significantly reduced performance on a subset of these measures. On average, 24% of the bipolar I group had clinically significant cognitive impairment (< or =1.5 SD below the control group mean) across measures, compared with 13% of the bipolar II group.
  
  
  CONCLUSIONS
  Patients with bipolar I and bipolar II disorder in this study have different neurocognitive profiles. Bipolar I patients have more widespread cognitive dysfunction both in pattern and magnitude, and a higher proportion has clinically significant cognitive impairments compared with patients with bipolar II. This may suggest neurobiological differences between the two bipolar subgroups.
authors.affiliation: Department of Psychiatry, Ulleval University Hospital, and Institute of Psychology, University of Oslo, Oslo, Norway. c.e.simonsen@medisin.uio.no
authors.forename: Carmen
authors.initials: C
authors.lastname: Simonsen
authors.forename: Kjetil
authors.initials: K
authors.lastname: Sundet
authors.forename: Anja
authors.initials: A
authors.lastname: Vaskinn
authors.forename: Astrid B
authors.initials: AB
authors.lastname: Birkenaes
authors.forename: John A
authors.initials: JA
authors.lastname: Engh
authors.forename: Charlotte Fredslund
authors.initials: CF
authors.lastname: Hansen
authors.forename: Halldóra
authors.initials: H
authors.lastname: Jónsdóttir
authors.forename: Petter Andreas
authors.initials: PA
authors.lastname: Ringen
authors.forename: Stein
authors.initials: S
authors.lastname: Opjordsmoen
authors.forename: Svein
authors.initials: S
authors.lastname: Friis
authors.forename: Ole A
authors.initials: OA
authors.lastname: Andreassen
mesh_terms: D000328:Adult; D001288:Attention; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000453:epidemiology; D009483:Neuropsychological Tests; D015995:Prevalence; D012720:Severity of Illness Index; D014706:Verbal Learning