title: Neuropsychological functions in patients with bipolar I and bipolar II disorder.
abstract: The literature reports persistent cognitive impairments in patients with bipolar disorder even after prolonged remission. However, a majority of studies have focused only on bipolar I disorder (BP-I), primarily because bipolar II disorder (BP-II) is often underdiagnosed or misdiagnosed. More attention should be paid to the differences between BP-I and BP-II, especially the aspects of neuropsychological functioning. We examined the different neuropsychological functions in BP-I and BP-II patients and compared them with those of healthy controls.
  
  
  METHODS
  The study included 67 patients with interepisode bipolar disorder (BP-I: n = 30; BP-II: n = 37) and 22 healthy controls compared using a battery of neuropsychological tests that assessed memory, psychomotor speed, and certain aspects of frontal executive function.
  
  
  RESULTS
  The BP-I group performed poorly on verbal memory, psychomotor speed, and executive function compared to the BP-II and control groups. Both bipolar groups performed significantly less well than the control group on measures of working memory and psychomotor speed, while the BP-II group showed an intermediate level of performance in psychomotor speed compared to the BP-I and control groups. There was no difference between the groups on visual memory.
  
  
  CONCLUSIONS
  BP-I was characterized by reduced performance in verbal memory, working memory, psychomotor speed, and executive function, while BP-II patients showed a reduction only in working memory and psychomotor speed. Cognitive impairment existed in both subtypes of bipolar disorder, and was greater in BP-I patients. Rehabilitation interventions should take into account potential cognitive differences between these bipolar subtypes.
authors.affiliation: Institute of Behavioral Medicine, National Cheng Kung University Hospital, 138 Sheng-Li Road, Tainan 70428, Taiwan, ROC.
authors.forename: Yih-Lynn
authors.initials: YL
authors.lastname: Hsiao
authors.forename: Yi-Syuan
authors.initials: YS
authors.lastname: Wu
authors.forename: Jo Yung-Wei
authors.initials: JY
authors.lastname: Wu
authors.forename: Min-Hsien
authors.initials: MH
authors.lastname: Hsu
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Chen
authors.forename: Sheng-Yu
authors.initials: SY
authors.lastname: Lee
authors.forename: I-Hui
authors.initials: IH
authors.lastname: Lee
authors.forename: Tzung-Lieh
authors.initials: TL
authors.lastname: Yeh
authors.forename: Yen-Kuang
authors.initials: YK
authors.lastname: Yang
authors.forename: Huei-Chen
authors.initials: HC
authors.lastname: Ko
authors.forename: Ru-Band
authors.initials: RB
authors.lastname: Lu
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D001714:Bipolar Disorder / Q000145:classification* / Q000150:complications*; D003072:Cognition Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D011340:Problem Solving / Q000502:physiology; D055815:Young Adult