Neuropsychological functions in patients with bipolar I and bipolar II disorder

Yih Lynn Hsiao, Yi Syuan Wu, Jo Yung Wei Wu, Min Hsien Hsu, Hui Chun Chen, Sheng Yu Lee, I. Hui Lee, Tzung Lieh Yeh, Yen Kuang Yang, Huei Chen Ko, Ru Band Lu

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)


Objectives: 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. Mehods: 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.

Original languageEnglish
Pages (from-to)547-554
Number of pages8
JournalBipolar Disorders
Issue number5
Publication statusPublished - 2009

All Science Journal Classification (ASJC) codes

  • Psychiatry and Mental health
  • Biological Psychiatry


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