title: Dorsolateral prefrontal hemodynamic responses during a verbal fluency task in hypomanic bipolar disorder.
abstract: OBJECTIVE
  Neuroimaging studies have suggested prefrontal dysfunction in response to cognitive activation in bipolar disorder (BD). However, its characteristics in manic states have not been well understood. Thus, we compared prefrontal hemodynamic responses during a cognitive task between hypomanic and depressive states in BD. We then longitudinally compared hypomanic and subsequent euthymic states.
  
  
  METHODS
  The prefrontal function of 27 patients with BD (11 hypomanic and 16 depressed) and 12 age- and gender-matched healthy controls (HCs) was evaluated using near-infrared spectroscopy (NIRS) during a verbal fluency task (VFT). Hypomanic symptoms were assessed using the Young Mania Rating Scale. Among the 11 hypomanic patients, eight participated in the second NIRS measurement after their hypomanic symptoms resolved.
  
  
  RESULTS
  VFT performance did not differ among hypomanic, depressed, and HC groups. Both BD groups exhibited significantly lower activation during the VFT than HCs in the broader bilateral prefrontal cortex. Hemodynamic changes in the left dorsolateral prefrontal cortex (DLPFC) in the hypomanic patients with BD were significantly larger than those in the depressed patients. In addition, hypomanic symptom severity was positively correlated with activation in the left DLPFC and frontopolar cortex in patients with BD. Follow-up measurement of the hypomanic patients revealed that prefrontal activation was decreased after hypomanic symptoms resolved.
  
  
  CONCLUSIONS
  Combining cross-sectional and longitudinal assessments, the present results suggest that prefrontal hemodynamic responses associated with cognitive activation differ between hypomanic and depressive states in BD. NIRS measurement could be a useful tool for objectively evaluating state-dependent characteristics of prefrontal hemodynamics in BD.
authors.affiliation: Department of Clinical Laboratory, Tokyo Metropolitan Matsuzawa Hospital, Setagaya-ku, Tokyo; Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo.
authors.forename: Yukika
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Takahashi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohtani
authors.forename: Reina
authors.initials: R
authors.lastname: Ikeda-Sugita
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
authors.forename: Yuji
authors.initials: Y
authors.lastname: Okazaki
mesh_terms: D000328:Adult; D018692:Antimanic Agents / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology; D002560:Cerebrovascular Circulation; D003430:Cross-Sectional Studies; D003863:Depression / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D059907:Functional Neuroimaging; D006439:Hemodynamics; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000098:blood supply* / Q000503:physiopathology; D019265:Spectroscopy, Near-Infrared
chemical_list: D018692:Antimanic Agents
keywords: bipolar disorder; executive function; hypomanic symptoms; near-infrared spectroscopy (NIRS); prefrontal cortex