title: Differentiation between major depressive disorder and bipolar disorder by auditory steady-state responses.
abstract: BACKGROUND
  The auditory steady-state response (ASSR) elicited by gamma band neural oscillations has received considerable interest as a biomarker of psychiatric disorders. Although recent ASSR studies have reported that patients with bipolar disorder (BD) show altered ASSRs, little is known about ASSRs in patients with major depressive disorder (MDD). The aim of this study was to evaluate whether ASSRs in MDD subjects differed from those in BD subjects or normal controls (NC).
  
  
  METHODS
  We analyzed ASSRs in 14 MDD patients, 19 BD patients, and 29 normal control subjects. We used whole-head 306-channel magnetoencephalography to evaluate ASSR power and phase-locking factors (PLF) elicited by 20-, 30-, 40-, and 80-Hz click trains. We determined optimal sensitivity and specificity of ASSR power and PLF for the diagnosis of MDD or BD via receiver operating characteristic (ROC) curve analysis using a nonparametric approach.
  
  
  RESULTS
  MDD patients exhibited no significant differences in ASSR power or PLF compared with NC subjects, while BD patients showed deficits on the ASSR measures. MDD patients showed significantly larger ASSR power and PLF for 30-, 40-, and 80-Hz stimuli compared with BD patients. The area under the curve (AUC) for the ROC analysis (MDD vs. BD) was 0.81 [95% CI=0.66-0.96, p=0.003] concerning 40-Hz ASSR power.
  
  
  CONCLUSIONS
  We could not exclude the effect of medication and the sample size of the current study is relatively small.
  
  
  CONCLUSIONS
  We could differentiate between MDD and BD subjects in terms of gamma band ASSR. Our data suggest that the 40-Hz ASSR may be a potential biomarker for differentiation between MDD and BD patients.
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Isomura
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: toshiaki@npsych.med.kyushu-u.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Onitsuka
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Fukuoka Prefectural Psychiatric Center, Dazaifu Hospital, Dazaifu, Japan.
authors.forename: Rikako
authors.initials: R
authors.lastname: Tsuchimoto
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Itta
authors.initials: I
authors.lastname: Nakamura
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Neural Dynamics Laboratory, Research Service, Veterans Affairs Boston Healthcare System, and Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
authors.forename: Shogo
authors.initials: S
authors.lastname: Hirano
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Oda
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Division of Clinical Research, National Hospital Organization, Hizen Psychiatric Center, Saga, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Oribe
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Neural Dynamics Laboratory, Research Service, Veterans Affairs Boston Healthcare System, and Department of Psychiatry, Harvard Medical School, Boston, MA, USA; Division of Clinical Research, National Hospital Organization, Hizen Psychiatric Center, Saga, Japan.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Hirano
authors.affiliation: Division of Clinical Research, National Hospital Organization, Hizen Psychiatric Center, Saga, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Ueno
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Kanba
mesh_terms: D000328:Adult; D015415:Biomarkers; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000503:physiopathology*; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000503:physiopathology*; D003937:Diagnosis, Differential; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: Auditory steady-state response; Biomarker; Bipolar disorder; Gamma oscillation; Magnetoencephalography; Major depressive disorder