title: Differences between bipolar I and bipolar II disorders in clinical features, comorbidity, and family history.
abstract: BACKGROUND
  The present study was designed to investigate whether bipolar II disorder (BP-II) has different characteristics from bipolar I disorder (BP-I), not only in manic severity but also in clinical features, prior course, comorbidity, and family history, sufficiently enough to provide its nosological separation from BP-I.
  
  
  METHODS
  Comprehensive clinical evaluation was performed based on information available from ordinary clinical settings. Seventy-one BP-I and 34 BP-II patients were assessed using the Diagnostic Interview for Genetic Studies, Korean version. Psychiatric assessment for first-degree relatives (n=374) of the probands was performed using the modified version of the Family History-Research Diagnostic Criteria.
  
  
  RESULTS
  The frequency of depressive episodes was higher in BP-II (p=0.009) compared to BP-I. Further, seasonality (p=0.035) and rapid-cycling course (p=0.062) were more common in BP-II. Regarding manic expression, 'elated mood' was predominant in BP-II whereas 'elated mood' and 'irritable mood' were equally prevalent in BP-I. With regard to depressive symptoms, psychomotor agitation, guilty feeling, and suicidal ideation were more frequently observed in BP-II. BP-II patients exhibited a higher trend of lifetime co-occurrence of an axis I diagnosis (p=0.09), and a significantly higher incidence of phobia and eating disorder. The overall occurrence rate of psychiatric illness in first-degree relatives was 15.4% in BP-I and 26.5% in BP-II (p=0.01). Major depression (p=0.005) and substance-related disorder (p=0.051) were more prevalent in relatives of BP-II probands.
  
  
  CONCLUSIONS
  Distinctive characteristics of BP-II were identified in the current study and could be adopted to facilitate the differential diagnosis of BP-I and BP-II in ordinary clinical settings.
authors.affiliation: Department of Psychiatry, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Republic of Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Baek
authors.forename: Dong Yeon
authors.initials: DY
authors.lastname: Park
authors.forename: Jungmi
authors.initials: J
authors.lastname: Choi
authors.forename: Ji Sun
authors.initials: JS
authors.lastname: Kim
authors.forename: Ji Sun
authors.initials: JS
authors.lastname: Choi
authors.forename: Kyooseob
authors.initials: K
authors.lastname: Ha
authors.forename: Jun Soo
authors.initials: JS
authors.lastname: Kwon
authors.forename: Dongsoo
authors.initials: D
authors.lastname: Lee
authors.forename: Kyung Sue
authors.initials: KS
authors.lastname: Hong
mesh_terms: D000328:Adult; D000339:Affect; D001714:Bipolar Disorder / Q000145:classification* / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000523:psychology; D016009:Chi-Square Distribution; D015897:Comorbidity; D005190:Family / Q000523:psychology; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D016015:Logistic Models; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D011569:Psychiatric Status Rating Scales; D018709:Statistics, Nonparametric