title: Course of subthreshold bipolar disorder in youth: diagnostic progression from bipolar disorder not otherwise specified.
abstract: OBJECTIVE
  To determine the rate of diagnostic conversion from an operationalized diagnosis of bipolar disorder not otherwise specified (BP-NOS) to bipolar I disorder (BP-I) or bipolar II disorder (BP-II) in youth over prospective follow-up and to identify factors associated with conversion.
  
  
  METHODS
  Subjects were 140 children and adolescents recruited from clinical referrals or advertisement who met operationalized criteria for BP-NOS at intake and participated in at least one follow-up evaluation (91% of initial cohort). Diagnoses were assessed at follow-up interviews using the Longitudinal Interval Follow-Up Evaluation. The mean duration of follow-up was 5 years and the mean interval between assessments was 8.2 months.
  
  
  RESULTS
  Diagnostic conversion to BP-I or BP-II occurred in 63 subjects (45%): 32 (23%) to BP-I (nine of whom had initially converted to BP-II) and 31 to only BP-II (22%). Median time from intake to conversion was 58 weeks. First- or second-degree family history of mania or hypomania was the strongest baseline predictor of diagnostic conversion (p = .006). Over follow-up, conversion was associated with greater intensity of hypomanic symptoms and with greater exposure to specialized, intensive outpatient psychosocial treatments. There was no association between conversion and exposure to treatment with particular medication classes.
  
  
  CONCLUSIONS
  Children and adolescents referred with mood symptoms that meet operationalized criteria for BP-NOS, particularly those with a family history of BP, frequently progress to BP-I or BP-II. Efforts to identify these youth and effectively intervene may have the potential to curtail the progression of mood disorders in this high-risk population.
authors.affiliation: University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, Pittsburgh, PA 15213, USA. axelsonda@upmc.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Axelson
authors.forename: Boris
authors.initials: B
authors.lastname: Birmaher
authors.forename: Michael A
authors.initials: MA
authors.lastname: Strober
authors.forename: Benjamin I
authors.initials: BI
authors.lastname: Goldstein
authors.forename: Wonho
authors.initials: W
authors.lastname: Ha
authors.forename: Mary Kay
authors.initials: MK
authors.lastname: Gill
authors.forename: Tina R
authors.initials: TR
authors.lastname: Goldstein
authors.forename: Shirley
authors.initials: S
authors.lastname: Yen
authors.forename: Heather
authors.initials: H
authors.lastname: Hower
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Hunt
authors.forename: Fangzi
authors.initials: F
authors.lastname: Liao
authors.forename: Satish
authors.initials: S
authors.lastname: Iyengar
authors.forename: Daniel
authors.initials: D
authors.lastname: Dickstein
authors.forename: Eunice
authors.initials: E
authors.lastname: Kim
authors.forename: Neal D
authors.initials: ND
authors.lastname: Ryan
authors.forename: Erica
authors.initials: E
authors.lastname: Frankel
authors.forename: Martin B
authors.initials: MB
authors.lastname: Keller
mesh_terms: D000293:Adolescent; D001714:Bipolar Disorder / Q000145:classification* / Q000175:diagnosis* / Q000628:therapy; D002648:Child; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D012307:Risk Factors; D012720:Severity of Illness Index