title: Escalation to Major Depressive Disorder among adolescents with subthreshold depressive symptoms: evidence of distinct subgroups at risk.
abstract: BACKGROUND
  The presence of subthreshold depressive symptoms (SubD) in adolescence is associated with high prospective risk of developing Major Depressive Disorder (MDD). Little is known about variables that predict escalation from SubD to MDD. This study used a longitudinal prospective design in a community sample of adolescents to identify combinations of risk factors that predicted escalation from SubD to MDD.
  
  
  METHODS
  Classification tree analysis was used to identify combinations of risk factors that improved the sensitivity and specificity of prediction of MDD onset among 424 adolescents with a lifetime history of SubD.
  
  
  RESULTS
  Of the 424, 144 developed MDD during the follow-up period. Evidence for multiple subgroups was found: among adolescents with poor friend support, the highest risk of escalation was among participants with lifetime histories of an anxiety or substance use disorder. Among adolescents with high friend support, those reporting multiple major life events in the past year or with a history of an anxiety disorder were at highest risk of escalation.
  
  
  CONCLUSIONS
  Study findings may not inform prevention efforts for individuals who first develop SubD during adulthood. This study did not examine the temporal ordering of predictors involved in escalation from SubD to MDD.
  
  
  CONCLUSIONS
  Adolescents with a history of SubD were at highest risk of escalation to MDD in the presence of poor friend support and an anxiety or substance use disorder, or in the presence of better friend support, multiple major life events, and an anxiety disorder. Findings may inform case identification approaches for adolescent depression prevention programs.
authors.affiliation: Florida International University, United States. Electronic address: rhill004@fiu.edu.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Hill
authors.affiliation: Florida International University, United States.
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Pettit
authors.affiliation: Oregon Research Institute, United States.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Lewinsohn
authors.affiliation: Oregon Research Institute, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Seeley
authors.affiliation: Stony Brook University, United States.
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Klein
mesh_terms: D000293:Adolescent; D001008:Anxiety Disorders / Q000523:psychology; D003863:Depression / Q000523:psychology*; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D033062:Friends / Q000523:psychology; D006801:Humans; D007406:Interview, Psychological; D008016:Life Change Events; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D012944:Social Support; D019966:Substance-Related Disorders / Q000523:psychology
keywords: Adolescence; Depression; Onset; Subthreshold depression