title: Detailed course of depressive symptoms and risk for developing depression in late adolescents with subthreshold depression: a cohort study.
abstract: OBJECTIVE
  Despite its clinical importance, adolescent subthreshold depression remains a largely neglected topic. The aims of this study were to accurately identify the natural course of depressive symptoms and the risk for developing major depressive episode (MDE) in late adolescents with subthreshold depression over 1 year.
  
  
  METHODS
  One hundred and seventy-two participants <20 years of age (mean age: 18.32 years, standard deviation: 0.50), who did not meet the full criteria for an MDE, were selected from 2,494 screened freshmen based on the Beck Depression Inventory, 2nd edition (BDI-II). We conducted a cohort study of three groups (low-, middle-, and high-symptom groups) divided based on BDI-II scores, over a 1 year period with the use of bimonthly assessments. Temporal changes of depressive symptoms were analyzed using linear mixed modeling and growth mixture modeling.
  
  
  RESULTS
  First, we found that late adolescents with subthreshold depression (high depressive symptoms) were split between the increasing and decreasing depressive symptoms groups, whereas the majority of the less-symptoms group remained stable during 1 year. Second, in comparison with late adolescents with less depressive symptoms, those with subthreshold depression had an elevated risk of later depression.
  
  
  CONCLUSIONS
  Some late adolescents with subthreshold depression had increased depressive symptoms and developed an MDE during 1 year. Therefore, it is necessary for us to rigorously assess the changes in subthreshold depressive symptoms over time in late adolescents.
authors.affiliation: Department of Psychiatry and Neurosciences.
authors.forename: Ran
authors.initials: R
authors.lastname: Jinnin
authors.affiliation: Department of Psychiatry and Neurosciences.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Department of Psychiatry and Neurosciences.
authors.forename: Koki
authors.initials: K
authors.lastname: Takagaki
authors.affiliation: Department of Psychiatry and Neurosciences.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Nishiyama
authors.affiliation: Department of Psychiatry and Neurosciences.
authors.forename: Takanao
authors.initials: T
authors.lastname: Yamamura
authors.affiliation: Health Service Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Health Service Center, Hiroshima University, Hiroshima, Japan.
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Miyake
authors.affiliation: Risk Analysis Research Center, The Institute of Statistical Mathematics, Tokyo, Japan.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Takebayashi
authors.affiliation: Graduate School of Education, Joetsu University of Education, Niigata, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Sugiura
authors.affiliation: Department of Mental Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Shimoda
authors.affiliation: Department of Mental Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Norito
authors.initials: N
authors.lastname: Kawakami
authors.affiliation: Department of Health Promotion and Human Behavior, Kyoto University Graduate School of Medicine/School of Public Health, Kyoto, Japan.
authors.forename: Toshi A
authors.initials: TA
authors.lastname: Furukawa
authors.affiliation: Department of Psychiatry and Neurosciences.
authors.forename: Shigeto
authors.initials: S
authors.lastname: Yamawaki
keywords: adolescence; cohort study; major depressive episode; subthreshold depression; university student