Mental disorders are common, although reported rates differ according to developmental stage. 1 Costello EJ Copeland W Angold A Trends in psychopathology across the adolescent years: what changes when children become adolescents, and when adolescents become adults?. J Child Psychol Psychiatry. 2011; 52: 1015-1025 Crossref PubMed Scopus (484) Google Scholar The prevalence of common mental disorders such as depression increases in adolescence, 1 Costello EJ Copeland W Angold A Trends in psychopathology across the adolescent years: what changes when children become adolescents, and when adolescents become adults?. J Child Psychol Psychiatry. 2011; 52: 1015-1025 Crossref PubMed Scopus (484) Google Scholar , 2 Kim-Cohen J Caspi A Moffitt TE Harrington H Milne BJ Poulton R Prior juvenile diagnoses in adults with mental disorder: developmental follow-back of a prospective-longitudinal cohort. Arch Gen Psychiatry. 2003; 60: 709-717 Crossref PubMed Scopus (1476) Google Scholar and many people will experience such a disorder by young adulthood. 3 Copeland W Shanahan L Costello EJ Angold A Cumulative prevalence of psychiatric disorders by young adulthood: a prospective cohort analysis from the Great Smoky Mountains Study. J Am Acad Child Adolesc Psychiatry. 2011; 50: 252-261 Summary Full Text Full Text PDF PubMed Scopus (198) Google Scholar Mental disorder in adolescence increases the risk of later adult disorder, 4 Clark C Rodgers B Caldwell T Power C Stansfeld S Childhood and adulthood psychological ill health as predictors of midlife affective and anxiety disorders. Arch Gen Psychiatry. 2007; 64: 668-678 Crossref PubMed Scopus (129) Google Scholar , 5 Fergusson DM Boden JM Horwood LJ Recurrence of major depression in adolescence and early adulthood, and later mental health, educational and economic outcomes. Br J Psychiatry. 2007; 191: 335-342 Crossref PubMed Scopus (201) Google Scholar , 6 Pine DS Cohen P Gurley D Brook J Ma J The risk for early-adulthood anxiety and depressive disorders in adolescents with anxiety and depressive disorders. Arch Gen Psychiatry. 1998; 55: 56-64 Crossref PubMed Scopus (1316) Google Scholar and adults with mental disorder often have their first episode in adolescence. 1 Costello EJ Copeland W Angold A Trends in psychopathology across the adolescent years: what changes when children become adolescents, and when adolescents become adults?. J Child Psychol Psychiatry. 2011; 52: 1015-1025 Crossref PubMed Scopus (484) Google Scholar , 7 Newman DL Moffitt TE Caspi A Magdol L Silva PA Stanton WR Psychiatric disorder in a birth cohort of young adults: prevalence, comorbidity, clinical significance, and new case incidence from ages 11 to 21. J Consult Clin Psychol. 1996; 64: 552-562 Crossref PubMed Scopus (492) Google Scholar Therefore, adolescence is potentially an important time for mental health interventions to reduce both present and long-term impairment. However, there is little detailed knowledge about the prognosis of common adolescent mental disorders during the transition to adulthood. A greater understanding of the course and prognosis of adolescent-onset common mental disorders is needed to identify those at highest risk of later problems, to inform decisions about when to intervene, and to help allocate clinical resources efficiently. The prognosis of common mental disorders in adolescents: a 14-year prospective cohort studyEpisodes of adolescent mental disorder often precede mental disorders in young adults. However, many such disorders, especially when brief in duration, are limited to the teenage years, with further symptom remission common in the late 20s. The resolution of many adolescent disorders gives reason for optimism that interventions that shorten the duration of episodes could prevent much morbidity later in life. Full-Text PDF