The most recent edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), major depression diagnosis requires five of nine specific symptoms nearly every day (depressed mood, loss of interest or pleasure in most activities, significant appetite or weight changes, changes in sleep, changes in activity, fatigue or loss of energy, guilt/worthlessness, concentration difficulties, and suicidality) that combined cause significant functional impairment across social, occupational, or educational domains.

The most current nationally representative U.S. estimates for teenage depression come from two data sources: 1) the National Comorbidity Survey–Adolescent Supplement (NCS-A), conducted in 2001 to 2004 on a sample of adolescents 13 to 18 years of age, and 2) the 2011 National Survey on Drug Use and Health (NSDUH), an annual survey of children 12 to 17 years of age

http://www.psychiatryadvisor.com/mood-disorders/depression-preventive-services-depression-adolescents-children/article/437319/

Lifetime risk for severe teenage depression is 9%. New US Task Force recommends screening!