Major Depressive Disorder

Major depressive disorder in children and adolescents is a mood disorder defined by one or more discrete episodes of persistently low or irritable mood and loss of interest, accompanied by changes in sleep, appetite, energy, concentration, and self-worth that cause distress or impairment. In young people irritability may substitute for sadness, and the disorder is a major source of disability and a leading risk factor for suicide.

Definition

Major depressive disorder is characterised by one or more major depressive episodes, each comprising at least two weeks of depressed or irritable mood and/or markedly diminished interest, together with a defined set of cognitive, somatic, and neurovegetative symptoms producing distress or functional impairment, in the absence of a manic or hypomanic episode.

Scope

The entry covers the definition and core features of major depressive disorder as it presents in youth, its developmental epidemiology, course and recurrence, established etiologic factors, and the structure of the evidence base. It is a reference description of the disorder and the research about it, not clinical guidance.

Core questions

• How does the presentation of major depression in children and adolescents differ from that in adults?
• What is the typical course of pediatric major depression, and how often does it recur into adulthood?
• How is the evidence on treatment of adolescent depression structured, and what does it show about benefits and risks?

Key concepts

• Major depressive episode
• Irritable mood as a youth presentation
• Anhedonia
• Recurrence and chronicity
• Gene-environment interaction
• Comorbidity with anxiety disorders
• Suicidality as a feature and outcome

Mechanisms

Major depression in youth is understood as a multifactorial condition arising from heritable vulnerability interacting with adversity such as maltreatment, loss, and chronic stress, against a background of pubertal and neurodevelopmental change. Thapar and colleagues emphasise that adolescent depression is shaped by hormonal, cognitive, and social transitions, which help explain its post-pubertal rise and emerging female predominance. Disturbances of stress-response and reward systems are implicated, and depression frequently co-occurs with anxiety, which often precedes it developmentally.

Clinical relevance

Major depression is a common, recurrent, and impairing condition of adolescence that is closely tied to academic, social, and suicide outcomes; reading the evidence on its course and treatment critically is central to the youth mental-health literature. This entry describes the disorder and the structure of its evidence base for reference purposes and is not a basis for diagnosing or treating any individual.

Epidemiology

Major depression is uncommon before puberty and rises markedly across adolescence, with prevalence increasing and a female predominance emerging by mid-adolescence. The meta-analysis by Polanczyk and colleagues estimated a worldwide pooled prevalence of any depressive disorder in children and adolescents near 2.6 percent, and depression in this age group carries a high risk of recurrence into adult life.

Evidence & guidelines

The AACAP practice parameter by Birmaher, Brent, and colleagues synthesises the assessment and management evidence for depressive disorders in youth, and the multicentre Treatment for Adolescents With Depression Study (TADS) is a landmark randomised trial comparing fluoxetine, cognitive-behavioral therapy, their combination, and placebo. Together these illustrate how the evidence base on adolescent depression is organised around controlled trials and guideline synthesis. They are cited here to describe the evidence landscape, not to recommend any specific treatment.

History

Major depression in childhood was long contested and only firmly accepted in the late twentieth century, after research established that children and adolescents could meet the same core episode criteria as adults, with developmentally specific features such as irritability. Subsequent randomised trials, including TADS in 2004, and guideline syntheses such as the AACAP practice parameter shaped the modern understanding of its course and treatment.

Debates

How should the benefits and suicidality risks of antidepressants in youth be weighed?

Trials such as TADS showed benefit for combined and pharmacologic treatment while also drawing attention to treatment-emergent suicidal ideation, and the balance of benefit and risk in pediatric antidepressant use remains a debated and closely regulated question.

Key figures

• Anita Thapar
• Boris Birmaher
• David Brent
• John March

Seminal works

• thapar-2012
• tads-2004
• birmaher-2007

Frequently asked questions

Can children and adolescents really have major depression?

Yes; major depressive disorder occurs in young people and is defined by the same core episode features as in adults, although irritable mood is a common presentation in this age group and prevalence rises after puberty.

Is depression in adolescence likely to recur?

Adolescent major depression carries a substantial risk of recurrence and of continued mood problems into adulthood, which is why its course is studied longitudinally.