We searched PubMed (Medline and life science journals) for articles in English using the search terms “adolescent depression” and “depression” (restricted to children), combined with additional search terms, specifically “epidemiology”, “gender”, “puberty”, “diagnosis”, “comorbidity”, “aetiology”, “life events”, “psychosocial”, “family”, “trends”, “genetics”, “gene-environment interaction”, “temperament”, “resilience”, “dysthymic disorder”, “treatment”, “medication”, “CBT”, “prevention”,
SeminarDepression in adolescence
Introduction
Unipolar depressive disorder is a common mental health problem in adolescents worldwide,1 with an estimated 1 year prevalence of 4–5% in mid to late adolescence.2, 3 Depression in adolescents is a major risk factor for suicide, the second-to-third leading cause of death in this age group,4 with more than half of adolescent suicide victims reported to have a depressive disorder at time of death.5 Depression also leads to serious social and educational impairments,6, 7 and an increased rate of smoking, substance misuse, and obesity.8, 9 Thus, to recognise and treat this disorder is important.
Depression is defined as a cluster of specific symptoms with associated impairment. The clinical and diagnostic features of the disorder are broadly similar in adolescents and adults (panel).10, 11 The two main classification systems (international classification of diseases-10 [ICD-10] and the American diagnostic and statistical manual of mental disorders-IV [DSM-IV]) define depression similarly, although DSM-IV makes one exception for children and adolescents, whereby irritable rather than depressed mood is allowed as a core diagnostic symptom.12 Nevertheless, depression in adolescents is more often missed than it is in adults,13 possibly because of the prominence of irritability, mood reactivity, and fluctuating symptoms in adolescents. Depression can also be missed if the primary presenting problems are unexplained physical symptoms, eating disorders, anxiety, refusal to attend school, decline in academic performance, substance misuse, or behavioural problems.
In some respects depression in adolescents can be viewed as an early-onset subform of the equivalent adult disorder because of its strong links with recurrence later in life.14 The illness has similar clinical features and patterns of neural activity to that in adults, and its occurrence is also associated with a family history of the disorder.11 However, important differences exist between the two disorders, particularly in treatment response, with strongly divided opinions about best treatment practices.10 Depression in prepubertal children is less common than depression in adolescents or adults, and seems to differ from these disorders with respect to some causative, epidemiological, and prognostic features.15, 16
We focus on unipolar depression in adolescents. When evidence is available, we focus on depressive disorder rather than its symptoms. However, in some instances, the only available data are based on studies in which depressive symptoms are reported. Such cases are noted, although there are generally strong similarities in research findings for depressive symptoms and depressive disorder.
Section snippets
Epidemiology
The prevalence of depression in children is low (<1% in most studies)17 with no sex differences, and then rises substantially throughout adolescence.18 Many factors could explain the recorded post-pubertal rise in prevalence because adolescence is a developmental period characterised by pronounced biological and social changes.19, 20 The most commonly postulated contributors are puberty and brain and cognitive maturation. They include enhanced social understanding and self-awareness,21 changes
Cause and pathogenenesis
Because of the clinically heterogeneous and diverse causes of the illness, to understand the pathogenesis of depression in adolescents is challenging. Like many other common health disorders, several risk factors interact to increase the risk of depression in a probabilistic way. To assess the contribution of any single risk factor in isolation and to identify crucial developmental periods when exposure is especially risky is difficult because many individual, family, and social risks are
Resilience
Many children who are at high-risk for depression through familial predisposition and exposure to adversity do not develop the disorder.101 Research into depression resilience has the potential to identify targets for prevention of depression. Individual factors that have been reported to protect against the development of depression in high-risk adolescents include inherited factors and high intelligence, as well as potentially modifiable factors such as emotion-regulation capacities, coping
Detection and diagnosis
A diagnostic approach is needed when decisions about treatment of adolescents with depression have to be made. This approach allows clinicians to apply evidence from treatment trials, make decisions on the risk-benefit ratio for medication, and rationalise referral to expensive specialist resources (if available). Depression can also be thought of as lying along a continuum.106 Subsyndromal depression in which adolescents have high levels of symptoms that do not meet the diagnostic threshold
Treatment
Treatment data in adolescents have been reviewed (figure 2).10, 129 Three important issues are highlighted. First, treatment choices are not the same in adolescents as in adults. Second, best treatment practice is controversial because accepted practice and clinical guidelines vary in different countries, and because of concerns about the use of antidepressant drugs in patients younger than 18 years, with some recommendations based on consensus rather than on evidence. Third, the evidence
Prevention
In view of the disability associated with depression in adolescents, prevention or at least delay of onset of the disorder is important.101, 129 Prevention strategies could be aimed at reduction of modifiable risks and promotion of factors to protect high-risk children from the effects of adversity and interrupting risk pathways. Prevention methods have been much discussed in an Institute of Medicine report and a meta-analysis.101, 147 Both concluded that a targeted and indicated prevention
Conclusion
Despite the global importance of depression in adolescence, many knowledge gaps exist. Further development of pragmatic, cost-effective methods of detecting, assessing, and treating adolescent depression in non-specialist contexts and low-income and middle-income countries is an important priority in view of the scarcity of resources. The knowledge gap with regard to relapse prevention is also noticeable. Finally, prevention strategies seem important because of the complexities and costs
Search strategy and selection criteria
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