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In this chapter, we describe the characteristics and clinical features of unipolar depressive disorders in children and adolescents, etiologic risk factors for depression onset and recurrence, and assessment and differential diagnosis of depressive disorders. We review recommended psychosocial and pharmacological treatments, and in conclusion, suggest areas for future investigation.
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GENERAL CONSIDERATIONS
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Child and adolescent depressive disorders are common, often recurrent, and generally continue into adulthood. These disorders are often familial and are associated with additional morbidity and mortality from comorbid substance abuse and from suicide and suicidal behavior. Patients also suffer educational and later occupational underachievement as well as relationship difficulties. Therefore, early identification and treatment of these conditions are important public health issues.
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The estimated prevalence of major depressive disorder (MDD) is 2% in children and 4–8% in adolescents (Avenevoli et al, 2015; Costello et al, 2003). After puberty, the risk for depression increases two- to fourfold, with a 20% incidence by the age of 18 years. The gender ratio in childhood is 1:1, and after puberty, the female/male ratio is 2:1. This may be related to higher rates of anxiety in females, changes in estradiol and testosterone at puberty, or socio-cultural issues related to female adolescent development (Angold et al, 1998).
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It is important to differentiate childhood-onset from adolescent-onset depression. Depressive disorders in adolescence are much more likely to be recurrent into adulthood. In the context of significant family adversity, prepubertal depression is most often comorbid with behavioral problems (Harrington, 2000). A less common form of childhood prepubertal depression is associated with strong familial loading for depression, high rates of anxiety, high risk for bipolar outcome, and recurrent mood disorder into adolescence and adulthood.
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Early-onset depression is multifactorial, including, but not limited to, familial factors, early life events, neuroendocrine changes, and genetics (Wilkinson & Goodyer, 2011). Twin studies show the importance of genetic and environmental factors, particularly in interaction. Familial risk factors for recurrent depressive disorders in youth include early-onset parental mood disorder. Non-familial depression has as risk factors parental substance-abuse disorder, parental criminality, family discord, and low family cohesion. Abuse may also be related to an earlier onset of depressive symptoms, as well as many other comorbid conditions. The contribution of early adverse life events is much greater in the setting of familial genetic risk factors (Wilkinson & Goodyer, 2011).
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The strongest single factor for developing MDD is familial loading for the disorder. The majority of studies including twin, adoption, and high-risk studies have shown a familial pattern with interaction of environmental and genetic factors. Family studies show a two- to fourfold increased risk for depression in offspring of depressed parents. Twin studies show a heritability for depression of 40–65% (Thapar & Rice, 2006). Evidence from twin ...