Special Populations: Treatment-Resistant Depression in Children and Adolescents.

Major depressive disorder is a substantial public health challenge impacting at least 3 million adolescents annually in the United States. Depressive symptoms do not improve in approximately 30% of adolescents who receive evidence-based treatments. Treatment-resistant depression in adolescents is broadly defined as a depressive disorder that does not respond to a 2-month course of an antidepressant medication at a dose equivalent of 40 mg of fluoxetine daily or 8 to 16 sessions of a cognitive behavioral or interpersonal therapy. This article reviews historical work, recent literature on classification, current evidence-based approaches, and emerging interventional research.