Neurobiology of Depression in Children and Adolescents Gil Zalsman, MD a,b,c, * , Maria A. Oquendo, MD a,b , Larry Greenhill, MD b,d , Pablo H. Goldberg, MD a,b,d , Masoud Kamali, MD a,b , Andre´s Martin, MD, MPH e , J. John Mann, MD a,b a Department of Psychiatry, Division of Neuroscience, Columbia University, New York, NY 10032, USA b New York State Psychiatric Institute, New York, NY 10032, USA c Child and Adolescent Department, Geha Mental Health Center, Tel Aviv University, Petach Tikva, 49100, Israel d Department of Psychiatry, Child and Adolescent Division, Columbia University, New York, NY 10032, USA e Yale Child Study Center, Yale University, New Haven, CT 06520-7900, USA Early-onset major depressive disorder (MDD) and dysthymic disorder are recurrent or chronic familial disorders that tend to continue into adult- hood. They are often accompanied by other psychiatric disorders, such as substance use disorder and attention deficit disorder, that lead to poorer psychosocial and academic outcomes and may be complicated by suicidal behavior [1]. There is the question of whether adult-onset major depression is the same illness as depression that starts in childhood or adolescence. Some of the neurobiologic systems, such as the serotonin and noradrenergic systems, which are implicated in mood disorders, evolve significantly during child- hood and adolescence and may play a different role in pediatric- and adult-onset mood disorders. We review studies of the neurobiology of depressive disorders in children and adolescents. Most studies of childhood and adolescent depression and suicide have followed up the observations and methods used in studies of mood disorders and suicide in adults. These studies include neuroendocrine * Corresponding author. Child and Adolescent Department, Geha Mental Health Center, Tel Aviv University, PO Box 102, Petach Tikva 49100, Israel. E-mail address: zalsman@post.tau.ac.il (G. Zalsman). 1056-4993/06/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.chc.2006.05.010 childpsych.theclinics.com Child Adolesc Psychiatric Clin N Am 15 (2006) 843–868