Reward-Related Processes and Brain Function

This study will examine and compare brain changes during decision-making in healthy adolescents and adolescents who are anxious or depressed. The findings may provide a better understanding of mechanisms that lead to depression or anxiety. Adolescents between 9 and 17 years of age and adults between 20 and 40 years of age in the following categories will be enrolled in this study: * Healthy adults * Healthy adolescents * Adolescents with major depression * Adolescents with anxiety disorder (generalized anxiety disorder, social phobia, or/and separation anxiety disorder) The study involves three visits, as follows: Visit 1 Visit 1 consists of three parts for both child and adult participants: * Part 1: Staff will meet with participants for a standard psychiatric interview, which will include questions about the participants feelings, experiences and behavior both past and present. For adolescent participants, staff will meet with the child alone, the parent alone, and the child and parent together. * Part 2: Participants will perform a series of simple tasks involving shapes, letters, and numbers. They will have a medical history, physical examination and blood draw. In addition, adolescents will have a urine drug test. * Part 3: Adults and those adolescents who will undergo magnetic resonance imaging (MRI) in Visit 3 will receive training to familiarize them with the procedure. Visit 2 * Adolescents will again be asked standardized questions regarding their feelings, experiences and behavior, and will then perform a series of simple decision-making tasks on a computer. * Adults will undergo MRI scanning, as described below in Visit 3 for adolescents. This concludes the participation of adults in the study. Visit 3 Adolescents will have one of the following two procedures: \- Decision-making task using a computer. Small electrodes will be placed on the child s wrists, face and fingers to monitor muscle tone and skin humidity during the task. Or * MRI, a