1. Adolescents (13-17) diagnosed with a major depressive episode (MDE) (DSM-IV criteria) from either major depressive disorder (MDD) or bipolar disorder (BPD). BPD can present as a major depressive episode, with previous or subsequent cycling into a hypomanic, manic, or mixed episode. By definition, major depressive disorder MDD requires the presence of a major depressive episode, without cycling into a hypomanic, manic, or mixed episode.