Bipolar disorder in adolescents and children has recently become the focus of increasing study. During adolescence, normal developmental mood shifts may complicate the diagnosis of mood disorders. The commonality of symptoms associated with a variety of childhood disorders (especially ADHD) confuses the diagnostic process. Confusion regarding comorbidity can also occur if cross-sectional rather than longitudinal analyses are conducted. Genetic imprinting is the differential gene expression depending on whether the illness is transmitted maternally or paternally. Psychosocial functioning in bipolar youth has been described premorbidly and postillness onset (4.6 years) in a cohort of BMD I teenagers. Many young people who are initially diagnosed as having unipolar depression or dysthymia later meet criteria for a bipolar disorder. Electro-convulsive therapy (ECT) in adults with bipolar illness is one of the most effective treatments in both the depressive and manic phases of bipolar illness.