Teen Bipolar Disorder What is Teen Bipolar Disorder? According to the National Institute of Mental Health, Bipolar Disorder is when a person has unusual mood changes; feeling very happy and more active than usual (manic) or feeling very sad and much less active than normal (depression). These mood swings are typically dramatic and unpredictable. Bipolar Disorder is often referred to as a manic-depressive illness. Diagnosis of Bipolar Disorder is often…