Bipolar I disorder (pronounced "bipolar one" and also known as manic-depressive disorder or manic depression) is a form of mental illness. A person affected by bipolar I disorder has had at least one manic episode in his or her life. A manic episode is a period of abnormally elevated mood and high energy, accompanied by abnormal behavior that disrupts life.
Most people with bipolar I disorder also suffer from episodes of depression. Often, there is a pattern of cycling between mania and depression...
Tricyclic antidepressants work by increasing levels of the mood chemicals serotonin and norepinephrine in the brain. However, because they may sometimes increase the risk of mania or rapid cycling -- as well as heart problems if you take heart medication -- these drugs are less often recommended for bipolar disorder.
SOURCES: WebMD Medical Reference with The Cleveland Clinic: "Bipolar Disorder (Manic Depressive Disorder)." WebMD Assess Plus: Bipolar Disorder Assessment. National Institute for Mental Health: "Step-BD Womens Studies." Massachusetts General Hospital Bipolar Clinic & Research Program. MedicineNet.com: "Bipolar Disorder (Mania)." WebMD Medical Reference with The Cleveland Clinic: "Effects of Untreated Depression." American Psychiatric Association: "Practice Guideline for the Treatment of Patients With Bipolar Disorder."