Because of increased awareness and diagnosis, more people than ever before have a basic understanding of bipolar disorder, the condition formally known as manic depression. Yet myths persist about this mental disorder that causes mood shifts from depression to mania and affects a person's energy and ability to function. WebMD asked five bipolar disorder experts to help unravel what's myth and what's fact….Bipolar Myth No. 1: Bipolar disorder is a rare condition. Not so, according to statistics and research. In a given year, bipolar disorder affects about 5.7 million American adults, or about 2.6% of the U.S. population 18 and older, according to the National Institute of Mental Health. Estimates for children and teens vary widely, partly because there is debate about the criteria for diagnosis, say Thomas E. Smith, MD, a research scientist at the New York State Psychiatric Institute and an associate professor of clinical psychiatry at Columbia University College of Physicians and Surgeons in New York….