Transcript: Bipolar disorder, once known as manic depression, affects nearly 6 million American adults. But what exactly is bipolar disorder?  Bipolar disorder-which used to be called Manic Depressive psychosis-is a severe mood disorder that causes unusual shifts in a person's mood, energy, and ability to function.  Different from normal ups and downs, the dramatic swings of bipolar disorder shift from periods of frenetic activity, or "manic" moods, which may include excessive spending, promiscuity, and little sleep, to hopeless "depressive" moods characterized by excessive sleep, lack of interest in life, and lasting sadness. Fortunately, bipolar disorder is treatable and people with this illness can lead full, productive lives.  It is estimated some 6 million Americans currently suffer from bipolar disorder.  Many groundbreaking creative thinkers are thought to have suffered from bipolar disorder, including Beethoven, Virginia Woolf, and Sylvia Plath.  In more recent years Ben Stiller, Sting and Larry Flynt have all spoken openly about living with bipolar disorder. Bipolar disorder typically develops in late adolescence or early adulthood.  While the precise mechanism that causes bipolar disorder is not entirely understood, but it is likely that both genetics and a person's environment are factors. Although the disease certainly tends to run in families, concordance rates for bipolar disorder between identical twins is just 50%, showing conclusively that genetics are not the sole cause of bipolar disorder.  There are actually several different forms of bipolar disorder.  The most common form, which involves recurring episodes of mania and depression, is called bipolar I disorder.  Some people never develop severe mania, and instead experience milder episodes known as hypomania that alternate with depression; this form of the illness is called bipolar II disorder. Just as there is a chronic form of low-grade depression known as Dysthymia, there is a similar chronic, cyclical low-grade version of bipolar disorder called Cyclothymia, in which both hypomanic and depressive behavior occurs and continues over at least a 2-year period.  People that experience severe mood shifts from mania or hypomania to depression and back again more than four times a year are said to have rapid-cycling bipolar disorder. Rapid cycling tends to develop later in the course of illness and is more common among women than men.  Because it is sometimes difficult to tell the difference between normal mood swings and the symptoms of bipolar disorder, many people suffer for years before the illness is properly diagnosed and treated. Once diagnosed, it is a treatable illness, but bipolar disorder must be carefully managed throughout a person's life.  Bipolar disorder is a complex illness-if you think you might be suffering from it, please see a mental health professional.Want to learn more? Check out other videos and sources on this site for more information.