What is bipolar disorder?

The word bipolar means 'two extremes.' For the many millions experiencing bipolar disorder around the world, life is split between two different realities: elation and depression. So what causes this disorder? And can it be treated? Helen M. Farrell describes the root causes and treatments for bipolar disorder. [Directed by Owen Gent, Hugh Cowling, narrated by Addison Anderson, music by Hugh Cowling].