According to the DSM-IV, bipolar disorder is a severe, recurrent, life-long illness that affects up to about 7% of Americans. Lifetime prevalence rates for bipolar I and II disorder range from .9% to 2.1%; for cyclothymia, a milder form of bipolar disorder, prevalence ranges from 3% to 5%.[1] More recent prevalence estimates are even higher.[2]
The World Health Organization reports that bipolar disorder was the sixth leading cause of years lived with disability, worldwide, in 1990 and remains among the top 10 causes today.[3]