Bipolar disorder affects work productivity more than depression.

Bipolar disorder negatively impacts work productivity at twice the rate of major depression, according to a study funded by the National Institute of Mental Health and published in the September 2006 American Journal of Psychiatry.

U.S. workers with bipolar disorder averaged 65.5 lost workdays in a year, compared to 27.2 for major depression. Even though major depression is six times as prevalent, bipolar disorder costs U.S. workplaces nearly half as much--$14.1 billion annually.

Researchers attribute bipolar disorder's higher toll primarily to more severe depressive episodes rather than agitated manic periods. Ronald Kessler, Ph.D., and Philip Wang, M.D., of …