Bipolar disorder costs twice as much in lost productivity as major depressive disorder, a study has found. Each U.S. worker with bipolar disorder averaged 65.5 lost workdays in a year, compared to 27.2 for major depression. Even though major depression is more than six times as prevalent, bipolar disorder costs the U.S. workplace nearly half as much -- a disproportionately high $14.1 billion annually, mostly due to bipolar disorder's more severe depressive episodes.