Depression affects about 9.5% of the U.S. adult population each year. It is estimated that approximately 17% of the U.S. population will suffer from a major depressive episode at some point in their life. Depression causes 40 billion dollars a year in missed work and medical costs which makes this illness the leading cause of disability in America. Recent research suggests that between 1987 and 1997, the rate of outpatient treatment for depression in the United States tripled and that health care costs are skyrocketing higher each year. Research has also shown that depressed patients are less fit and have an 80 to 90 percent less workload than their age appropriate counterparts. This can also contribute to other physical health problems, which in turn could combine and intensify the symptoms of MDD.