Workers took over a billion mental health days last year. According to a new study published in the October 2007 issue of the Archives of General Psychiatry, American workers took over a billion days off for mental health reasons. The new study defines work very broadly — a missed work day is considered as any day in which a person is unable to carry out their usual responsibilities or activities. Called "role disability," the new approach is designed to more better take into account both the direct and indirect cost of illness to society.

Drs. Kathleen Merikangas from the National Institute of Mental Health (NIMH), Ronald Kessler from Harvard Medical School and colleagues found that more than half of U.S. adults have a mental or physical condition that affects their role functioning. More than 1.3 billion days of role performance are lost each year in the U.S. because of mental illness, with major depression being primarily responsible.

Their findings showed that more than half of U.S. adults have a significant mental or physical condition, leading to an estimated 3.7 billion days per year out of role. Nationwide, about 2.4 billion disability days resulted from chronic physical conditions and about 1.3 billion disability days resulted from mental conditions. Chronic back-neck pain was the condition associated with the largest number of days out of role, (1.2 billion), followed by major depression, (387 million).

The findings suggest that health care resources may need to be reallocated, with more money going to mental health and physical therapies. "Previous research has found that, on the whole, the least amount of health resources are spent on research and treatment of musculoskeletal disorders and depression, even though these are the most prevalent and disabling conditions," said Dr. Merikangas. "These results illuminate the discrepancy between how we allocate our health care resources, and which illnesses have the most impact."