Serious mental illnesses became not only a national problem, but costs the United States an estimated $193 billion yearly in lost earnings, according to a recent study examining the consequences of mental disorders.

The study, funded by the National Institutes of Health's National Institute of Mental Health, found that lost earning potential in workers with serious mental illnesses (SMI) accounts for a large part of the financial burden the illnesses create.

The study, published in the American Journal of Psychiatry, surveyed data from nearly 5,000 participants between the ages of 18-64 in 2002. Researchers determined that people suffering from a SMI —which is any condition linked to suicidal behaviors or frequent violent acts, that significantly impaired a person's ability to function for at least 30 days over the past year — earned at least 40 percent less than people in good mental health.

This is more than obvious expenses such as medications, hospitalizations and clinic visits.

Lost earning potential, costs associated with treating coexisting conditions, Social Security payments, homelessness and incarceration are just some of the indirect costs associated with mental illnesses that have been difficult to quantify, Dr. Thomas R. Insel, director of the National Institute of Mental Health, said in a statement.

This study shows us that just one source of these indirect costs is staggeringly high.

Of the 86 percent of survey respondents who reported earning income, those with serious mental illness averaged $22,545 in yearly wages, compared with healthy workers' average income of $38,852. The study also showed that men with SMI's took a more significant financial hit than women.

The results of this study confirm the belief that mental disorders contribute to enormous losses of human productivity, lead researcher Ronald C. Kessler, of Harvard University, said in a statement.

Yet this estimate is probably conservative, because the [survey used] did not assess people in hospitals or prisons, and included very few participants with autism, schizophrenia or other chronic illnesses that are known to greatly affect a person's ability to work. The actual costs are probably higher that what we have estimated.