Millions of Americans Suffer from Major Depression

Millions of Americans suffer from major depression each year, and most are not getting proper treatment for this debilitating disorder, according to a two-year nationwide study reported in the June 18 Journal of the American Medical Association.

The study, led by researchers from Harvard Medical School, found high rates of major depressive episodes (MDE) in all segments of the U.S. population. The researchers measured the severity and duration of depression in more than 9,000 Americans 18 years or older and looked at MDE's effect on daily activities and treatment received, if any.

"This is the first study to assess clinical severity of depression in a community sample," said survey leader Ronald Kessler, HMS professor of health care policy.

"Critics have suggested that depression was over-estimated in earlier studies because of many people with mild depression being included even though they really don't need treatment," Kessler said. "But we built in a state-of-the-art clinical severity assessment, and we found that the majority of people with MDE are severe cases and only a small minority are mild cases. The average person with MDE in the past year reported an average of 35 days when they were unable to work or carry out other normal activities because of their depression.

"These findings confirm that depression is an enormous societal problem, both in terms of the number of people involved and in terms of clinical severity," Kessler said.

Although most people reporting depression in the past 12 months received some kind of treatment -- an improvement over earlier findings -- only one in five received treatment that met minimum standards of treatment adequacy established by the Agency for Health Care Policy and Research.

The researchers found that this problem of inadequate treatment was due to a mix of inappropriate dosing of antidepressant medications on the part of physicians, patient discontinuation of treatment, and the use of unproven treatments outside the medical and mental health system.

"While recently increased treatment is encouraging, inadequate treatment is a serious concern," Kessler and his co-authors write. "Emphasis on screening and expansion of treatment needs to be accompanied by a parallel emphasis on treatment quality improvement."

The study found that women and people previously married were most at risk for major depression over a lifetime; in a 12-month period, MDE was more common among homemakers, people never married, and those who had not completed high school or who were living in poverty. Neither geographic region nor urban versus rural residence was closely related to MDE.

The researchers found MDE affects 13 to 14 million American adults--roughly 6.6 percent--in a given year. In a lifetime, 16.2 percent of Americans--about 33 to 35 million--suffer from MDE.

The JAMA article is the first publication from the National Comorbidity Survey Replication, a broad-based national study of mental disorders. Co-authors of the study are at the University of Michigan, the National Institute of Mental Health (NIMH), the University of Texas Southwestern Medical Center, and Brigham and Women's Hospital/Harvard Medical School.

The study was funded by NIMH, the National Institute of Drug Abuse, the Substance Abuse and Mental Health Services Administration, and the Robert Wood Johnson Foundation.

HARVARD MEDICAL SCHOOLHarvard Medical School has more than 5,000 full-time faculty working in eight academic departments based at the School's Boston quadrangle or in one of 47 academic departments at 17 Harvard teaching hospitals and research institutes. Those Harvard hospitals and research institutions include Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Cambridge Hospital, Center for Blood Research, Children's Hospital, Dana-Farber Cancer Institute, Harvard Pilgrim Health Care, Joslin Diabetes Center, Judge Baker Children's Center, Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital, Massachusetts Mental Health Center, McLean Hospital, Mount Auburn Hospital, Schepens Eye Research Institute, Spaulding Rehabilitation Hospital, VA Boston Healthcare System.