Millions of Americans suffer from major depression

A Harvard Medical School study found high rates of depression throughout the U.S. population. The researchers analyzed the depression of over 9,000 Americans and evaluated depression's effect on daily activities and treatment received, if any.

Critics have theorized that depression has been reported as more widespread than it really is, said survey leader Ronald Kessler, HMS professor of health care policy. "But we found that the majority of people with depression are severe cases, and only a small minority are mild cases."

The inadequate treatment received by 80 percent of those who were treated sprang from inappropriate dosing of antidepressants by physicians, patient discontinuation of treatment, and the use of unproven treatments. "Emphasis on screening and expansion of treatment needs to be accompanied by a parallel emphasis on treatment quality improvement," Kessler's team writes.

The study found that women and people previously married were most at risk for major depression over a lifetime; in a 12- month period, depression was more common among homemakers, people never married, and those who had not completed high school or who were living in poverty.

The researchers found depression affects roughly 6.6 percent of American adults in a given year, and 16.2 percent of American adults in a lifetime.