Dr. John Rush, senior investigator, said the results send a strong message regarding the importance of long-term treatment for the disorder. The current study is the first to look systematically at the long-term impact of treatment for depression on the lives of patients and at the impact of discontinuing treatment.

"Chronic depression is an enemy that attacks a person's entire life. The disease incapacitates its victim, laying siege to relationships, educational and vocational success, and even the personal experiencing of joy, pleasure or satisfaction," said Rush.

In all, 635 patients with chronic depression completed twelve weeks of short-term treatment. Those who improved on treatment with sertraline (209) underwent a four-month continuation trial. Ninety-five percent of those patients responded favorably and were randomized to either sertraline or a placebo for an 18-month maintenance trial. The patients on active treatment reported improvement rates of 58 percent to 84 percent on tests qualifying psychosocial dynamics such as functioning, attitudes, and quality of life. Only 6 percent of the treated patients relapsed into depression. In contrast, the relapse rate for the placebo group was 23 percent.

Patients in the study had either chronic major depression or double depression, a low-level depression disorder interrupted by occasional episodes of major depression. Rush said both forms of the disease are frequently associated with significant degrees of social and vocational role impairment and lower levels of academic and vocational achievement.

"Study results showed that most patients not only feel much better after short-term antidepressant therapy but are able to function better, which is surprising considering the seriousness of the illness," Rush said. "Most responders are much improved in just six to twelve weeks; however, they tended to lose these psychosocial gains after being off medication a while."

The study findings are important, Rush said, because they suggest that the social and vocational problems patients with chronic depression experience are treatable and are not just ingrained personality traits.

"The study clearly shows that long-term treatment of chronic forms of depression can result in sustained psychosocial benefits," Rush said. "However, discontinuing drug treatment results in frequent re-emergence of symptoms."