A combination of cognitive therapy and anti-depressant medicine can effectively treat patients suffering from severe non-chronic depression, according to a Vanderbilt University study.

The researchers said that similar beneficial effect was not observed in those diagnosed with chronic or less severe depression.

In the United States, about one in five women and one in 10 men suffer from major depression their lifetime.

Previous studies showed that about two-thirds of the patients with major depressive disorder will recuperate on anti-depressant medications; about one-third of the patients will experience full remission, but half will then deteriorate before fully recovering. Cognitive therapy is as effective as medication alone, but its effects tend to be long lasting.

The new study found that combining the two has the potential to enhance recovery rates by 6 to 33 percent.

"Our results indicate that combining cognitive therapy with antidepressant medicine can make a much bigger difference than we had thought to about one-third of patients suffering from major depressive disorder," said Steven Hollon, the Gertrude Conaway Professor of Psychology and lead author of the study, said in a statement. "On the other hand, it does not appear to provide any additional benefit for the other two-thirds."

"Now, we have to reconsider our general rule of thumb that combining the two treatments keeps the benefits of both," said Hollon.

For the study, the researchers followed 452 adult outpatients with chronic or recurrent major depressive disorder. Unlike previous studies that observed participants for a certain period of time, the researchers tracked them until they improved (full normalization of symptoms) and recovered (six months without relapse), which in some cases took as long as three years.

The researchers said that in countries like the United Kingdom, the use of combined cognitive therapy and anti-depressant medication is a standard treatment for several cases. The English National Health Service is training therapists in cognitive therapy along with other empirically supported psychotherapies.

The finding is published in the journal JAMA Psychiatry.

Tags Cognitive, Therapy, Drugs, Depression, Vanderbilt