Combined treatment with drugs and therapy appears most effective in treating severe nonchronic depression, according to results from a major new clinical trial. The trial, which indicates that such treatment can lead to a 30 percent improvement than simply using antidepressant medication alone, was published online by the journal JAMA Psychiatry on August 20.

Approximately one in five women in North American and one in 10 men battle major depression within their lifetime.

The director of the study, Steven Hollon, the Gertrude Conaway Professor of Psychology at Vanderbilt University, said in a statement, “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.” He continued, “On the other hand, it does not appear to provide any additional benefit for the other two-thirds.”

Prior studies have noted an improvement in approximately two-thirds of all patients with major depressive disorder when taking antidepressant medications and around one-third of patients will benefit from complete remission. However, half of these patients experience a relapse before completely recovering. Cognitive therapy is considered as beneficial as medication alone, but the effects are generally longer lasting. When the two treatment methods are combined, recovery rates increase by six, to 33 percent.

According to the National Institute of Mental Health, in 2012 approximately 16 million adults ages 18 or over in the U.S. had a minimum of one major depressive episode each year, a number that represents 6.9 percent of all adults in the U.S.