When provided by experienced psychotherapists, cognitive therapy may be as effective as antidepressant drugs in initial treatment of moderate to severe depression, a new study suggests.

The study, published in the April issue of the journal Archives of General Psychiatry, included 240 people with moderate to severe depression. One group of 60 people received cognitive therapy, another group of 120 received antidepressant medication (usually Paxil), and a third group of 60 received a placebo pill.

According to University of Pennsylvania researchers, patients in the cognitive therapy group attended two 50-minute sessions a week for the first four weeks of the study. They went to one or two sessions a week for the middle eight weeks and to one session a week for the final four weeks of the study.

After eight weeks of treatment, response rates were 50 percent in the medication group, 43 percent in the cognitive therapy group and 25 percent in the placebo group. After 16 weeks of treatment, response rates were 58 percent for patients receiving either medication or cognitive therapy. Remission rates were 46 percent for patients receiving medication and 40 percent for those in the cognitive therapy groups.

“On the whole, these findings do not support the current American Psychiatric Association guideline, based on the TDCRP (the Treatment of Depression Collaborative Research Program) that ‘most (moderately and severely depressed) patients will require medication,’ ” the study authors wrote.

“It appears that cognitive therapy can be as effective as medications, even among more severely depressed outpatients, at least when provided by experienced cognitive therapists,” they wrote.