"We know they both work so you assume when you put them together it's going to work better," said lead author Steven D. Hollon of the psychology department of Vanderbilt University in Nashville, Tennessee.
He would have liked to see that additive effect for the entire cohort of depressed patients, but for about two thirds of patients, adding cognitive therapy didn't matter, Hollon told Reuters Health.
Hollon and his team studied 452 adults with major depressive disorder who were randomly assigned to receive antidepressants alone or antidepressants and cognitive therapy.
All patients were given antidepressants at maximum tolerated levels and researchers frequently assessed patients' depression symptoms, so those who were not fully responding to one medication would be given another class of drug in addition, or instead of the first.
Twelve psychologists, a psychiatrist and a nurse-practitioner met with patients in the combination treatment group for 50-minute sessions twice weekly for at least the first two weeks, and at least weekly or monthly during continued treatment.
Researchers considered four continuous weeks of minimal depression symptoms to be remission, and another 26 weeks without symptoms to be recovery.
Of the 350 people who completed the study without dropping out or being removed, those in the combined treatment group were more likely to reach recovery than those in the medication-only group, according to the results released online August 20th in JAMA Psychiatry.
Overall, 73% of the combined treatment group achieved recovery, versus 63% of the medication-only group.
There was evidence that therapy also hastened the process for some patients. About 64% of those getting cognitive therapy plus medication achieved remission by the 12-month mark, versus 60% of those on medication alone. People in the combined treatment group also reached remission in an average 33 weeks versus 38 weeks for the group on medication alone.
But when researchers looked at the patients by the severity and persistence of their symptoms at the start, combined treatment only made a difference for the third of the group with severe, but not chronic depression.
"For those who were less severely depressed, they didn't need the additional therapy," Hollon said. "If you were chronic, you didn't benefit from it."
People with chronic depression had consistent depression symptoms for at least two years before the study began.
For those with severe, nonchronic depression, recovery was 30% more likely with combined therapy, which is a big effect, Hollon said.
Cognitive therapy, which is one of the most studied psychotherapy options for treating depression, requires the therapist to have special training, he said.
"The idea is to teach people how to monitor their moods," Hollon said.
He compared cognitive therapy to teaching someone to drive on ice - the normal human response is to pull back and steer away but the best strategy is actually be more active, spend more time going out and doing activities you like, not to pull away from personal interactions or activities.
In the U.S., treatment with only medication is most common, whereas in England and Western Europe combined treatment is already the standard, Hollon said.
"This is not an isolated finding but it does suggest we have more work to do for people who have chronic depression," said psychiatrist Dr. Michael E. Thase, of the Perelman School of Medicine at the University of Pennsylvania in Philadelphia and the Philadelphia Veterans Affairs Medical Center.
Thase, who wrote a commentary accompanying the new study, told Reuters Health that one question the study does not answer is how psychotherapy-only treatment would compare to medication-only or combined treatment.
Cognitive therapy can be twice as expensive as medications, but in the long run the therapy is cost effective in that it decreases the chances of relapse, Hollon said.
"People in this country don't get treated, and when they do they stick with one that's not working," he said.
It's important for patients to keep from getting stuck with a medication or treatment that's not working well, he said.
JAMA Psychiatry 2014.
(c) Copyright Thomson Reuters 2014.