Effectiveness Of Talk Therapy For Depression Inflated By Publication Bias

By Victoria Kim 10/09/15

Has the effectiveness of talk therapy been overstated by psychologists?

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The effectiveness of talk therapy for depression has been inflated in the scientific literature, leading psychiatrists and psychologists to be a little too optimistic about the practice, say researchers.

The study, published in the journal PLOS ONE, found that publication bias in the research world—which occurs when studies finding that a treatment works are more likely to be published than those with a negative result—is the reason why certain talk therapy clinical trials have never been published.

A similar study from 2008 found that publication bias had the same effect on antidepressant drugs. For years, the study was used to suggest that people with depression should choose talk therapy over drug treatment.

But Erick Turner, a psychiatrist and researcher at Oregon Health and Science University, and an author of both the 2008 study and the new study on talk therapy, was not convinced that this was the answer. He wondered, “Why should we be recommending this other treatment when it might be just as fraught with publication bias as the drug literature is?”

So Turner and his colleagues set out to find whether psychotherapy research had the same bias as drug research. As their findings show, Turner’s skepticism was justified. After a review of 55 National Institutes of Health grants awarded between 1972 and 2008, which paid for clinical trials of psychotherapy for depression, the researchers found that nearly a quarter of these trials were never published.

“And when you bring in the unpublished data it brings down the apparent efficacy of psychotherapy for depression” by about 25%, said Turner.

The findings even the playing field and should quell any unjustified criticisms of drug treatment for depression, said Steven Hollon, a professor of psychology at Vanderbilt University and an author of the study.

Both talk therapy and antidepressants work, but are “just not as efficacious as we think they are,” said Hollon.

Publication bias is a widespread problem throughout the research world. Researchers are rewarded for making a splash rather than being honest, said Kay Dickersin, a professor of epidemiology at Johns Hopkins Bloomberg School of Public Health.

“I think the question that’s really arisen is, how much of what’s out there should we really believe,” Dickersin said.

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