“Psychotherapy does work. It just doesn’t work as well as you would think from reading the scientific literature”, said study author Steven Hollon, from the Department of Psychology of the Vanderbilt University in Tennessee. “Both are efficacious but not to the extent that the published literature would suggest”. When the team analyzed the published and unpublished results of those trials, they found that the published results skewed toward those that found positive outcomes for psychotherapy.
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For their study, Hollon and colleagues set out to investigate whether psychotherapy – a treatment that is frequently offered to patients with mild to moderate MDD – may also have been subject to publication bias. “Depression is a tough disorder to treat, and it’s very hard also to judge treatments because the symptoms of the depression naturally wax and wane – it’s a moving target”, said the researchers. The team then contacted the researchers of these studies to get their results, before adding the unpublished results to studies that were published and conducting a series of meta-analyses.
Doctors have long known that journal articles exaggerate the benefits of antidepressant drugs by about the same amount, and partly for the same reason – a publication bias in favor of encouraging findings.
As an example, they point to one study that identified 74 placebo-controlled antidepressant studies that had been submitted to the US Food and Drug Administration (FDA).
The study of talk therapy involved a review of 55 National Institutes of Health grants awarded between 1972 and 2008. The grants were handed out for clinical trials of psychotherapy for depression.
The new finding could help reverse an unfortunate side effect of the 2008 analysis of depression drugs, Turner says.
“Antidepressant medication is recommended as a first-line treatment for major depressive disorder in most treatment guidelines and the majority of depressed patients are now so treated in primary care”.
“There was a wave of just simple antidepressant bashing that went on and has continued”, Turner says. And the results were used to suggest that people with depression should choose talk therapy over drugs.
“The number of trials they looked at was fairly small, and the different psychotherapy approaches were all pooled together”, said Stefan Hofmann, a professor of psychology at Boston University. Similar conclusion has been revealed by the new study for talk therapy too. But he says that’s less likely to be a problem for patients.
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Of course, publication bias isn’t limited to depression treatments.
