Talk therapy may help individuals who suffer from depression but findings of a new study have found that published scientific studies have overstated the benefits of psychotherapy.
The new study, which was published in the journal PLOS ONE on Sept. 30, has shown that while psychological treatment for depression does work, medical literature has painted a more rosy picture of its benefits.
The researchers said that this is so partly because among the clinical studies that investigate the efficacy of treatments for depression, those with less positive results were more likely to make it to journals compared with those with less favorable outcomes.
"This doesn't mean that psychotherapy doesn't work. 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.
"It's like flipping a bunch of coins and only keeping the ones that come up heads."
In their research, Hollon and colleagues looked at 55 U.S. National Institutes of Health grants awarded to clinical trials that looked at the efficacy of psychotherapy treatment on depression between the years 1972 and 2008. They found of these, only 13, or nearly a quarter, had not published the results.
Hollon's team contacted the researchers who conducted these 13 studies to inquire about their results and then conducted meta-analyses of both the published and unpublished data.
They found that findings of the unpublished but perfectly valid studies weighed down those of the rest of the studies suggesting that while psychological treatment indeed works, publication bias has inflated its effectiveness.
When the researchers asked the researchers of the unpublished research why they decided not to publish, they often answered that they did not think that the findings of the research were interesting enough or that they were distracted by their other obligations. Two of these studies were put up for peer review. Unfortunately, they were eventually rejected.
"The efficacy of psychological interventions for depression has been overestimated in the published literature, just as it has been for pharmacotherapy," the researchers wrote in their study. "Both are efficacious but not to the extent that the published literature would suggest."
The findings mirror what researchers have previously observed with antidepressants and other drugs. Hollon and colleagues added that decision makers, guideline developers and clinicians should know that published literature inflates the effects of leading treatments for depression.
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