The Effectiveness of Talk Therapy Is Not Overstated
by Andrew J. Gerber MD, PhD and John Prusinski
A recent article in the New York Times reports on a study published in the journal PLOS One which, according to the newspaper, concludes that “Medical literature has overstated the benefits of talk therapy for depression, in part because studies with poor results have rarely made it into journals.”
This effect is known as “publication bias”, that is, the likelihood that journals will be more inclined to publish articles with significant or positive results than those with null or negative results. This potentially results in a skewing of the available data, since studies with differing conclusions aren’t published (for a variety of reasons, including researchers declining to submit findings for publication).
In the case of the PLOS One study, a research team tracked down all grants funded by the National Institutes of Health from 1972 to 2008, and attempted to survey the results of all published and unpublished studies.
Before accounting for the unpublished studies, approximately 30 percent of psychotherapy patients being treated for depression were seen to achieve improvement or lasting recovery; after including the unpublished research, that figure was reduced to closer to 20 percent.
This appears to be a significant drop in positive results; however, other researchers and clinicians have found some meaningful problems with the PLOS One study. According to the New York Times article itself, “‘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.” The study was also said to have methodological problems, and to draw conclusions that go beyond the data.
However, the PLOS One study does offer a few interesting points, some contradicting the headline and the general thrust of the New York Times article:
- Among the different types of treatment control conditions (treatment-as-usual, pill-placebo, and non-specific [psychological placebo]), psychotherapy was found to be clearly superior.
- When psychological treatment was compared to antidepressants, no significant difference in outcomes was found.
- Finally, combining psychotherapy with medications was found to be superior to anti-depressant medications alone.
Interestingly, shortly after the publication of the New York Times article, the largest-ever randomized controlled trial of the effectiveness of psychotherapy for depression was published in the World Psychiatry Journal by the Tavistock and Portman NHS Foundation Mental Health Trust. The Tavistock Adult Depression Study (TADS) provides significant evidence for the efficacy of long-term psychoanalytic psychotherapy for patients suffering from chronic depression. The study compared outcomes for patients receiving psychoanalytic psychotherapy to those receiving standard NHS treatments (antidepressants, short-term courses of counseling or cognitive behavioral therapy). Among the key results: 44% of the patients who were given 18 months of weekly psychoanalytic psychotherapy no longer had major depressive disorder when followed up two years after therapy had ended; for those receiving the standard NHS treatments, the figure was only 10%.
As the Tavistock study reports, evidence-gathering regarding the effectiveness of longer term, more intensive psychoanalytic treatments is still in its early stages. In fact, one recent study found that psychodynamic psychotherapy is less effective in short-term treatments than brief focused therapies. However, over the long term, the evidence points to psychodynamic psychotherapy as a clearly superior treatment.