by Michael D. Anestis, Ph.D.
Well now...it's been a while. I started my job as an assitant professor in the Department of Psychology at the University of Southern Mississippi around a year ago and just a week or so ago got around to asking the legal department for the go ahead to actively post on this site while self-identifying as a faculty member. That being said, approval was granted and here we are live with new content. My vision for this site going forward is sporadic posts by Joye, myself, and friends/colleagues of ours with a large chunk of content coming from graduate students. When Joye and I were grad students we gained a TON from forcing ourselves to stay current on literature and to disseminate our knowledge. My hope is to provide a similarly valuable experience for current grad students and, in doing so, help them learn to translate their scientific accomplishments into language that consumers can identify with and use to make informed choices about their mental health care.
My plan with this first post is to pick up where we left off by discussing a topic that frequently made its way to the forefront in PBB discussions: the evidence base for psychodynamic psychotherapy in the treatment of various mental illnesses. I chose this topic because I've come across a couple of news articles centering on one or both of the studies I'll cover today and, in these articles, the notion that the results support equivalence between psychodynamic therapy (PT) and cognitive behavioral therapy (CBT) was advanced. Such claims always make me curious to what extent the coverage of the data (and discussion of the data by the authors themselves) actually matches the results of the study.
Both of the studies I'll be reviewing came from the research team of Falk Leichsenring, whose work we have covered previously a number of times. At one point, we discussed controversial work he published claiming that long-term psychotherapy is superior to shorter term approaches (link; link). Another time, Joye wrote a piece summarizing a randomized controlled trial (RCT) that he and his colleagues conducted in which PT was compared to CBT in the treatment of generalized anxiety disorder (GAD; link). The first study we'll cover today features 12-month follow-up from that GAD study.
Study 1 - PT vs CBT in the treatment of GAD - 12-month follow-up
If you click on the link above, you'll see from Joye's original article that, in their prior publication on this topic, Leichsenring and colleagues reported that, at the end of treatment, CBT had outperformed PT in terms of worry, trait anxiety, and depression (the core features of GAD). At 6-month follow-up, the between group difference on depression became non-significant, but CBT continued to outpeform PT in the terms of worry and trait anxiety. In numerous forums, these results were touted as equivalence between the two treatments. To me, however, this couldn't be further from reality. No matter how small the effect, a significant and persistent between group difference on the primary symptoms of the disorder that brought somebody into treatment is meaningful.
Now to the newer results. Simone Salzer, Christel Winkelbach, Frank Leweke, Eric Leibing, and Falk Leichsenring (2013) published 12-month follow-up data from this same sample (PubMed description). The results mirrored those from the 6-month follow-up, with CBT outperforming PT on worry and trait anxiety, the core symptoms of GAD. What this tells us is that PT is far from useless and certainly not harmful with respect to the treatment of GAD. It also tells us that it is a suboptimal choice for an individual suffering from GAD barring circumstances in which they do not respond to CBT (which will happen for many individuals, as is the case with any treatment for any condition).
Before moving onto study 2, I want to make a quick point. In prior conversations on topics similar to this, folks have pointed out that the focus on symptoms is problematic and that PT is better suited to treat the individual as a whole. I have two responses to this line of thinking and it seems important to mention them now rather than waiting to see if the topics re-emerge as folks read this. First, symptoms are remarkably important (and in the cases of symptoms like suicidal ideation and behavior, they're actually life-threatening). Individuals whose lives are crippled by panic attacks, the inability to be in front of others without fear of harsh evaluation, depressed mood, hopelessness, affective lability, non-suicidal self-injury, and other symptoms of mental illness will no doubt express great relief if a treatment is able to help them escape these problems. Second - and this is at least equally important - there is no evidence that PT actually does outperform CBT or any other evidence-based treatment for specific mental illnesses in the treatment of other more wholistic variables (e.g., quality of life). If there was, that would make for an interesting conversation; however, thus far, that evidence simply is not there.
Study 2 - PT vs. CBT in the treatment of social anxiety disorder
In the second study I want to review today, Leichsenring and colleagues reported results from a large RCT comparing PT, CBT, and a waitlist control condition in the treatment of social anxiety disorder (SAD; PubMed Description). Before discussing the results, I want to highlight a number of things that the authors did extremely well.
- Participants were randomized to treatment condition, which ensures that individuals in each condition do not systematically differ from one another and skew results spuriously to favor one treatment versus another
- The study was well-powered, with 209 individuals randomized to receive CBT, 207 randomized to receive PT, and 79 randomized to the waitlist control condition
- Treatment time was equal across conditions, ensuring that one treatment didn't outperform the other simply because individuals in that condition received more treatment
- Both treatments were manualized and treatment integrity was checked regularly and thoroughly, ensuring that therapists in each condition were acutally providing the treatment they were supposed to and doing so well
- Therapists in each condition were trained extensively in the use of the specific manual utlized in the study, ensuring that the therapists were qualified to provide the treatment at a high level.
- Assessments were conducted by individuals blind to the treatment condition of the participants, meaning that ratings of severity and improvement were not influenced by the expectations of the individual conducting the assessment.
- The authors used intent-to-treat (ITT) analyses, which include the data from individuals who drop out of treatment early. This ensures that one treatment does not gain an unfair advantage over another because individuals who drop out due to treatment failure aren't included in the data. On a side note, attrition was fairly equal across the three conditions, with 24% of individuals in CBT, 28% of individuals in PT, and 27% of individuals on the waitlist dropping out prior to the end of treatment.
The authors had six main outcome measures. The first two were measures of diagnostic status. Remission, defined as a score on the The Liebowitz Social Anxiety Scale (LSAS) of less than or equal to 30, measures what proportion of the individuals in each condition was below clinical levels on SAD symptoms by the end of treatment. Response, defined as at least a 31% reduction in LSAS score, served as a measure of what proportion of the individuals in each condition exhibited a strong response to treatment. The last four were self-report measures of key SAD and SAD-related symptoms: the LSAS, the Social Phobia and Anxiety Inventory (SPAI), the Beck Depression Inventory (BDI), and the Inventory of Interpersonal Problems (IIP).
So...what did they find?
Significance tests revealed that both treatments were superior to waitlist on remission and response. They further indicated that CBT outperformed PT on remission and that the two treatments were equal on response.
With respect to the self-report questionnaires, CBT outperformed PT on the LSAS, SPAI, and IIP and the two treatments were equal on the BDI. In other words, in measures of social anxiety and interpersonal problems - the core features of SAD - CBT produced better results. PT did not produce better results than CBT on any outcome.
The authors noted that the effect sizes for all between group differences were small and, indeed, this is an important fact to point out to readers. Statistical significance does not necessarily mean that the two treatments produced results that were so dramatically different that one treatment can and should be dismissed as an option. At the same time, consistent small effects favoring one treatment over the other on the specific symptoms that drove an individaul to seek treatment are not meaningless.
Speaking about these results, Dr. Leichsenring noted "As all differences between CBT and PDT are small, results do not justify (recommending) one of the treatments over the other." (link)
I find this quote difficult to comprehend. Yes, small differences aren't huge differences, but small differences on the symptoms causing the most impairment and/or distress in an individual's life are an important consideration and precisely the type of guidance we should use in determine the front line treatment for individuals seeking mental health care. If we were debating treatments for cancer or another physical ailment and were told that one produced consistently favorable results that were small in magnitude on the central components of the disorder, I suspect few would argue that the results were meaningless. The situation is no different here.
Overall, I applaud any effort to study the effects of PT on specific mental illnesses and the authors did a lot of things tremendously well in these trials, but it is VITAL that when the media discusses results from studies (and the authors of those studies provide quotes in the articles) the words in the article match the data. Otherwise, we're left with a game of telephone in which individuals who are motivated to provide one impression or another lead consumers further and further away from the actual evidence.