Barkham, M. & Lambert, M.J. (2021). The efficacy and effectiveness of psychological therapies. In In Barkham, W. Lutz, and L.G. Castonguay (Eds.) Bergin and Garfield’s Handbook of Psychotherapy and Behavior Change (7th ed.). Wiley. Chapter 5.
In this part of the chapter, Barkham and Lambert review the debate about which psychotherapy is most effect for a particular disorder. This is a debate that has been ongoing since the middle of the last century. The current status of this debate centers around questions like how big are the differences between treatments, are these differences clinically meaningful, and if the specific interventions of a particular therapy are not the cause of change, then what are? It turns out that the early estimations of differences in therapies favoring CBT were over-blown. This was caused by combining effects across different studies that did not directly compare the treatments in question (the technical explanation is that comparing the effects of CBT vs a wait list control group in one study to the effects of psychodynamic therapy to a control group in another study introduces a whole host of confounds that make interpreting the differences in effects across studies unreliable). When subsequent researchers conducted meta-analyses of the effects of psychological therapies and only included studies in which bona-fide therapeutic approaches were directly compared to each other in the same study, then the differences between therapeutic approaches were small and clinically irrelevant (and even those small effects were be wiped out by controlling for the researchers’ allegiance [i.e., the effect caused by the researchers’ preference of one therapy over another]). Another way to consider the question is to assess the effects of the specific interventions of a therapy. That is, if CBT is effective because of its cognitive or behavioral components, then removing a component of CBT should reduce its effectiveness. These are often referred to dismantling studies. However, reviews of these types of studies indicate that removing components of treatment seem to have little or no impact on patient outcomes. That is, the effect of a therapy seems to have little to do with the specific intervention associated with the therapy (e.g., cognitive restructuring, exposure and response prevention). In fact, by far the largest predictors of patient outcomes are the factors common across most therapies: the therapeutic alliance, therapist empathy, goal consensus, therapist interpersonal skills, cultural adaptation of therapies, and others.
This research domain is far from perfect, and the debate over which therapy is better unfortunately will likely continue for some time. However, clinically and from a public health perspective, this is not a useful debate and hopefully with time it will fade. Much more useful questions likely center around how we can improve therapist skills in those factors that lead to better patient outcomes. That is, regardless of theoretical orientation, can we train therapists to verbally express emotions and empathy, improve their capacity to develop and maintain the therapeutic alliance, and adapt their interventions to the patient’s culture, characteristics, and preferences?