The Great Psychotherapy Debate: Since April, 2015 I review parts of The Great Psychotherapy Debate (Wampold & Imel, 2015) in the PPRNet Blog. This is the second edition of a landmark and sometimes controversial book that surveys the evidence for what makes psychotherapy work. You can view parts of the book in Google Books.
A couple of decades ago Martin Seligman famously said: “Whenever you hear someone demanding a double-blind study of psychotherapy, hold on to your wallet.” In this chapter, Wampold and Imel continue their examination of the Medical Model versus the Contextual Model for psychotherapy by discussing the viability of double-blind placebo control designs in psychotherapy. This topic sounds a little esoteric, but it’s not – this issue reaches into the very core of the definition of psychotherapy. A placebo-controlled trial in medicine often involves comparing a medication that contains an active biochemical ingredient versus a “sugar pill” that is exactly like the medication but without the active biochemical ingredient. Key to the placebo controlled design is that the health care provider, the patient, nor the researcher/evaluator knows which patient received which pill (i.e., the classic “double-blind” design). However, double-blinding is impossible in psychotherapy – the therapist must know what they are providing, which means that they know which treatment is expected to be effective, and which treatment is favoured by the researchers. Further, the researchers know which patients are getting which intervention of study condition. This affects a critical aspect of psychotherapy, that is, the therapist’s ability to provide a good rationale for the disorder and for the efficacious actions of the therapy. Additionally, patients are often aware that they are getting a pseudo-treatment in the placebo, and so their expectation of outcomes is also lowered (actually, this is often true in medical trials as well as most medications have side effects, and the absence of a side effect signals to the patient and the researcher that the patient is receiving the placebo). Wampold and Imel argue that common factors like emotional arousal, an acceptable explanation of the disorder, an understanding and empathic therapist, a structure to the treatment, and therapist and client expectations and hope are integral to the effectiveness of psychological therapies. They further argue that these are the very factors that medical trials try to control with a double-blind placebo controlled trial. Nonetheless placebo-like controls have been tried in psychotherapy to test the active or specific ingredients of a therapy – that is, to isolate the effects of active ingredients from the relationship context of the therapy. Placebo-like controls in psychotherapy have been called: minimal treatment, supportive counselling, non-directive counselling, etc. However, as mentioned, these placebo control conditions often contain elements that are integral to the effectiveness of psychotherapy, like: emotional arousal, an empathic therapist, and client expectations. And so not surprisingly, after reviewing meta-analyses of placebo-like conditions in psychotherapy research, Wampold and Imel conclude that when the studies are well constructed, these placebo-like conditions perform nearly as well as evidence-based treatments.
What is the take home message for the clinician of this seemingly esoteric topic about research design? Although the placebo-controlled double-blind randomized design is the gold standard in medical research, this design is not possible or even logical for psychotherapy. The relationship, therapist factors, expectations, and contextual factors that one tries to control in a placebo-controlled trial are some of the very ingredients that are active in psychotherapy. The technical and specific ingredients of psychotherapies (e.g., transference interpretations, cognitive restructuring, two-chair techniques, etc.) are also part of the mix; but in the end, one cannot separate contextual relationship factors from techniques when it comes to providing psychotherapy.