Cuijpers, P., Driessen, E., Hollon, S. D., van Oppen, P., Barth, J., & Andersson, G. (2012). The efficacy of non-directive supportive therapy for adult depression: a meta-analysis. Clinical psychology review, 32(4), 280-291.
The research evidence indicates that there is very little difference between different types of psychotherapy (CBT, IPT, PDT, EFT, and others) in patient outcomes, especially for depression. Nondirective supportive treatment (NDST) also shows positive outcomes for various disorders. NDST is often used as a “placebo” condition in psychotherapy trials to control for common or non-specific factors. Common factors refer to those aspects that are common to all therapies, but that are not specific to any one therapy (e.g., therapist interpersonal skills, therapeutic alliance, client expectations). NDST does not involve specific therapeutic interventions like cognitive restructuring, transference interpretations, two-chair techniques, etc. In this meta analysis, Cuijpers and colleagues assessed those randomized controlled trials for depression in which specific treatments (e.g., CBT, PDT, IPT, EFT) or no treatment control conditions were directly compared to NDST. By doing so, the authors were able to estimate how much of patient outcomes were attributable to: specific effects of treatments (the difference between a specific intervention and NDST), common effects of treatment (the difference between NDST and no treatment), and extra-therapeutic factors (the effects of no treatment). The meta analysis included 31 studies with over 2500 patients with depression. Twenty-one comparisons included CBT, and the rest included IPT, PDT, or EFT. NDST was significantly less effective than other specific therapies (e.g., CBT, IPT, PDT, or EFT) at post-treatments g = −0.20 (95% CI: −0.32 to −0.08), but the effect was quite small. The difference between NDST and CBT alone (the most researched treatment type) was not statistically significant. Interestingly, when the authors controlled for researcher allegiance (an indication of which treatment was preferred by the researcher), the superior effects of specific treatments over NDST disappeared. NDST was significantly more effective than no-treatment, and the effect was moderate, g=0.58 (95% CI: 0.45–0.72). Pre- to post-treatment change in symptoms in the control condition was statistically significant, g = 0.39 (95% CI: 0.03–0.74), indicating the positive effects of extra-therapeutic factors on depressive symptoms (e.g., events in the patient’s life not related to therapy). Overall, the authors were able to estimate that almost 50% of patient outcomes could be attributed to common factors (therapist interpersonal skills, therapeutic alliance, client expectations, etc.), about 17% was due to specific therapy techniques (cognitive restructuring, two chair techniques, IPT interventions), and about 33% was due to extra-therapeutic factors (e.g., the natural course of depressive symptoms or other events in the patient’s life).
Factors like therapist interpersonal skills and managing the therapeutic relationship appear to account for most (50%) of why patients with depression get better. The specific interventions based on therapy models like CBT account for relatively less of patient outcomes (17%). The natural course of the disorder and other events in patients’ lives account for about a third of patient improvement. Therapists can learn how to maximize the effects of common factor skills through deliberate practice and training to identify and repair alliance ruptures to help their patients get better.