Johnsen, T. J., & Friborg, O. (2015, May 11). The effects of cognitive behavioral therapy as an anti-depressive treatment is falling: A meta-analysis. Psychological Bulletin. Advance online publication. http://dx.doi.org/10.1037/bul0000015
Depression is a highly debilitating disorder and ranked third in terms of disease burden in the world. Cognitive behavioral therapy (CBT) is an effective treatment for depression that was introduced over 40 years ago. In part, CBT sees depression as caused by maladaptive thoughts that maintain emotional distress and dysfunctional behavior. Reducing depression is achieved by eliminating the impact of or chancing maladaptive thoughts. CBT is the most researched psychological treatment for depression, and the research goes back several decades. A number of technical variations and new additions have been made over the years to CBT to improve patient outcomes. The volume of research and its history provides a unique opportunity to assess time trends in the effects of CBT. In this meta analysis, Johnsen and Friborg asked: “have the effects of CBT changed over time”? They also looked at whether client factors (e.g., demographics, symptom severity), therapist factors (e.g., age, experience, training), common factors (e.g., therapeutic alliance, client expectancies), and technique factors (e.g., fidelity to a treatment manual) can explain these trends. Johnsen and Friborg reported on 70 studies of 2,426 patients conducted from 1977 to 2014. Males accounted for 30.9% of patients, 43% had comorbid psychiatric conditions, and the average patient was at least moderately depressed. The average effect of CBT in reducing depression was large (g = 1.46 after accounting for publication bias). Women had better outcomes, studies with poorer methodological quality showed larger effects, and patients of more experienced therapists had better outcomes. There were too few studies measuring therapeutic alliance to assess the effect of common factors on outcomes. Most interesting was a significant relationship between effect sizes and year of publication. That is, the effects of CBT declined significantly over the years, though the average effect remained large. Surprisingly, there was a steeper decline for studies that used a treatment manual compared to those that did not. No other variables were reliably associated with this decline.
Women and patients of more experienced therapists appear to benefit most from CBT. Although the effects of CBT declined over time, the treatment remained highly effective. Johnsen and Friborg’s study could not easily explain this decline. The authors suggested that the placebo effect (expectation on the part of patients, researchers, and therapists) is typically stronger for new treatments. However, as time passes the strong initial expectations tend to wane thus reducing the overall effect of the intervention. They also suggested that CBT treatment outcomes may be improved not by technical variations and new additions, but by better ways of integrating common, therapist, and client factors.
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