Four Decades of Outcome Research on Psychotherapies for Adult Depression: An Overview of a Series of Meta-Analyses

In the past 4 decades about 500 randomized trials have examined the effects of psychological treatments of adult depression. In this article the results of a series of metaanalyses of these trials are summarised. Several types of psychotherapy have been examined, including cognitive behaviour ther-apy, behavioural activation therapy, interpersonal psychotherapy, problem-solving therapy, nondirective supportive therapy, and short-term psychodynamic psychotherapy. All therapies are effective and there are no significant differences between treatments. Psychotherapies are about equally effective as pharmacotherapy, and combined treatments are more effective than either of these alone. Therapies are also effective in specific target groups, such as older adults, college students, patients with general medical disorders, but may be somewhat less effective in chronic depression, and in patients with comorbid substance use disorders. Treatments are effective when delivered in individual, group, and guided selfhelp format. The effects of psychotherapies have been overestimated because of the low quality of many trials and due to publication bias. Future research should not be aimed at the development of new psychotherapies for depression, on specific treatment formats or on therapies in specific populations, because the evidence indicates that all types and formats with human involvement are effective in all specific target groups. Future research should instead focus on a further reduction of the disease burden of depression. Specifically, it should focus on the possibilities of preventing the onset of depressive disorders, treatments of chronic and treatment-resistant depression, relapse prevention, and scaling up treatments, for example by using more guided self-help interventions.