Five decades of research on psychological treatments of depression: A historical and meta-analytic overview.

Since the 1970s, hundreds of randomized trials have examined the effects of psychotherapies for depression, and this number is increasing every year. In this study, we report outcomes from a living systematic review of these studies. We use Poisson regression analyses to examine if the proportions of studies have changed over time across the characteristics of the participants, therapies, and studies. We also present a meta-analysis of the effects across the major types, formats, targets, and age groups. We included 562 randomized controlled trials (669 comparisons; 66,361 patients). Most trials are conducted in adults and the relative proportion of trials in children and adolescents, as well as in older patients is significantly decreasing. The effects in children and adolescents are also significantly smaller than in adults (p = .007). Cognitive behavior therapy (CBT) is by far the best examined type of therapy (52%), but not necessarily more effective than other therapies. Over time, the proportion of studies examining several other types of therapy is significantly decreased compared to CBT. The quality of trials has increased over time, but still, a majority do not meet basic quality criteria, not even in recent years. The effects found in studies with low risk of bias are significantly smaller than in other studies (b = -0.21; SE = 0.05; p < .001). Most trials are conducted in the United States, but the proportion of studies in other parts of the world is rapidly increasing. The evidence that psychotherapies are effective is strong and growing every year. (PsycInfo Database Record (c) 2023 APA, all rights reserved).