Five decades of research on psychological treatments of depression: A historical and meta-analytic overview.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 37971844 · doi:10.1037/amp0001250
What was done
Authors conducted a living systematic review and meta-analysis of randomized controlled trials (RCTs) investigating psychotherapies for depression published from the 1970s onward. They used Poisson regression to assess changes over time in participant, study, and therapy characteristics, and meta-analyzed clinical effects across therapy types, formats, target populations, and age groups.
What was found
The analysis included 562 RCTs with 669 comparisons and 66,361 patients. Most trials evaluated adults, while the proportion of studies in children, adolescents, and older adults significantly decreased over time. Treatment effects in children and adolescents were significantly smaller than in adults (p = .007). Cognitive behavior therapy (CBT) constituted 52% of all trials, though it was not necessarily more effective than other modalities, while the share of trials studying other modalities decreased over time. Trial quality improved over the decades, but a majority of studies still failed to meet basic quality criteria; studies with low risk of bias yielded significantly smaller effect sizes (b = -0.21, SE = 0.05, p < .001). Trials were predominantly conducted in the United States, though international representation is increasing.
Why it matters
This 50-year overview confirms that psychological interventions for depression are effective overall but underscores that true effect sizes are likely smaller than historically reported due to pervasive methodological bias in older and recent trials alike.
Limits
The abstract notes that the majority of included trials fail basic quality standards even in recent years, introducing substantial risk of bias. The evidence base is heavily skewed toward CBT, adults, and US populations, with declining relative research attention to youth and older populations.
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