Effectiveness of psychotherapy: Synthesis of a "meta-analytic research domain" across world regions and 12 mental health problems

The scientific output generated in psychology has surged in recent decades, including the number of studies investigating psychological treatments. To keep track of all this evidence, we developed the "Metapsy" meta-analytic research domain: a comprehensive system of open databases and tailored software that allows for rapid evidence generation. We leverage this novel infrastructure to summarize the effect of psychological treatment across 12 mental health problems and trace back the global expansion of psychotherapy research over the past 50 years. Including 1,029 studies with 85,952 patients, our results indicate small to moderate average benefits in treating psychosis (g = 0.32), suicidal ideation (g = 0.34), borderline personality disorder (g = 0.46), and prolonged grief (g = 0.49). In contrast, psychological interventions have large average effects on depression (g = 0.73), problem gambling (g = 0.80), panic (g = 0.83), generalized anxiety (g = 0.86), social anxiety (g = 0.95), obsessive-compulsive (g = 1.18), posttraumatic stress disorder (g = 1.18), and phobias (g = 1.25). Most available evidence (83.4%-86.1%) comes from high-income and Western countries, but their dominance is declining. We found no indication that psychotherapy is less effective in low- and middle-income countries (g = 0.38-2.41) or non-Western cultures (g = 0.74-2.20). We discuss ways to further enhance psychotherapy's public health impact, as well as how the meta-analytic research domain concept may be extended to other types of psychological research in the future. (PsycInfo Database Record (c) 2025 APA, all rights reserved).