With the development of empirically supported treatments over the decades, have youth psychotherapies grown stronger? To investigate, we examined changes over time in treatment effects for four frequently treated youth mental-health problems: anxiety, depression, attention-deficit hyperactivity disorder (ADHD), and conduct disorders. We used PubMed and PsycINFO to search for randomized controlled trials (RCTs) that were published between January 1960 and May 2017 involving youths between the ages of 4 and 18 years. We also searched reviews and meta-analyses of youth psychotherapy research, followed reference trails in the reports we identified, and obtained additional studies identified by therapy researchers whom we contacted. We identified 453 RCTs (31,933 participants) spanning 53 years (1963-2016). Effect sizes for the problem-relevant outcome measures were synthesized via multilevel meta-analysis. We tracked temporal trends for each problem domain and then examined multiple study characteristics that might moderate those trends. Mean effect size increased nonsignificantly for anxiety, decreased nonsignificantly for ADHD, and decreased significantly for depression and conduct problems. Moderator analyses involving multiple study subgroups showed only a few exceptions to these surprising patterns. The findings suggest that new approaches to treatment design and intervention science may be needed, especially for depression and conduct problems. We suggest intensifying the search for mechanisms of change, making treatments more transdiagnostic and personalizable, embedding treatments within youth ecosystems, adapting treatments to the social and technological changes that alter youth dysfunction and treatment needs, and resisting old habits that can make treatments unduly skeuomorphic.
Keywords: adolescents; children; mental health; meta-analysis; psychotherapy; youth.