SYNTHESIS · Unveiling the Heterogeneity of Treatment Effects in Psychotherapy for Depression: A Synthesis of Individual Patient Data

Depression affects hundreds of millions of people, causing profound global suffering and underscoring the urgent need for effective treatments, like various psychotherapy types. Despite decades of research demonstrating psychotherapy’s effectiveness, outcomes remain stagnant, with over 50% of patients not responding to treatment. This stagnation underscores the necessity for targeted approaches to maximize treatment benefits, particularly given the heterogeneity of treatment effects (HTE) driven by individual differences and study contexts. SYNTHESIS addresses these challenges by utilizing an ambitious computational framework, which integrates Individual Patient Data (component) Network Meta-Analyses (IPD[c]NMAs) with machine learning (ML) to pave the way to precision psychology. It reconceptualizes psychotherapy as a dynamic, context-sensitive, and patient-centered network of interventions, addressing a key unanswered question: i.e., what is the optimal treatment, and its components based on individual differences. Moving beyond traditional approaches focusing on group averages, SYNTHESIS will uncover the HTE, addressing the generalizability crisis in psychotherapy research while advancing knowledge of treatment response variability. Key innovations include comparing all head-to-head comparison of psychotherapies, deconstructing these therapies into components, mapping their interactions with patient characteristics, and using ML to identify complex patterns in treatment responses within a causal IPD(c)NMA framework. Outputs such as an unparalleled IPD data warehouse, predictive models, and open-access clinical decision tools will revolutionize clinical research and practice. By advancing methodological approaches to targeted interventions, SYNTHESIS sets a new standard for precision psychology. Its scalable framework extends beyond depression, providing a blueprint for precision approaches in other disorders and disciplines where personalization is essential.