Treatment-specific elements of psychosocial interventions delivered by non-specialist providers for the treatment of common mental disorders: a three-tiered taxonomy of active elements

Over the past decades research into psychotherapy has disproportionately focused on treatment outcomes while largely neglecting the underlying processes. Consequently, the understanding of how, for whom, and under what conditions psychotherapies are effective remains limited. To achieve this, it is essential to identify the efficacy of the individual, treatment-specific elements embedded in psychological and social interventions. This requires these elements to be identified, defined, and classified. We developed a taxonomy of treatment-specific elements of psychosocial interventions delivered by non-specialist providers for common mental disorders (depression, anxiety, related somatic complaints). We systematically reviewed 11 evidence-based intervention manuals and coded their treatment-specific elements. The resulting three-tiered taxonomy comprises 39 techniques, organized into nine components, and further grouped into five overarching families. Each element was assigned an intensity score to distinguish between core and peripheral elements. All manuals (100%) included “psychoeducation” and some form of “cognitive reframing”, particularly strategies that assist clients in linking thoughts, emotions, and behaviors. “Problem management” and “relaxation” were also widely represented, as were techniques to “strengthen social support” (73%). “Interpersonal focus” (64%) and “behavioral activation” (45%) were moderately present, while “acceptance and mindfulness” and “emotion regulation” appeared less frequently (27%). Taxonomies, particularly those based on transdiagnostic frameworks, help move beyond one-size-fits-all approaches in psychotherapy research and practice. Taxonomies are foundational to predicting how individuals with specific characteristics will respond to the active elements embedded within therapy protocols. The proposed taxonomy provides a basis for linking qualitative and quantitative research, which is instrumental to personalized care in poor-resource settings.