Symptom-specific improvement across therapies and their putative mediators: a mediation network intervention analysis

This is an original manuscript of an article published by Taylor & Francis in Psychotherapy Researchon March 2024, available online (Open Access): https://doi.org/10.1080/10503307.2024.2320349.The original manuscript was revised and rewritten, please refer to the published article. Objective: To examine differential symptom-specific improvements across the therapies Cognitive Behavioral Analysis System of Psychotherapy (CBASP) and Supportive Psychotherapy (SP) in patients with persistent depressive disorder (PDD), incorporating interpersonal problems, and social functioning as potential mediators. Method: We conducted a three step Bayesian mediation network intervention analysis with data from a randomized controlled trial. Here, chronically depressed patients received either treatment with CBASP or SP. Three change score networks were calculated to investigate (1) differential symptom-specific improvements, (2) differential treatment effects on potential mediators, and (3) associations between change in symptoms and change in potential mediators. Results: There was no strong evidence for differential symptom-specific improvements across therapies. However, sleeping problems, self-esteem, and social functioning showed very small evidence for greater improvement with CBASP. Improvement in social functioning was associated with greater improvement in self-esteem and greater decrease in hopelessness with CBASP. “Interpersonal problems” and “impaired social functioning” were strongly related to each other and to depressive symptoms, which also were clearly associated with each other. Conclusion: The results suggest that changes in social functioning might mediate the associations between treatment with CBASP and specific symptoms. Future research needs to investigate potential mediators by testing postulated working mechanisms of therapies.