Effectiveness and mechanisms of Intensive Short-Term Dynamic Psychotherapy for treatment-resistant depression: a reanalysis of a randomized controlled trial.

Introduction: Intensive Short-Term Dynamic Psychotherapy has shown promising effects for treatment-resistant depression, but it remains unclear whether its hypothesized mechanisms - reducing emotional repression, negative affect, and psychological distress - actually mediate treatment outcomes. Methods: We reanalyzed publicly available data from a randomized controlled trial ( Results: Treatment produced large effects on depression at post-treatment (Cohen's Discussion: These findings confirm that this psychotherapy produces large, durable effects on treatment-resistant depression. However, the theorized sequential process - whereby reducing defensive functioning leads to improved affect regulation, which in turn alleviates depression - was not supported in the present data. Instead, the treatment appears to produce broad, simultaneous therapeutic change across multiple psychological domains. These exploratory findings suggest that understanding how psychotherapy works may require finer temporal measurement and observational methods that capture in-session processes.