Norton, L. G., Harmsen, C. R., Corderio, K., Baranowsky, A., & Muller, R. T. (2024). Depression symptom changes in triphasic trauma therapy: Initial findings from a community-based observational study. Journal of Psychotherapy Integration. https://doi.org/10.1037/int0000335

This observational naturalistic study examined depression symptom change over the course of trauma-focused therapy. Depression symptom change was measured in 39 participants over the course of a triphasic trauma therapy called trauma practice (TP). Self-report measures were administered upon therapy initiation, following each therapy phase, and then at follow-up. Results demonstrated statistically and clinically significant improvements in depression symptoms following treatment. 

Langdon, G. A., Harmsen, C. R., Cordeiro, K., Baranowsky, A., & Muller, R. T. (2025). Trauma‐Related Symptom Improvement in Multimodal Triphasic Trauma Therapy: Findings From a Community‐Based Study. Clinical Psychology & Psychotherapy, 32(2), e70055. https://doi.org/10.1002/cpp.70055

This single-arm effectiveness study explored changes in trauma-related symptoms—including dissociation, depression, anxiety, sexual issues and sleep disturbances—throughout a multimodal, phased trauma intervention, to explore treatment response in real-world settings with varied populations and complex clinical presentations, as well as varied degrees of clinician experience. Participants completed self-report measures at the start of therapy, after each therapy phase and 6 months post treatment. The findings revealed statistically and clinically significant reductions in symptoms across all measured domains.

Harmsen, C. R., Salisbury, M., Cordeiro, K., Rependa, S., Baranowsky, A., & Muller, R. T. (2025). Posttraumatic symptom improvement in trauma practice triphasic therapy: Preliminary findings from a multisite, community-based setting. Psychological Trauma: Theory, Research, Practice, and Policy. https://doi.org/10.1037/tra0002029

This study examined the effectiveness of trauma practice (TP), a multimodal, triphasic approach to trauma therapy, within a community-based setting, including phase-linked effects on therapeutic outcomes. Posttraumatic symptoms (Post-Traumatic Stress Disorder Checklist for Diagnostic and Statistical Manual of Mental Disorders, fifth edition) and trauma-related distress (Trauma Symptom Checklist [TSC-40]) were measured at baseline, after each phase, and at 6 months posttherapy. Mixed effects models, nested by participants and clinician education level, showed significant decreases in posttraumatic symptoms and trauma symptom distress.

Harmsen, C. R., Langdon, G. A., Cribbie, R. A., Baranowsky, A. N. N. A., & Muller, R. T. (2026). An Investigation of a Community-Based Phase-I Online Group Trauma Intervention. International Journal of Group Psychotherapy, 1-29. https://doi.org/10.1080/00207284.2025.2600104

This study examined the feasibility of online group therapy for trauma survivors. Community-based participants self-referred for an eight-week psychoeducational, skills-based trauma therapy group, which was offered via secure video conferencing. Mixed effects models showed significant overall PCL-5 reductions, with clinically meaningful change during treatment. PTSD symptom subtypes as measured by the PCL-5 (reexperiencing, avoidance, negative cognition/mood, arousal) also improved.

Harmsen, C. R., Cordeiro, K., Rependa, S., Baranowsky, A., & Muller, R. T. (2026). Online Group Trauma Therapy in a Community Setting: Group Climate and Satisfaction in Relation to Treatment Response. International Journal of Group Psychotherapy, 1-28. https://doi.org/10.1080/00207284.2025.2602009

A free, skills-based trauma therapy program was delivered online to 80 individuals in an urban setting. Trauma-related symptoms were measured pre- and postgroup using the PCL-5 and TSC-40. Treatment satisfaction emerged as a significant predictor of symptom reduction. Notably, satisfaction with the practicality and real-world applicability of the group’s content was closely linked to improved outcomes.