Effects of timing and type of trauma-focused treatment on psychosocial functioning: secondary outcomes from a randomized controlled trial in patients with co-occurring substance use disorder and posttraumatic stress disorder

Patients with co-occurring posttraumatic stress disorder (PTSD) and substance use disorder (SUD) often experience additional psychosocial difficulties, including emotion dysregulation, interpersonal problems, and trauma-related guilt and shame. Evidence on optimal timing and type of trauma-focused treatment remains limited, particularly for psychosocial outcomes beyond PTSD and SUD-severity. This study examined secondary outcomes from a randomized controlled trial (RCT) comparing Prolonged Exposure (PE), Eye Movement Desensitization and Reprocessing (EMDR), and Imagery Rescripting (ImRs), delivered simultaneously with or sequentially to SUD-treatment. Aims were to evaluate (1) added effects of trauma-focused treatment at 3-month follow-up, and over 9 months (2) simultaneous versus sequential delivery, and (3) differences between PE, EMDR, and ImRs. METHOD: 209 patients were randomly allocated to PE, EMDR, or ImRs; 75% received simultaneous and 25% sequential treatment. Assessments were conducted at baseline, 3-, 6-, and 9-month follow-up. Outcomes included psychological distress, emotion dysregulation, interpersonal problems, trauma-related guilt and shame, and anger control. Multiple linear regression and linear mixed models were used; missing data were handled using multiple imputation. RESULTS: Adding EMDR or ImRs to SUD-treatment resulted in improvements in several psychosocial outcomes at 3-month follow-up, whereas PE did not. Simultaneous treatment yielded greater improvements than sequential treatment, largely due to differences before PTSD-treatment initiation in the sequential condition. No significant differences emerged between treatment types. CONCLUSIONS: Trauma-focused treatments, particularly EMDR and ImRs, are effective add-ons to SUD-treatment for improving psychosocial outcomes. Simultaneous delivery may be preferable due to faster benefits. This study supports shared-decision making regarding timing and type of PTSD-treatment.