Trauma-focused treatment for comorbid post-traumatic stress and substance use disorder

Trauma-focused treatments — psychotherapies that focus on trauma as a central component of treatment and use cognitive, emotional or behavioural techniques to facilitate the processing of a traumatic experience — are first-line interventions for post-traumatic stress disorder (PTSD). Although trauma-focused interventions are effective in treating PTSD and comorbid substance use disorder (SUD), these treatments are underused. Further, this comorbidity remains difficult to treat, with smaller treatment effect sizes and higher dropout rates than for PTSD alone. In this narrative Review, we examine the literature from clinical trials of trauma-focused treatment for patients with PTSD + SUD that might elucidate the attenuated treatment response and high rates of dropout. We first provide an overview of effective treatment for PTSD + SUD with respect to PTSD and substance use outcomes. We then review predictors of attendance and outcome in clinical trials evaluating trauma-focused treatments for PTSD + SUD. Next, we discuss possible strategies to improve response and reduce dropout in treatment for PTSD + SUD. Altogether, this Review provides the basis for recommendations for future research designed to improve treatment attendance and response and to increase the availability and reach of trauma-focused treatments for this population.