Brief Imaginal Exposure for PTSD: Trajectories of Change in Distress

Preliminary evidence shows that brief, condensed imaginal exposure only interventions can be effective in the treatment of PTSD, but we need to understand its mechanisms of action. Consistent with extinction learning and retrieval processes, the present study examined whether a pattern of between-session distress reduction observed during standard prolonged exposure (PE) therapy would be observed and predict outcome. Sixty-three patients with PTSD were enrolled in two clinical trials using our treatment protocol consisting of six daily 50-min sessions focusing on imaginal exposure and processing only. Individual patient trajectories of distress reduction were examined over the course of the five imaginal exposure sessions (Sessions 2-6). Overall, significant linear distress reduction was observed for anticipatory (d = 1.18), peak (d = 1.83), and ending imaginal exposure distress (d = 1.21). Consistent with extinction learning, the steeper slope of peak distress (d = 1.03) and end distress (d = 0.68) across imaginal exposure sessions strongly predicted decreases in PTSD symptoms. Distress reduction across sessions was predicted by higher baseline avoidance and hyperarousal but not reexperiencing symptoms. This condensed format of daily 50-min sessions without in vivo exposure may be operating via similar extinction learning processes as longer protocols. Our clinical observations suggest that the brief daily format may offer the advantage of allowing each session to build on the previous one to promote meaningful shifts in the retrieval of the trauma memory. Brief imaginal exposure and processing may be a viable option for PTSD patients in settings where brief interventions are needed. Understanding potential change processes and baseline predictors of change brings us closer toward precision medicine in treating PTSD.