4 - (SYM 86) The Efficacy of Written Exposure Therapy in Reducing PTSD Symptoms and Mental Contamination in Survivors of Sexual Victimization: Preliminary Results from a Single-case Experimental Study

Background: Mental contamination (MC) refers to the experience of pollution in the absence of a contaminant. MC has been robustly positively correlated with PTSD symptoms among survivors of sexual victimization and has been proposed as a potential treatment target among this population. However, there is limited research on whether MC is responsive to interventions for PTSD. The present study conducted a preliminary analysis of findings from an ongoing trial assessing whether Written Exposure Therapy (WET) reduces PTSD symptoms and trauma-related MC in survivors of sexual victimization using a multiple baseline single-case experimental design (SCED).

Method: Individuals who met diagnostic criteria for current PTSD and endorsed trauma-related MC were randomized to a three- or five-week baseline period and completed weekly self-report assessments of PTSD (PCL-5) symptoms and MC (PEMC) during the baseline period, across five sessions of WET, and for three weeks post-treatment. Participants (n = 2; one 3-week and one 5-week baseline) completed all study procedures; exhibited stable or worsening PTSD symptoms and MC between the first and last two baseline assessments (≤ 12-point decrease on the PCL-5 and ≤ 6-point decrease on the PEMC); and exceeded the cutoff scores for probable PTSD diagnosis (PCL-5 ≥ 33) and moderate MC (PEMC ≥ 20) during the baseline period. In line with analytic norms for SCEDs, we conducted a visual inspection analysis of weekly scores to evaluate the degree and rate of change throughout the baseline, treatment, and post-treatment periods. We also computed 95% confidence intervals (CIs) around the change scores for each participant during the baseline (last baseline – first baseline), treatment (last session – last baseline), and follow-up (last follow-up – last session) periods by calculating a standard error of the difference score and multiplying it by 1.96 for each measure. Changes were considered reliable if the CI did not contain zero. 

Results: Both participants exhibited stable or worsening symptoms during the baseline period and reliable improvement in both PTSD symptoms and MC during treatment. There were no significant changes in PTSD symptoms or MC during follow-up, suggesting that these gains were maintained during the post-treatment period. 

Conclusion: Findings provide preliminary support for the utility of WET in addressing both PTSD symptoms and trauma-related MC among survivors of sexual victimization. Potential clinical implications and avenues for future research will be discussed.