The working mechanisms of imagery rescripting and eye movement desensitization and reprocessing: Findings from a randomised controlled trial

We studied the mechanisms of eye movement desensitization and reprocessing (EMDR) and imagery rescripting (ImRs). We hypothesized that EMDR works via changes in memory vividness, that ImRs works via changes in encapsulated beliefs (EB), and that both treatments work via changes in memory distress. Patients (N = 155) with childhood-related posttraumatic stress disorder (Ch-PTSD) received 12 sessions of EMDR or ImRs. The vividness, distress, and EB related to the index trauma were measured with the Imagery Interview. PTSD severity was assessed with the Impact of Events Scale-Revised and the Clinician-Administered PTSD Scale for DSM-5. We conducted mixed regressions and Granger causality analyses. EMDR led to initially stronger changes in all predictors, but only for distress this was retained until the last assessment. No evidence for vividness as a predictive variable was found. However, changes in distress and EB predicted changes in PTSD severity during ImRs. These findings partially support the hypothesized mechanisms of ImRs, while no support was found for the hypothesized mechanisms of EMDR. Differences in the timing of addressing the index trauma during treatment and the timing of assessments could have influenced the findings. This study provides insight into the relative effectiveness and working mechanisms of these treatments.