Study of Eye Movement Desensitization and Reprocessing (EMDR) Working Mechanism

EMDR (Eye Movement Desensitization and Reprocessing) is an exposure-based procedure for the treatment of patients with post-traumatic stress disorder (PTSD). Although the efficiency of EMDR-treatment is empirically proven, it remains unclear whether the bilateral stimulation triggered via eye movements has specific effects on treatment outcome. Hypothesis explaining the efficacy of the EMDR treatment are: focussing on the moving hand triggers an orientation reaction, and the duality of alertness focus during trauma exposition causes a distraction of the traumatic topic. Within a randomized controlled study 120 patients will be treated during 8 therapeutical sessions with EMDR with bilateral stimulation or one of two control conditions: EMDR without bilateral stimulation (eyes on a fixed, unmoving hand) and exposition without any visual stimuli to focus attention on. Primary outcome are scores on an interview measure for PTSD symptoms (Clinician Administered PTSD Scale (CAPS))as assessed pre-treatment and after treatment (max 8 sessions of psychotherapy). The following hypothesis are investigated in the study: 1. EMDR treatment with bilateral stimulation through eye movements will be followed significant larger reduction in CAPS compared with EMDR treatment without bilateral stimulation (specific treatment effect of eye movements) 2. EMDR with eyes fixed will be followed by a significant larger reduction in CAPS compared with EMDR without external focus (specific treatment effect of distraction)