Unravelling the underlying mechanisms of Eye Movement Desensitization and Reprocessing (EMDR) therapy: The effects of beta-blocker Propranolol on EMDR effectiveness.

Eye Movement Desensitization and Reprocessing (EMDR) is a widely used, effective psychological treatment for posttraumatic stress disorder (PTSD). Its core intervention is that patients recall trauma memories while simultaneously making lateral eye movements. It is largely unknown how EMDR works, however, much evidence has been obtained for the working memory hypothesis. This hypothesis comprises that both recalling traumatic memories and making eye movements (EM) tax working memory (WM), which has limited capacity. Simultaneously performing both tasks leads to a competition for WM, rendering the traumatic memories less vivid and emotional. When memories are recollected they re-enter a labile state and become malleable and, because of this, the traumatic memory is overwritten by the memory that is blurred by EM. Emotional material is better (re) consolidated than emotional neutral material, i.e., it is prioritized and is (re) consolidated more vividly and in greater detail. This is caused by the release of noradrenaline (NA). In EMDR emotional material is recollected and reconsolidated. Therefore, EMDR might work because of NA release, i.e., NA enhances the reconsolidation of the blurred emotional memories.



The goal of the present study is to investigate whether the blockade of NA-transmission by beta-antagonist propranolol reduces the common EMDR effects (reduced vividness/emotionality of emotional memories) in order to find out if NA-release (evoked by the emotionality of the memories) plays an important role in the blurring of traumatic memories during EMDR.



The proposed study will use a double-blind, placebo-controlled, experimental, repeated measures design, with medication group (placebo, propranolol) as between subjects independent variable, condition (recall + EM, recall only, no recall) and time (pretest, posttest-1, posttest-2) as within subjects independent variables, and VAS-rated vividness and emotional arousal, and physiological response (heart rate, skin conductance and facial electromyography (EMG)) as dependent variables.

The goal of the present study is to investigate whether the blockade of NA-transmission by beta-antagonist propranolol reduces the common EMDR effects (reduced vividness/emotionality of emotional memories) in order to find out if NA-release (evoked by the emotionality of the memories) plays an important role in the blurring of traumatic memories during EMDR.

Direct post-test and 24h hour follow-up.

1. Propranolol 40 mg or placebo;

2. Memory recall + eye movements, memory recall only.