The role of β-adrenergic stress hormones in Eye Movement Desensitization and Reprocessing (EMDR). Part I: the effects of β-adrenergic receptor antagonist propranolol on the plasticity of emotionally arousing episodic memories.

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.

Half of the participants will receive 40 mg of the beta-blocker propranolol and
half will receive a placebo. Of the three memories participants have to
retrieve during the pretest (and will be scored on VASs), one will be recalled
while making EM (recall + EM), one without EM (recall only), and one will not
be retrieved (no recall) during the intervention. During the posttest all three
memories will be retrieved again and scored on vividness/emotionailty.

This project encompasses a low risk study. The low dosage (40 mg) of
propranolol has minimal side-effects (see SPC and IB for an overview), and
serious adverse events are very unlikely. Participants are carefully screened
for contraindicative conditions and medication use. Another burden for the
subjects is that they have to invest some time (approximately 5 hours) in
participating in the study. The burdens of the test can be justified by the
clinical and scientific relevance of the study. Skin conductance, heart rate,
and currugator EMG measures are non-invasive. Participants can withdraw at any
time from the study.