EMDR, an effectiveness as miraculous as it is mysterious

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EMDR, an effectiveness as miraculous as it is mysterious
Treating post-traumatic stress disorder with EMDR has been proven to be effective, but the mechanisms behind this therapeutic technique remain poorly understood. Three researchers from the University of Freiburg suspect that working memory plays a crucial role.

A person who has been assaulted is at high risk of experiencing psychological trauma. This can manifest itself through anxiety attacks, flashbacks or other physical or emotional symptoms, but therapeutic solutions exist! In 1987, Francine Shapiro invented EMDR (Eye Movement Desensitization and Reprocessing). The American psychologist then noticed, almost by chance, that she was able to remove the emotional charge of the negative thoughts that assailed her by making repetitive eye movements. Surprised, she then tested this technique on volunteers, then on Vietnam war veterans suffering from post-traumatic stress disorder. The effects of EMDR proved to be astonishing, even if the mechanisms involved remain somewhat mysterious.

Limitation of the processor?
Dany Laure Wadji, Chantal Martin Sölch and Valérie Camos, from the Department of Psychology at the University of Fribourg, wanted to test the working memory hypothesis. This hypothesis postulates that the EMDR session, by involving a double task, that of recalling a traumatic memory and simultaneously performing eye movements, would have the effect of saturating the working memory. It is this competition for limited memory resources that would cause a loss of vividness in traumatic memories. The therapist asks the patient to concentrate on a memory while imposing a secondary task, explains Chantal Martin-Soelch. By reducing his attention, this secondary task would cause an incomplete recovery of the memory, which would have the consequence of reducing the level of emotion.

Method of work
To test this hypothesis, the researchers from Fribourg used data from eleven published studies on the subject, which they divided into two categories, the first involving participants with post-traumatic stress disorder, the second involving participants without such disorder. The results show that the dual-task task allows a greater reduction in the emotional intensity of a memory than when participants are subjected to a single task (for example, focusing only on a painful memory, but without having to make eye movements). These results suggest that the working memory hypothesis is relevant," says Dany Laure Wadji. When an individual recalls a traumatic memory while performing a secondary task, this diverts his or her attention and leads to a reduction in emotionality, a better digestion of a trauma in short, and also a reduction in possible symptoms.’

Clinical implications
The Fribourg analysis confirms that any task requiring attentional resources, whether visual or auditory, could promote the desensitization of a traumatic memory. However, we must be cautious about the level of difficulty of the distractive task," warns Valérie Camos, "and also bear in mind that the changes induced by EMDR can disappear over time, as two studies have shown." Confirming the hypothesis of the role of working memory, this study opens the way to future research likely to examine this mechanism on a larger scale and in a clinical setting.

Read the article published in BMC Psychology