Le blocage de la reconsolidation des souvenirs, une avenue possible pour le traitement du trouble de stress post-traumatique?

This dissertation aims at exploring the efficacy of a new treatment for posttraumatic stress disorder (PTSD). The treatment was developed in accordance with an emerging theory in neuroscience, the reconsolidation theory, and it consists in six short reactivation sessions of a traumatic memory under the influence of propranolol (a ß-blocker), with patients suffering from longstanding PTSD. This dissertation includes five chapters. Chapter I is the introduction, it includes a discussion on the following topics : definition and prevalence of PTSD,empirically validated treatments in the field, memory theories, etiology of PTSD, studies on consolidation and reconsolidation, pharmacokinetics of propranolol and its mechanism of action in reconsolidation, and the objectives of the dissertation. Chapter II is a critical literature review on reconsolidation theory. We discuss some of the contradicting findings in reconsolidation, as some researchers have reported negative results in the field. We address the possibility to reconcile these discrepancies,within the scope of evaluating the validity of the theory. We also discuss a series of criterion which could provide guidance in differentiating reconsolidation from other processes. We conclude that reconsolidation theory seems valid, although more research is needed in order to shed light on some negative results that were published in the past. Chapter III is an open label trial comprising six sessions of treatment (trauma reactivation under propranolol) with 42 patients suffering from chronic PTSD. At a three-month follow-up, we report that patients have a 41% - 56% reduction in PTSD symptoms, and that 31 / 42 patients no longer meet the diagnostic threshold for PTSD. In comparison, only 2 / 25 patients from the control group (assessments only) don’t meet the diagnostic threshold for PTSD. In the treatment group, effect sizes (Cohen’s d) range between 1.32 -2.19. Chapter IV follows on the previous chapter’s study, and aims at identifying predictors of treatment outcome (i.e., predictors of the improvement in PTSD symptoms), and whether patients also improve in health domains other than PTSD. We report that women improve more than men during the treatment, but that other factors such as borderline personality severity traits or type of trauma (childhood versus adulthood) do not influence treatment outcome. Patients also improve in diverse health domains during the treatment; they have a better quality of life, less depressive symptoms, less intense negative emotions in daily life and during trauma recollection. Chapter V contains a general discussion and a conclusion. We summarize and interpret the results, we explore alternative hypotheses to the clinical improvement as well as future research directions. We conclude that this treatment yielded interesting results in our sample of patients suffering from chronic PTSD. However, our methodology (open label study) doesn’t provide any information on the mechanism of action of the treatment used in this dissertation, i.e. whether the clinical improvement was caused or not by reconsolidation blockade.

Keyphrases: Reconsolidation, Propranolol, Extinction, Posttraumatic stress disorder, Treatments, Memory, Gender effects, Exposure