Enhancing Extinction Learning in Posttraumatic Stress Disorder With Brief Daily Imaginal Exposure and Methylene Blue: A Randomized Controlled Trial

Objective: The memory-enhancing drug methylene blue (MB) administered after extinction training improves fear extinction retention in rats and humans with claustrophobia. Robust findings from animal research, in combination with established safety and data showing MB-enhanced extinction in humans, provide a foundation to extend this work to extinction-based therapies for posttraumatic stress disorder (PTSD) such as prolonged exposure (PE).

Methods: Patients with chronic PTSD (DSM-IV-TR; N = 42) were randomly assigned to imaginal exposure plus MB (IE + MB), imaginal exposure plus placebo (IE + PBO), or waitlist (WL/standard PE) from September 2011 to April 2013. Following 5 daily, 50-minute imaginal exposure sessions, 260 mg of MB or PBO was administered. Waitlist controls received PE following 1-month follow-up. Patients were assessed using the independent evaluator-rated PTSD Symptom Scale-Interview version (primary outcome), patient-rated PTSD, trauma-related psychopathology, and functioning through 3-month follow-up.

Results: Both IE + MB and IE + PBO showed strong clinical gains that did not differ from standard PE at 3-month follow-up. MB-augmented exposure specifically enhanced independent evaluator-rated treatment response (number needed to treat = 7.5) and quality of life compared to placebo (effect size d = 0.58). Rate of change for IE + MB showed a delayed initial response followed by accelerated recovery, which differed from the linear pattern seen in IE + PBO. MB effects were facilitated by better working memory but not by changes in beliefs.

Conclusions: The findings provide preliminary efficacy for a brief IE treatment for PTSD and point to the potential utility of MB for enhancing outcome. Brief interventions and better tailoring of MB augmentation strategies, adjusting for observed patterns, may have the potential to reduce dropout, accelerate change, and improve outcomes.

Trial Registration: ClinicalTrials.gov identifier: NCT01188694