Investigating the Therapeutic Effects of Psilocybin in Treatment-Resistant Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a complex disorder expressed as a variety of neurobiological symptoms, including anxiety, re-experiencing, hyperarousal, and avoidance symptoms, along with comorbidities such as anxiety, depression, and increased risk for self-medicating substance abuse. Currently, there are only two approved medications in the United States (US) for PTSD, paroxetine and sertraline. These selective serotonin reuptake inhibitors (SSRIs) have limited efficacy. Furthermore, there is a lack of efficacious pharmacotherapy for treatment-resistant PTSD; PTSD remains a chronic and sometimes debilitating condition. New research into other treatment options for PTSD are warranted.

Psychedelic medications, including psilocybin, have recently received breakthrough designation by the US Food and Drug Administration (FDA) for other psychiatric indications. Psilocybin has received breakthrough designation for treatment of depression. Research on psilocybin has shown that it facilitates fear extinction in mice and promotes neuroplasticity, increasing neurogenesis, spinogenesis and synaptogenesis. These properties may contribute to antidepressive and anxiolytic effects. Psilocybin also reduces activity in the amygdala during threat responses; decreased amygdala reactivity is correlated with positive mood. This is particularly relevant since individuals with PTSD showed increased reactivity in the amygdala, which may increase the ability to process traumatic memories. Although no formal clinical trials have yet investigated psychedelic substances for the treatment of PTSD, the available evidence warrants such an investigation. The present study aims to investigate the effect of psilocybin on treatment-resistant PTSD.