Effects of Psilocybin on Context-Based Fear Learning, Extinction, and Reinstatement

Fear related mental disorders, including PTSD, stem from various environmental factors; part of this includes the context in which a trauma is experienced. Many treatments for PTSD exist, but they remain largely ineffective, especially over the long-term, so new treatment routes are constantly being explored. One of these new treatment options is the psychedelic agent psilocybin, which can increase positive mood, feelings of introspection, and learning via agonizing the serotonergic 5-HT(2A) receptor. The learning benefits from psilocybin could potentially be used in exposure therapy procedures for PTSD patients, where new, safe information is learned to replace the traumatic memories, lessening the mental and physiological symptoms of the condition. This study explored the efficacy of psilocybin on enhancing fear extinction in rodents that were conditioned to fear a certain context, similar to how an individual may learn to fear places similar to their trauma location. Despite some limitations, this study did show an early-trial enhancement of fear extinction after psilocybin injection, though the effect was short-lived, and did not impact later testing trials. More research will stem from these results, to potentially explore dose- or sex-dependent effects that may impact the efficacy of the psilocybin treatment