Group Psilocybin-Assisted Therapy for Post-Traumatic Stress Disorder

This study is a community-informed, pragmatic, open-label, phase 1 clinical trial of group-format psilocybin-assisted therapy (GPAT) for individuals with post-traumatic stress disorder (PTSD). The primary objectives of this phase 1 study are to assess the safety and feasibility of (GPAT) for individuals with (PTSD) and to evaluate preliminary effects on PTSD severity. These will be assessed by the following outcome measures: * Proportion of participants completing the study protocol * Incidence of adverse events (AEs), serious adverse events (SAEs) and AEs of special interest using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 * Mean change in the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) and PTSD checklist for DSM-5 (PCL-5). The CAPS-5 and PCL-5 are based on the DSM-5 not the DSM-5-TR.