Psilocybin for Treatment of Prolonged Grief Disorder: An Open-Label Feasibility Study Protocol

Prolonged grief disorder (PGD) affects approximately 10% of bereaved individuals and is now formally recognized in both the DSM-5-TR and ICD-11. Despite its prevalence, PGD often responds poorly to traditional therapeutic approaches. This manuscript outlines the protocol for an early-stage open-label feasibility trial investigating the use of psilocybin, a psychedelic compound, in treating PGD in adults, with a focus on young adults. The study will involve 20 participants diagnosed with PGD. Each participant will undergo a structured therapeutic process that includes a preparatory session, a single 25 mg dose of psilocybin, and post-session integration. Throughout the study, participants will be monitored via symptom assessments, including qualitative and quantitative data, with the main aims related to safety, feasibility and acceptability. Functional MRIs will be obtained pre- and post-dosing and collected during a standardized grief-elicitation methodology. Key outcome measures include changes in the severity of PGD and trauma symptoms, cognitive flexibility, openness to experience, meaning in life and subjective experiences during the psilocybin session. Neural activity will also be evaluated through fMRI to better understand the neurobiological effects of the treatment. This research represents one of the first clinical protocols specifically focused on the potential of psilocybin for treating PGD. The goal is to assess feasibility and safety while laying the groundwork for future randomized controlled trials.