Effects of Psilocybin on Speech Fluency, Struggle, and Brain Activity in People Who Stutter

This Phase 2a clinical trial is an open-label, single-group, within-subjects pilot study designed to evaluate the safety, feasibility, and preliminary efficacy of psilocybin as a therapeutic intervention for adults with developmental stuttering. This pilot study will assess whether further research to explore the potential benefits of psilocybin-assisted therapy for improving clinical outcomes in individuals who stutter, is warranted. The aims of this study include: * Aim 1: Assess the safety and feasibility of psilocybin as a therapeutic agent for stuttering. * Aim 2: Evaluate the effects of psilocybin on objective and subjective measures of stuttering severity, struggle, and well-being. * Aim 3: Explore the therapeutic neural mechanisms of psilocybin in stuttering.