Mental health outcomes following a psilocybin session within Oregon’s state-regulated model: A naturalistic study

Under Oregon's regulated psilocybin program, adults who consumed an average of 27.8 mg of psilocybin showed significant improvements in depression, anxiety, and well-being 30 days after a session, including those concurrently using psychiatric medication. Of 88 participants (median age 43, 52% male, 64.8% with prior psychedelic experience), two reported symptoms of hallucinogen persisting perception disorder one day after the session, but none at 30 days. The findings suggest that legal psilocybin services can produce clinically meaningful mental health benefits.

Study at a glance

Abstract

Abstract Background In 2020, Oregon became the first U.S. state to establish a regulated framework for adults to access psilocybin services using naturally-derived mushroom products. No studies have examined mental health outcomes among individuals receiving psilocybin in this context. Aims To evaluate changes in self-reported symptoms of depression, anxiety, and well-being 30-days post-psilocybin session under the Oregon state-regulated model , and document session-related adverse events and doses consumed. Methods This was a naturalistic study (March 2024-April 2025) among adults ≥21 years participating in a legal psilocybin services program. Online surveys were completed pre-session, 1-day, and 30-days post-session. Primary outcomes were change in depression, anxiety, and well-being symptoms pre-session to 30-days post-session evaluated using linear mixed-effects models (random effect: timepoint; fixed effects: sex, concurrent psychiatric medication use, age, session dose [total psilocybin equivalents, TPE, mg: psilocybin mg + 1.39 * psilocin mg]). Adverse events (e.g., hallucinogen persisting perception disorder [HPPD]) were assessed at 1-day and 30-days post-session. Results Participants (n=88; median age 43 years; 52% male) were predominantly Oregon residents (53.4%), psychedelic-experienced (64.8%), and concurrently using psychiatric medication (46.6%). All outcomes improved significantly at 30-days post-session (p<0.001), including in sensitivity analyses stratified by concurrent psychiatric medication usage (p<0.001 all outcomes, both groups). Two participants (2.3%) reported symptoms consistent with HPPD at 1-day post-session, but none at 30-days. Mean dose was 27.8 mg (SD 8.2) TPE. Conclusions Psilocybin sessions delivered under the Oregon regulatory model were associated with clinically meaningful improvements in depression, anxiety, and well-being 30-days post-session, supporting therapeutic effectiveness of legal psilocybin services.