95% of Oregon Psilocybin Study Participants Saw Improvements in Depression, PTSD
By Ashleigh Hollowell | August 19, 2026
Image by Michael M from Pixabay | CC0
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Adverse effects were found to be uncommon among a cohort of nearly 350 adults who participated in the first-ever U.S. state-regulated psilocybin study in Oregon. Not all participants in the study were seeking out psilocybin for mental health treatment. Still, 92.2% reported improvements in depression, anxiety, and overall mental wellbeing at one month after receiving treatment, researchers at the Oregon Health and Science University found.
Oregon became the first state in the nation to legalize psilocybin in 2020. That allowed state researchers and providers to begin developing therapeutic guardrails.
Since voters approved a recreational model for psilocybin, rather than a medical one that moved into recreational like the path cannabis took, establishing clinical safety to evaluate its use for those purposes was crucial.
“Just because something isn’t a medical model doesn’t mean you can’t have mental health benefits,” said Dr. Todd Korthuis, the study’s lead author and a professor of medicine at Oregon Health and Science University. “Still, people [with] serious mental health or medical conditions should talk with their healthcare providers before seeking services.”
During the Oregon Health and Science University-led study, participants were given a psilocybin dose in a controlled environment by a session facilitator who also oversaw safety protocols. Patients reported depression and anxiety symptoms on the PHQ-9 and GAD-7 scales and shared information about mental wellbeing overall, life satisfaction, harms, and service satisfaction.
Overall, 90.2% of patients still reported beneficial experiences. Only four (1.2%) experienced adverse behavioral reactions that required medical attention. Seven participants (2.3%) reported their experience being “harmful” after three months. But at three months, 95% felt a decrease in moderate-to-severe depression, anxiety, PTSD, and an increase in overall mental wellness and life satisfaction. Almost 60% "ranked the experience as among the top 10 most meaningful of their lives," according to the research.
Zero participants reported a serious event or adverse impact on their physical health overall.
“Safety was very similar to what we’ve seen with psychedelics in clinical settings,” Korthuis said. “That’s important because there was a big question around whether or not safety in carefully controlled psilocybin clinical trials would translate into real-world..."