Study: Oregon psilocybin services linked to major drops in anxiety, depression and PTSD

PORTLAND, Ore. (KTVZ) -- A study led by Oregon Health & Science University found that participants using state-regulated psilocybin services experienced substantial reductions in symptoms of anxiety, depression and post-traumatic stress disorder, with low rates of severe adverse events.

The findings, published today in the journal JAMA Network Open, mark the first multisite evaluation of Oregon's regulated psilocybin program since state voters legalized nonmedical access.

Oregon voters approved a nonmedical wellness model in 2020, opening licensed access to mind-altering mushrooms for adults ages 21 and older starting in 2023. The new study evaluated 346 participants who completed a single psilocybin session across 24 licensed service centers between November 2024 and June 2026.

At one month after their psilocybin session, 91.5% of participants reported that they benefited from the experience. Additionally, 64.9% ranked the session among the 10 most meaningful experiences of their lives. At three months, participants reported decreases in moderate-to-severe symptoms of depression, anxiety and post-traumatic stress disorder, alongside overall improvements in mental well-being. Response rates remained high, with 90% of participants continuing to report through the three-month mark.

Four participants using psilocybin for the first time experienced adverse behavioral reactions that required medical attention. No participants reported serious physical health events, though seven people described the experience as harmful at the three-month follow-up. Lead author Dr. Todd Korthuis, professor of medicine at the OHSU School of Medicine, addressed the safety outcomes of the study.

“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 use.”

Unlike previous clinical trials where all participants had moderate to severe depression, only about half of the Oregon study participants reported moderate to severe depression prior to their session. Korthuis noted that study participants may have been healthier overall than clinical trial subjects. “This may be a reflection of clients who were healthier overall than clinical trial participants,” Korthuis said. “The results demonstrate it's safe for people receiving state-regulated psilocybin experiences.”

Korthuis emphasized that psilocybin is not appropriate for individuals with psychosis, bipolar disorder or who are pregnant. “Just because something isn't a medical model doesn't mean you can't have mental health benefits,” Korthuis said. “Still, people with serious mental health or medical conditions should talk with their health care providers before seeking services.”

Senior co-author Dr. Adrianne R. Wilson-Poe, a scientist at Legacy Research Institute and co-director of the Oregon Psychedelic Evaluation Nexis, highlighted the significance of tracking real-world outcomes. “This paper is going to be cited for decades,” Wilson-Poe said. “This is the first large-scale study to monitor the safety and mental health symptoms of real people in the real world.”

The survey platform developed for the study was approved by OHSU's Institutional Review Board and has expanded to Colorado, which also approved regulated psilocybin services. Wilson-Poe explained that the platform can measure outcomes in other states. “It can give us an apples-to-apples comparison,” Wilson-Poe said.

OHSU President Dr. Shereef Elnahal, former undersecretary of health in the U.S. Department of Veterans Affairs, noted the relevance of the findings for federal and state officials. “These early results reveal psilocybin's potential to improve health in people accessing these services here in Oregon,” Elnahal said. “The study also provides important insight for policymakers considering programs that permit psychedelics for the treatment of mental health conditions, including for PTSD and substance use disorders affecting America's military veterans.”

Data from the Oregon Health Authority shows that more than 20,000 people have accessed licensed psilocybin services in the state. However, costs ranging from hundreds to thousands of dollars per session present a barrier to access and several Oregon counties have opted out of allowing service centers due to safety concerns. Korthuis noted that the study findings could inform those local decisions. “Those counties may find this data reassuring, as may policymakers considering similar measures in other states,” Korthuis said.

Researchers will use a $3.3 million, five-year federal grant awarded earlier this year to study psilocybin's effect on reducing illicit substance use among clients at licensed Oregon service centers. Study findings are also scheduled for presentation today at the Psychedelic Innovation Summit in Portland, co-hosted by OHSU and the Healing Advocacy Fund.