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• Repeated supervised psilocybin sessions may reduce obsessive-compulsive disorder (OCD) symptoms. doi.org
  Mental Health OCD Psychedelic

  Obsessive-compulsive disorder (OCD) can remain highly disruptive even after standard treatments. Researchers tested whether repeated, carefully supervised sessions with psilocybin, a psychedelic compound naturally found in certain mushrooms, could safely reduce OCD severity in adults whose symptoms had not improved enough with prior guideline-based care.

  The study included 15 adults with moderate-to-severe OCD who received up to eight weekly treatment sessions in a controlled clinical research setting. During the first four weeks, participants were randomly assigned to high-dose (300 µg/kg) psilocybin, low-dose (100 µg/kg) psilocybin, or lorazepam, a comparison drug used as an active placebo. During the next four weeks, the 14 participants who continued in the study received weekly high-dose psilocybin sessions. Researchers measured symptoms with the Yale-Brown Obsessive Compulsive Scale, a clinician-rated OCD severity score ranging from 0 to 40, with higher scores indicating more severe symptoms, and also tracked safety and laboratory markers.

  • No serious adverse events were reported, and researchers found no emergent psychotic symptoms, no meaningful changes in suicide severity scores, and no clear changes in routine blood chemistry or blood count measures.
  • In the randomized first phase, both psilocybin doses led to lower next-day symptom scores than lorazepam, but only the high-dose group showed a statistically clear improvement over time. Across all participants, the average score was 28.6 at the start of the study and dropped to average next-day scores of 17.8 with high-dose psilocybin, 20.6 with low-dose psilocybin, and 25.9 with lorazepam.
  • After the 8-week treatment period, 11 of 15 participants met the study's response threshold, defined as at least a 35% drop in OCD severity score. Six of 15 participants met the remission threshold, defined as a score of 12 or lower.
  • At six months, benefits had faded for some participants but remained clinically notable in others: 8 of 14 participants still met the response threshold, and 3 of 14 met the remission threshold.
  • Participants with greater cumulative psilocybin exposure tended to show larger symptom reductions, but this analysis was exploratory and cannot prove the best dose schedule.

  Psilocybin is converted in the body into psilocin, which interacts with serotonin receptors involved in mood, perception, and cognitive flexibility. In OCD, symptoms often involve intrusive thoughts and repetitive behaviors that feel difficult to disengage from, so a temporary shift in rigid thinking patterns could plausibly help some patients interrupt those loops. Psilocybin may also influence brain networks that help people detect mistakes, repeat learned behaviors, and decide when to change course, which are all processes that can become overactive or inflexible in OCD.

  This was only a small study conducted under highly controlled clinical conditions, with extensive participant screening and trained facilitators supervising each session, so the findings should not be generalized to unsupervised use. However, if larger trials confirm these results, psilocybin treatment could emerge as a promising new option for people with OCD. In this clip, I discuss whether psilocybin could become a treatment option for depression.

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