Impact of Psilocybin on Motor Function in Healthy Participants: A Phase 1, Randomised, Triple-Blind, Dose-Finding Study.
Chiranth Bhagavan, Olivia Carter, Glenn Nielsen et al.
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In 30 seconds
This phase 1, randomised, triple-blind, dose-finding study assessed the feasibility and safety of movement tasks during low-to-moderate-dose psilocybin in 13 healthy adults. Tasks were generally completed, with near-perfect scores on gross-motor and upper-limb measures. At 20 mg, one participant could not complete several tasks, and measures combining motor and cognitive performance worsened at 1.5 h; movement tasks were feasible up to 15 mg. Nausea (62%) and headache (54%) were the most common adverse events, with no serious adverse events or events related to task administration.
Key findings
- Movement tasks were feasible during psilocybin dosing up to 15 mg; one participant could not complete several tasks at 20 mg.
- At 20 mg and 1.5 h, Box and Block Test (Original) median scores were 57.5 [51.0-64.0], versus baseline 65.0 [60.0-67.0].
- Nausea occurred in 8 participants (62%) and headache in 7 (54%); no serious adverse events or task-related adverse events occurred.
- Participants and physiotherapists guessed the administered dose correctly 53% and 50% of the time, respectively.
Why it matters
The findings provide early evidence about whether movement assessments can be conducted during acute psilocybin effects, an important practical question for research into psychedelic-assisted rehabilitation. Gross-motor and upper-limb task performance remained high, while tasks involving motor and cognitive demands showed impairment at the highest dose and early assessment time. This distinction may inform the selection and timing of outcomes in future studies.
What to keep in mind
The study involved only 13 healthy adults, and its findings may not generalise to clinical populations. Outcomes were exploratory and summarised descriptively, with post hoc modelling.