Psilocybin Motor Function Changes With Higher Doses

PSILOCYBIN motor function remained largely preserved through 15 mg in healthy adults, while 20 mg impaired complex performance.

A Phase 1, randomized, triple blind dose finding study evaluated whether healthy adults could safely complete movement tasks during the acute effects of low to moderate psilocybin doses. Thirteen participants, with a median age of 33 years, received three doses in randomized order: either 5 mg, 10 mg, and 15 mg, or 10 mg, 15 mg, and 20 mg. Movement assessments were performed 1.5, 3, and 4.5 hours after dosing.

Psilocybin Motor Function Remained Feasible Through 15 mg

All participants completed the primary movement assessments at 5 mg, 10 mg, and 15 mg. At 20 mg, one participant was unable to complete several tasks during peak drug effects, including both primary measures at 3 hours.

Across the cohort, gross motor performance remained near ceiling on the de Morton Mobility Index and Functional Movement Exploration, while upper limb performance on the Action Research Arm Test also changed little. Reaction time showed no consistent dose related pattern.

The clearest impairments appeared in tasks that combined motor performance with additional cognitive demands. At 20 mg, Box and Block Test scores worsened during peak effects, and Digit Symbol Substitution Test performance was significantly impaired at both 1.5 and 3 hours. The investigators noted that these findings may indicate a threshold at which higher order motor and cognitive coordination becomes more difficult.

Lower Doses Showed Signals Worth Further Study

Some exploratory measures improved after lower doses once peak psychedelic effects had subsided. Box and Block Test performance improved at 5 mg and 10 mg at 4.5 hours, while Digit Symbol Substitution Test scores improved at 10 mg at the same timepoint. The authors cautioned that practice effects may have contributed.

No serious adverse events or adverse events related to movement task administration occurred. Nausea affected 62% of participants and headache 54%, while blood pressure and heart rate increased transiently without requiring acute intervention.

For clinicians, the findings provide early feasibility data for future studies combining psilocybin with physical rehabilitation. The results suggest that doses up to 15 mg may allow meaningful movement task participation in healthy adults, whereas 20 mg may compromise more complex tasks requiring simultaneous motor and cognitive engagement. The small sample and healthy, younger study population limit generalizability to patients with neurologic disease, frailty, or comorbidities.

Reference
Bhagavan C et al. Impact of Psilocybin on Motor Function in Healthy Participants: A Phase 1, Randomised, Triple-Blind, Dose-Finding Study. CNS Drugs. 2026;DOI:10.1007/s40263-026-01326-4.

Featured Image: zhukovvvlad on Adobe Stock.