Cannabis Reduced Tic Urges but Not Tic Severity in Small Tourette Syndrome Trial

THC 10% did not significantly improve the primary outcome (video-rated tic severity, MRVTRS) but was significantly better than placebo on secondary measures: premonitory urges (PUTS), subjective distress (SUDS), and clinical global impression. THC plasma levels correlated with improvements across all measures. CBD 13% alone showed no significant effects. Most participants correctly identified whether they received cannabis or placebo.

Double-blind, randomized crossover trial with 12 adults with Tourette syndrome (9 completers). Each participant received single vaporized doses of THC 10%, THC/CBD 9%/9%, CBD 13%, and placebo at 2-week intervals. Tic severity rated by blinded video raters. Secondary measures included premonitory urges, distress, and global impression. Plasma cannabinoid levels measured.

Tourette syndrome has limited treatment options, and many patients report cannabis helps their tics. This controlled trial provides the first rigorous evidence for vaporized cannabis, showing benefits for the subjective experience of tics even if video-rated severity did not significantly change.

The disconnect between subjective improvement and objective tic ratings is clinically important. If cannabis reduces the urge to tic and the distress from tics without changing their frequency on video, it may still meaningfully improve quality of life for patients.

Very small sample of 9 completers limits statistical power. Single-dose design does not reflect sustained use. Most participants could tell cannabis from placebo, potentially unblinding the study. Crossover design may have carryover effects despite 2-week washout.