A Pilot Randomized Placebo-Controlled Crossover Trial of Medicinal Cannabis in Adolescents with Tourette Syndrome

Introduction: Medicinal cannabis (MC) has potential therapeutic effects in Tourette Syndrome (TS), however there has been limited research in adolescent patients. This pilot study aimed to investigate the feasibility of conducting a randomized placebo-controlled crossover trial of MC in adolescents with TS. Method: This was a phase I/II double-blind, cross-over pilot study comparing MC with matched placebo in adolescents aged 12-18 years with TS. The active medication was Δ9-tetrahydrocannabinol (THC) 10 mg/mL and CBD 15 mg/mL in peppermint-flavored medium-chain triglyceride oil. The dose titration schedule was stratified into two participant weight bands: below 50 kg (max THC 10 mg/day) or ≥50 kg (max THC 20 mg/day). Each treatment phase lasted 10 weeks, with a 4-week washout period. Results: Ten adolescents were randomized (mean age 14.8 years, 50% male) and seven completed the full study protocol. Two adolescents discontinued due to adverse events (one on MC, one placebo) and one was lost to follow-up. The most common adverse event was dizziness (67%). There were no serious adverse events. Among actively enrolled participants, protocol adherence was excellent: study visits 100%, blood test completions 100%, and online questionnaire completion 97.6%. Medication adherence was acceptable in 63.6%. Parents reported a high degree of study design acceptability. On the Clinical Global Impression-Improvement scale, three participants were rated as much improved on MC compared with one on placebo at 10 weeks. Discussion: The findings suggest that the study protocol is feasible and acceptable to patients with TS and their families. A fully powered study is needed to evaluate the efficacy of MC in adolescent TS.