# Tetrahydrocannabinol and Cannabidiol in Tourette Syndrome

> **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637)
> **Publisher:** CED Clinic (https://cedclinic.com)
> **Canonical URL:** https://cedclinic.com/research/thc-for-tourette-syndrome-randomized-controlled-trial/
> **Published:** 2026-09-17T12:06:25-04:00 | **Last Modified / Clinically Audited:** 2026-09-17T17:13:04-04:00
> **Clinical Summary:** A crossover trial in which 22 people with severe Tourette syndrome took both an oral THC/CBD oil and a placebo, six weeks each.

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This was a double-blind crossover trial: each participant took escalating doses of an oral oil containing 5 mg/ml THC and 5 mg/ml CBD for six weeks and placebo for six weeks, separated by a four-week washout. Twenty-two participants with severe Tourette syndrome were enrolled.

The primary outcome was the total tic score on the Yale Global Tic Severity Scale. Reduction at week 6 relative to baseline was 8.9 (SD 7.6) on active treatment versus 2.5 (SD 8.5) on placebo. A linear mixed-effects model found a significant treatment-by-visit interaction (coefficient -2.28; 95% CI, -3.96 to -0.60; P = 0.008).

Secondary outcomes suggested possible benefit for impairment, anxiety and obsessive-compulsive symptoms. Against that, eight participants reported cognitive difficulties during active treatment – slowed mentation, memory lapses, poor concentration – compared with headache as the most common complaint on placebo. With 22 participants, these estimates carry wide uncertainty.

 

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### Verification & Medical Governance

- **Lead Clinical Author:** Benjamin Caplan, MD
- **Credentials:** Board Certified in Family Medicine (ABFM), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House).
- **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`).
- **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/).
- **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637).
- **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).