# Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Parkinson’s Disease: A Randomized Trial

> **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637)
> **Publisher:** CED Clinic (https://cedclinic.com)
> **Canonical URL:** https://cedclinic.com/research/cbd-for-parkinsons-disease-randomized-controlled-trial/
> **Published:** 2026-09-17T12:06:25-04:00 | **Last Modified / Clinically Audited:** 2026-09-17T17:13:26-04:00
> **Clinical Summary:** A short randomised trial of a high-CBD, low-THC oral extract in 61 people with Parkinson's disease, a group who use cannabis often despite thin evidence.

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Participants with Parkinson’s disease scoring at least 20 on the motor MDS-UPDRS, and who tested negative for cannabis at baseline, took an oral sesame oil cannabis extract for two weeks, escalating to 2.5 mg/kg/day. Thirty-one were randomised to CBD/THC and 30 to placebo. The mean final dose was 191.8 mg CBD and 6.4 mg THC daily.

Motor MDS-UPDRS fell by 4.57 points (95% CI, -8.11 to -1.03; P = 0.013) on CBD/THC and by 2.77 (-4.92 to -0.61; P = 0.014) on placebo. The between-group difference – the number that matters – was -1.80 (-5.88 to 2.27; P = 0.379), which is not significant. Several assessments showed a strong placebo response.

Sleep, cognition and activities of daily living showed a treatment effect favouring placebo. Overall adverse events were mild but more frequent on the extract. Plasma levels at the final dose were 54.0 ng/mL CBD and 1.06 ng/mL THC. The authors are direct that a two-week duration and a strong placebo response limit what can be concluded, and call for longer trials.

 

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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).