High-Dose CBD Was Neither Effective Nor Toxic for Huntington's Disease in a Controlled Trial
In a double-blind crossover trial, CBD at approximately 700 mg/day for six weeks produced no significant improvement in Huntington's disease symptoms compared to placebo, but was also well tolerated with no safety concerns.
Quick Facts
What This Study Found
Based on encouraging preliminary findings, researchers conducted a rigorous controlled trial of CBD in 15 Huntington's Disease patients who were not taking neuroleptic medications.
Patients received either oral CBD (10 mg/kg/day, averaging about 700 mg/day) or placebo (sesame oil) for six weeks each in a double-blind, randomized crossover design. The primary outcome was chorea severity, the involuntary jerking movements characteristic of HD.
CBD produced no significant differences from placebo on chorea severity or any other therapeutic outcome measure. It was also not toxic: clinical lab tests, a cannabis side effect inventory, and other safety measures showed no significant differences from placebo.
Plasma CBD levels were consistent across the six weeks (mean range 5.9 to 11.2 ng/mL), confirming patients were absorbing the drug. The conclusion was straightforward: at this dose and duration, CBD was neither helpful nor harmful for HD.
Key Numbers
15 patients. CBD dose: 10 mg/kg/day (approximately 700 mg/day). Duration: 6 weeks per phase. Plasma CBD: 5.9 to 11.2 ng/mL. No significant differences on any outcome (P > 0.05).
How They Did This
Double-blind, randomized crossover trial in 15 neuroleptic-free Huntington's Disease patients. CBD (10 mg/kg/day) and placebo (sesame oil) were each administered for 6 weeks. Weekly assessments included chorea severity, therapeutic outcomes, side effects, clinical lab tests, and plasma CBD levels by GC/MS.
Why This Research Matters
This was one of the first rigorous controlled trials of CBD for a neurodegenerative disease. While the negative result was disappointing, it was scientifically important: it demonstrated that CBD does not universally benefit all neurological conditions and established a safety profile at high doses.
The Bigger Picture
This negative result is a useful counterpoint to the tendency to assume CBD helps all neurological conditions. HD involves specific pathology (striatal neuron degeneration) that may not respond to CBD's mechanism of action. The study's well-tolerated safety profile at 700 mg/day, however, supported future CBD research in other conditions.
What This Study Doesn't Tell Us
Fifteen patients is a small sample. Six weeks may be too short to detect slowly developing benefits. The crossover design assumes no carryover effects. Plasma CBD levels were relatively low despite high oral doses, suggesting poor bioavailability.
Questions This Raises
- ?Would longer treatment duration produce different results?
- ?Would higher plasma levels (achievable via different formulations) be effective?
- ?Why were preliminary findings encouraging but the controlled trial negative?
Trust & Context
- Key Stat:
- No significant differences between CBD (700 mg/day) and placebo on any HD outcome
- Evidence Grade:
- A well-designed double-blind, randomized crossover RCT, but with only 15 patients. The rigorous design adds confidence to the negative finding.
- Study Age:
- Published in 1991. CBD research has expanded enormously, but large-scale trials for neurodegenerative diseases remain limited.
- Original Title:
- Controlled clinical trial of cannabidiol in Huntington's disease.
- Published In:
- Pharmacology, biochemistry, and behavior, 40(3), 701-8 (1991)
- Authors:
- Consroe, P(4), Laguna, J, Allender, J, Snider, S, Stern, L, Sandyk, R, Kennedy, K, Schram, K
- Database ID:
- RTHC-00039
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Did CBD help Huntington's Disease?
No. In this controlled trial, CBD at approximately 700 mg/day for six weeks produced no significant improvement in chorea or any other HD symptom compared to placebo.
Was CBD safe at this dose?
Yes. At approximately 700 mg/day for six weeks, CBD produced no significant side effects or laboratory abnormalities compared to placebo.
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Cite This Study
https://rethinkthc.com/research/RTHC-00039APA
Consroe, P; Laguna, J; Allender, J; Snider, S; Stern, L; Sandyk, R; Kennedy, K; Schram, K. (1991). Controlled clinical trial of cannabidiol in Huntington's disease.. Pharmacology, biochemistry, and behavior, 40(3), 701-8.
MLA
Consroe, P, et al. "Controlled clinical trial of cannabidiol in Huntington's disease.." Pharmacology, 1991.
RethinkTHC
RethinkTHC Research Database. "Controlled clinical trial of cannabidiol in Huntington's dis..." RTHC-00039. Retrieved from https://rethinkthc.com/research/consroe-1991-controlled-clinical-trial-of
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.