CBD/THC extract showed no clear benefit for Parkinson's motor symptoms in a short trial, and may have worsened sleep and cognition
A two-week RCT of 61 Parkinson's patients found that a high-CBD/low-THC cannabis extract did not significantly improve motor symptoms compared to placebo, and may have worsened cognition and sleep.
Quick Facts
What This Study Found
Motor scores improved in both the CBD/THC group (4.57-point reduction) and placebo group (2.77-point reduction), but the between-group difference was not statistically significant (p = 0.379). Sleep, cognition, and daily living assessments showed effects favoring placebo.
Key Numbers
61 participants randomized. Mean final dose: 191.8 mg CBD + 6.4 mg THC daily. Motor improvement: 4.57 points (CBD/THC) vs. 2.77 points (placebo), difference not significant (p = 0.379). CBD plasma level at final dose: 54.0 ng/mL.
How They Did This
Double-blind RCT of 61 participants with Parkinson's disease randomized to CBD/THC oral solution (n=31) or placebo (n=30) for two weeks. Final dose averaged 192 mg CBD and 6.4 mg THC daily. Used MDS-UPDRS motor scores as the primary outcome.
Why This Research Matters
Cannabis use is common among Parkinson's patients despite limited evidence. This trial provides some of the first rigorous data, and the results suggest high-CBD/low-THC formulations may not help motor symptoms and could have downsides.
The Bigger Picture
The strong placebo response in this trial mirrors a pattern seen across Parkinson's research, making it harder to detect real treatment effects. The absence of benefit, combined with possible cognitive and sleep harms, challenges popular assumptions about cannabis for Parkinson's.
What This Study Doesn't Tell Us
Only two weeks long, which may be too short to detect meaningful effects. Strong placebo response. Relatively small sample. The authors note that longer, larger trials with better research cannabis products are needed.
Questions This Raises
- ?Would a longer trial with higher THC ratios produce different results?
- ?Are certain Parkinson's symptoms (like pain or anxiety) more responsive to cannabis than motor symptoms?
Trust & Context
- Key Stat:
- No significant motor benefit vs. placebo (p = 0.379)
- Evidence Grade:
- Well-designed double-blind RCT with plasma monitoring, but limited by short duration and strong placebo response.
- Study Age:
- 2024 publication of a two-week trial.
- Original Title:
- Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Parkinson's Disease: A Randomized Trial.
- Published In:
- Movement disorders : official journal of the Movement Disorder Society, 39(5), 863-875 (2024)
- Authors:
- Liu, Ying(4), Bainbridge, Jacquelyn(5), Sillau, Stefan(4), Rajkovic, Sarah, Adkins, Michelle, Domen, Christopher H, Thompson, John A, Seawalt, Tristan, Klawitter, Jost, Sempio, Cristina, Chin, Grace, Forman, Lisa, Fullard, Michelle, Hawkins, Trevor, Seeberger, Lauren, Newman, Heike, Vu, David, Leehey, Maureen Anne
- Database ID:
- RTHC-05487
Evidence Hierarchy
Frequently Asked Questions
Did cannabis help Parkinson's motor symptoms?
Both groups improved, but the difference between CBD/THC and placebo was not statistically significant. The placebo response was strong.
Were there any negative effects?
Sleep, cognition, and activities of daily living scores favored placebo, suggesting the CBD/THC extract may have worsened these areas. Adverse events were generally mild but more common in the treatment group.
What dose was used?
Participants worked up to about 192 mg CBD and 6.4 mg THC daily over two weeks, taken as an oral sesame oil solution.
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Cite This Study
https://rethinkthc.com/research/RTHC-05487APA
Liu, Ying; Bainbridge, Jacquelyn; Sillau, Stefan; Rajkovic, Sarah; Adkins, Michelle; Domen, Christopher H; Thompson, John A; Seawalt, Tristan; Klawitter, Jost; Sempio, Cristina; Chin, Grace; Forman, Lisa; Fullard, Michelle; Hawkins, Trevor; Seeberger, Lauren; Newman, Heike; Vu, David; Leehey, Maureen Anne. (2024). Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Parkinson's Disease: A Randomized Trial.. Movement disorders : official journal of the Movement Disorder Society, 39(5), 863-875. https://doi.org/10.1002/mds.29768
MLA
Liu, Ying, et al. "Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Parkinson's Disease: A Randomized Trial.." Movement disorders : official journal of the Movement Disorder Society, 2024. https://doi.org/10.1002/mds.29768
RethinkTHC
RethinkTHC Research Database. "Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Park..." RTHC-05487. Retrieved from https://rethinkthc.com/research/liu-2024-shortterm-cannabidiol-with-9tetrahydrocannabinol
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.