Cannabis for Parkinson's Disease: Trial Shows No Benefit, Possible Harm
What Researchers Found About Parkinsons Disease and Cannabis
The Study at a Glance
Published
Movement Disorders, 2024
Researchers
Multiple institutions (USA)
Study Type
Randomized Controlled TrialParticipants
61 patients · 2 weeks
Key Finding
There was no benefit, perhaps worsened cognition and sleep, and there were many mild adverse events. The brief duration and strong placebo response limits interpretation of effects.
Key Finding: There was no benefit, perhaps worsened cognition and sleep, and there were many mild adverse events. The brief duration and strong placebo response limits interpretation of effects.
What Researchers Studied About Parkinsons Disease and Cannabis
Cannabis use is frequent in Parkinson's disease (PD), despite inadequate evidence of benefits and risks.
This was a randomized trial to study short-term efficacy and tolerability of high CBD/low THC cannabis extract.
Participants had PD with motor scores of at least 20 on the MDS-UPDRS (Movement Disorder Society Unified Parkinson's Disease Rating Scale) and tested negative for cannabis.
How This Randomized Controlled Trial Was Conducted
Participants were randomized to CBD/THC (n=31) or placebo (n=30).
They received cannabis extract (from NIDA) as oral sesame oil solution for 2 weeks, increasing to a final dose of 2.5 mg/kg/day.
Mean final dose was 191.8 mg CBD and 6.4 mg THC daily.
The primary outcome was change in motor MDS-UPDRS from baseline to final dose.
Parkinsons Disease Treatment Results
The Main Results:
- 1CBD/THC group: Motor score improved by 4.57 points (P = 0.013)
- 2Placebo group: Motor score improved by 2.77 points (P = 0.014)
- 3Difference between groups: NOT SIGNIFICANT (-1.80, P = 0.379)
- 4Several assessments showed a STRONG PLACEBO RESPONSE
- 5Sleep, cognition, and daily activities: Treatment effect FAVORED PLACEBO
- 6More mild adverse events in CBD/THC group than placebo
- 7CBD plasma level at final dose: 54.0 ng/mL; THC: 1.06 ng/mL
By the Numbers
| Statistic | What It Means |
|---|---|
| 61 patients | Parkinson's disease patients randomized (31 CBD/THC, 30 placebo) |
| P = 0.379 | Non-significant difference between cannabis and placebo for motor symptoms |
| 191.8 mg | Mean final daily CBD dose (with 6.4 mg THC) |
| Worse | Sleep and cognition outcomes actually favored placebo over cannabis |
Parkinson's disease patients randomized (31 CBD/THC, 30 placebo)
Non-significant difference between cannabis and placebo for motor symptoms
Mean final daily CBD dose (with 6.4 mg THC)
Sleep and cognition outcomes actually favored placebo over cannabis
What This Means for Parkinsons Disease Patients
If you have Parkinson's disease and are considering cannabis, this trial provides important cautionary evidence.
While both groups showed motor improvement, there was no significant difference between cannabis and placebo (P = 0.379). The placebo group improved nearly as much as the cannabis group.
More concerning, sleep, cognition, and activities of daily living actually showed worse outcomes with cannabis than with placebo. Mild adverse events were also more common with cannabis.
The researchers concluded there was "no benefit, perhaps worsened cognition and sleep."
This does not mean cannabis never helps anyone with Parkinson's, but this rigorous trial found no evidence of benefit and some evidence of harm. If you use cannabis for PD, discuss these findings with your neurologist.
Quick Answers: Parkinsons Disease and Cannabis
Direct answers based on the findings of this study:
Research Summary: Answers are based on published peer-reviewed studies and represent research findings, not medical recommendations. Individual results may vary. Always consult a healthcare provider before making treatment decisions.
Does marijuana help Parkinson's tremors?
No significant benefit found (P = 0.379). A 2024 RCT of 61 patients found both cannabis and placebo groups improved similarly due to a strong placebo effect. Sleep and cognition were actually worse with cannabis.
Source: Liu et al., Movement Disorders, 2024 (PMID: 38487964)
Is CBD safe for people with Parkinson's?
More side effects and worse outcomes in some areas. Sleep, cognition, and daily activities were WORSE with cannabis than placebo. The researchers found "no benefit, perhaps worsened cognition and sleep."
Source: Liu et al., Movement Disorders, 2024 (PMID: 38487964)
What does research say about cannabis for Parkinson's?
No significant difference from placebo (P = 0.379). A rigorous 2024 RCT found a strong placebo response with both groups improving. Sleep and cognition outcomes actually favored placebo, suggesting potential harm.
Source: Liu et al., Movement Disorders, 2024 (PMID: 38487964)
This is educational content, not medical advice
The research summarized here is for informational purposes only. Individual results may vary, and what works in studies may not work the same way for everyone. Always consult with a qualified healthcare provider before making changes to your treatment plan or starting medical cannabis therapy.
Important Limitations
This study has some caveats to keep in mind when interpreting the results:
- Brief duration (2 weeks only)
- Strong placebo response may have masked any real effect
- Small sample size (61 patients)
- Single dose/formulation tested
- Longer trials with different formulations needed
The Bottom Line on Cannabis for Parkinsons Disease
This RCT of 61 Parkinson's patients found NO significant benefit from high-CBD/low-THC cannabis (P = 0.379). Both groups improved similarly, with a strong placebo response. Concerning findings: sleep, cognition, and daily activities were actually WORSE with cannabis than placebo. Mild adverse events were more common with cannabis. This suggests cannabis may not help, and could potentially harm, people with Parkinson's disease.
Do You Qualify for Medical Marijuana?
If you're living with Parkinsons Disease, you may qualify for a medical marijuana card. Our licensed physicians can evaluate you from home via telehealth.
Related Research & Resources
Related Research
Condition Research
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This condition qualifies for medical marijuana in:
Source
Liu Y, Bainbridge J, Sillau S, et al. "Short-Term Cannabidiol with delta-9-Tetrahydrocannabinol in Parkinson's Disease: A Randomized Trial" Movement Disorders. 2024. DOI: 10.1002/mds.29768
Important Information
Not Medical Advice: This research summary is for educational purposes only. It should not be used to diagnose, treat, cure, or prevent any disease or medical condition. Always consult a qualified healthcare provider before starting or changing any treatment.
Individual Variation: Research findings represent group averages. Your individual response to cannabis may differ based on genetics, other medications, underlying conditions, and many other factors.
Last reviewed: January 25, 2026
Important Notices
Research Summary Disclaimer
This content represents our interpretation of published scientific research for educational purposes. It should not be used to make treatment decisions without consulting a qualified healthcare provider. Individual results may vary from study findings.
FDA Notice
These statements have not been evaluated by the FDA. Cannabis is not intended to diagnose, treat, cure, or prevent any disease. The FDA has not approved cannabis for any medical condition except specific prescription medications.
Copyright & Fair Use
Research summaries are provided under fair use (17 U.S.C. § 107) for educational purposes. We provide brief summaries with attribution, not full reproductions. All studies remain the intellectual property of their respective authors and publishers.
Data Sources
Study information sourced from PubMed®, U.S. National Library of Medicine. Inclusion does not imply endorsement by NLM, NIH, or the federal government.
For complete information, see our Terms of Use and Research Content Policy.
FAQs: Cannabis for Parkinsons Disease
Does cannabis help Parkinson's disease?
No benefit found (P = 0.379). This RCT of 61 patients found both cannabis and placebo groups improved similarly. Sleep, cognition, and daily activities were actually worse with cannabis. Researchers concluded "no benefit, perhaps worsened cognition and sleep."
Is cannabis safe for Parkinson's patients?
More side effects than placebo, with concerns. Sleep and cognition outcomes favored placebo over cannabis. While cannabis was not dangerous, it may not be beneficial and could worsen some symptoms.
Why do Parkinson's patients use cannabis if it doesn't help?
Strong placebo response observed. Cannabis use is frequent in PD "despite inadequate evidence of benefits and risks." Both groups improved similarly, suggesting subjective improvement may not reflect objective benefit.