Research study · Movement Disorders · 2024
Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Parkinson’s Disease: A Randomized Trial
Verified on PubMed Randomized controlled trial
A 2024 randomized controlled trial in Movement Disorders tested cannabidiol in Parkinson's disease. Motor scores improved in both groups, and the difference between them was not significant. Parkinson's is one of the conditions people ask about most, and this trial did not find the benefit many hope for.
In plain language
Study overview
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.
Findings
Motor scores improved in both groups, and the difference between them was not significant. Sleep, thinking and daily activities slightly favoured placebo, and mild side effects were more common on the extract.
The deeper readScientific analysis
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.
The paper
Citation
Liu Y, Bainbridge J, Sillau S, Rajkovic S, Adkins M, Domen CH, et al. Short-Term Cannabidiol with Δ-9-Tetrahydrocannabinol in Parkinson’s Disease: A Randomized Trial. Movement Disorders (2024). PubMed 38487964 · DOI
Read the abstract as published
BACKGROUND: Cannabis use is frequent in Parkinson's disease (PD), despite inadequate evidence of benefits and risks.
OBJECTIVE: The aim is to study short-term efficacy and tolerability of relatively high cannabidiol (CBD)/low Δ-9-tetrahydrocannabinol (THC) to provide preliminary data for a longer trial.
METHODS: Persons with PD with ≥20 on motor Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) who had negative cannabis testing took cannabis extract (National Institute of Drug Abuse) oral sesame oil solution for 2 weeks, increasing to final dose of 2.5 mg/kg/day. Primary outcome was change in motor MDS-UPDRS from baseline to final dose.
RESULTS: Participants were randomized to CBD/THC (n = 31) or placebo (n = 30). Mean final dose (CBD/THC group) was 191.8 ± 48.9 mg CBD and 6.4 ± 1.6 mg THC daily. Motor MDS-UPDRS was reduced by 4.57 (95% CI, -8.11 to -1.03; P = 0.013) in CBD/THC group, and 2.77 (-4.92 to -0.61; P = 0.014) in placebo; the difference between groups was non-significant: -1.80 (-5.88 to 2.27; P = 0.379). Several assessments had a strong placebo response. Sleep, cognition, and activities of daily living showed a treatment effect, favoring placebo. Overall adverse events were mild and reported more in CBD/THC than placebo group. On 2.5 mg/kg/day CBD plasma level was 54.0 ± 33.8 ng/mL; THC 1.06 ± 0.91 ng/mL.
CONCLUSIONS: The brief duration and strong placebo response limits interpretation of effects, but there was no benefit, perhaps worsened cognition and sleep, and there was many mild adverse events. Longer duration high quality trials that monitor cannabinoid concentrations are essential and would require improved availability of research cannabinoid products in the United States. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Abstract text as indexed by PubMed for this identifier.
In practice
Why this matters
Parkinson's is one of the conditions people ask about most, and this trial did not find the benefit many hope for. Two weeks is short, so it settles less than it seems - but it is the evidence we have.
Browse related research
Condition: Parkinson's disease Topic: CBD Topic: THC
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Reviewed by Dr. Caplan on September 17, 2026.
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