In an open-label study, high-dose CBD (Epidiolex) improved motor symptoms by 25% in Parkinson disease patients but caused elevated liver enzymes in 38.5% at the highest doses.
Movement disorder specialists, Parkinson disease patients considering CBD, and neurologists.
24.7% motor improvement, but liver enzymes elevated in 38.5%
What the researchers found
Thirteen Parkinson disease patients taking CBD at 20-25 mg/kg/day showed significant improvement in total MDS-UPDRS scores (17.8% decrease, p=0.012) and motor scores (24.7% decrease, p=0.004). Sleep and emotional/behavioral control also improved. However, elevated liver enzymes occurred in 38.5% at the highest dose, and 23% dropped out due to intolerance.
Why it matters
Cannabis use is increasingly common among Parkinson patients, but controlled data are scarce. This study provides the first dose-escalation safety and tolerability data for pharmaceutical CBD in this population.
The numbers in context
13 participants (10 male); mean age 68.15; motor scores improved 24.7% (p=0.004); liver enzyme elevations in 38.5%; 3 dropouts (23%); common AEs: diarrhea (85%), somnolence (69%), fatigue (62%).
How the study worked
Open-label, dose-escalation study of 13 Parkinson disease patients titrated from 5 to 20-25 mg/kg/day pharmaceutical CBD (Epidiolex) maintained for 10-15 days.
What this study cannot tell us
Open-label design (no placebo control); very small sample; short treatment period (10-15 days); strong placebo effect known in PD trials; high dropout rate; liver enzyme concerns at therapeutic doses.
How to read the evidence
Preliminary: very small open-label study with no placebo control; Parkinson disease has notably strong placebo effects.
When this study was published
Published 2020.
The bigger picture
The motor improvement is promising but must be interpreted cautiously given the open-label design and placebo effect, which is notably strong in Parkinson disease. The liver enzyme concern suggests that the doses used in epilepsy (20-25 mg/kg/day) may be too high for this older population.
Questions still open
- Would lower CBD doses maintain motor benefits while avoiding liver issues? Will placebo-controlled trials confirm these improvements?
Common questions
Does CBD help Parkinson disease symptoms?
Is CBD safe for Parkinson patients?
Read the original research
Safety and Tolerability of Cannabidiol in Parkinson Disease: An Open Label, Dose-Escalation Study.
Cannabis and cannabinoid research, 5(4), 326-336
Citation
Leehey, Maureen A; Liu, Ying; Hart, Felecia; Epstein, Christen; Cook, Mary; Sillau, Stefan; Klawitter, Jost; Newman, Heike; Sempio, Cristina; Forman, Lisa; Seeberger, Lauren; Klepitskaya, Olga; Baud, Zachrey; Bainbridge, Jacquelyn. (2020). Safety and Tolerability of Cannabidiol in Parkinson Disease: An Open Label, Dose-Escalation Study.. Cannabis and cannabinoid research, 5(4), 326-336. https://doi.org/10.1089/can.2019.0068
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