Safety and Tolerability of Cannabidiol in Parkinson Disease: An Open Label, Dose-Escalation Study

Parkinson disease (PD) is a neurodegenerative disorder very common among the older population. Since standard treatments often only partially relieve symptoms, many patients turn to complementary and alternative medication such as cannabis. However, what are the real risks and benefits of cannabis for Parkinson disease patients? A study investigating the safety and tolerability of a range of doses of cannabidiol (CBD) and its effect on common parkinsonian symptoms conducted by a group of physicians at the University of Colorado School of Medicine provided the first glimpse into this topic.
The study focused on CBD - a non-intoxicating, well-tolerated cannabinoid constituent of the cannabis plant and utilized Epidiolex - a FDA approved medication with plant-derived highly purified CBD. Its data indicated that all participants reported adverse events during a period of approximately 1 month on this medication. These most often included diarrhea, drowsiness, fatigue, weight gain, dizziness, abdominal pain, headache, weight loss, nausea, anorexia, and increased appetite. Adverse events were mostly mild; none serious. Abnormally high liver enzymes also occurred in 38.5% participants on high dose. 
Among participants that completed the study, all exhibited improvement in total and motor scores in the Movement Disorder Society Unified Parkinson Disease Rating Scale. In addition, nighttime sleep and emotional/behavioral dyscontrol scores improved significantly.
Based on these findings, the physicians concluded that CBD, in the form of Epidiolex, may be efficacious in PD, but at a relatively high dose was associated with liver enzyme elevations. However, as an open-label study with a small sample size, this study only offered preliminary insights. Future randomized controlled trials to investigate various forms of cannabis in PD, therefore, are urgently needed.

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read the study here