The goal of this study was to conduct a "systematic review regarding the clinical evidence for the efficacy and safety of cannabinoids in treating Parkinson's disease (PD)." It was published in the journal Cannabis and Cannabinoid Research in May 2023.
Included for their review were 13 studies related to cannabis and Parkinson's disease. They found that most side effects were minor with cannabis (with THC) and rare with CBD, except at high doses.
The study is behind a pay wall so details are not available to the general public and we have not reviewed the full paper yet. However, the authors' conclusions were positive:
cannabis, CBD, and nabilone (a synthetic form of THC) were capable of consistently improving motor symptoms more than a placebo.
All treatments improved various non-motor symptoms, particularly with cannabis improving pain intensity, and CBD improving psychiatric symptoms in a dose-dependent manner [effectiveness increased with dosage]
Cannabinoids have been shown to safely offer important potential in treating motor symptoms in PD and some non-motor symptoms.
The article abstract is here at LiebertPub.com.