The Effects of Therapeutic Cannabis and Cannabinoids in Parkinson’s Disease: An Overview of Meta-Analyses

Background: Cannabis and cannabinoids have been investigated for their potential therapeutic effects in Parkinson’s disease, but clinical findings remain scant and inconsistent. This study provides a systematic overview of meta-analyses assessing their impact on health outcomes in patients with Parkinson’s disease.

Methods: A comprehensive search of PubMed, EMBASE, Web of Science, and Google Scholar (up to April 2025) identified meta-analyses evaluating cannabis-based interventions in Parkinson’s disease. Eligible studies reported pooled estimates of effects on neurological symptoms. The most significant findings from the included studies were summarized and qualitatively analyzed.

Results: After screening a total of 975 research items, seven meta-analyses of clinical and laboratory studies, primarily randomized controlled trials (RCTs), were identified. One analysis of five RCTs demonstrated that pure CBD or synthetic THC significantly improved disease symptoms (SMD=−0.41, p=0.004). In contrast, a meta-analysis of three RCTs evaluating various cannabis extracts found no significant effect on the Unified Parkinson Disease Rating Scale (UPDRS) total score (SMD=−0.18, p=0.48). However, another analysis combining two RCTs and two non-RCTs reported a significant improvement in the UPDRS total score (MD=−4.19, p=0.03). With regard to pain management in Parkinson’s disease, a study confirmed that cannabinoids are an effective treatment option. Additionally, a meta-analysis of preclinical studies in animal models indicated notable enhancements in motor function, with improved rotarod performance (MD=31.63 s, p=0.003) and reduced pole test times (MD=−1.51 s, p=0.028).

Conclusions: While meta-analyses of clinical studies suggest some benefits of specific cannabinoid formulations, findings are uncertain. Preclinical data, however, demonstrate interesting motor improvements. Further well-designed RCTs are warranted to clarify the therapeutic role of cannabis in Parkinson’s disease management.