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 research findings remain scant and inconsistent. This study provides a systematic overview of peer-reviewed 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 (from database inception 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 975 research items, six meta-analyses of clinical and preclinical studies, primarily randomized controlled trials (RCTs), were included. One meta-analysis of five RCTs demonstrated that pure cannabidiol (CBD) or synthetic tetrahydrocannabinol (THC) significantly improved PD symptoms (SMD = −0.41, p = 0.004). Another meta-analysis combining two RCTs and two non-RCTs reported a significant improvement in the Unified Parkinson’s Disease Rating Scale (UPDRS) total score (MD = −4.19, p = 0.03). With regard to pain management, cannabinoids were found effective in one study. Preclinical meta-analyses in animal models showed notable motor improvements, including enhanced rotarod performance (MD = 31.63 s, p = 0.003) and reduced pole test completion times (MD = −1.51 s, p = 0.028). Conclusions. While meta-analyses of clinical studies suggest some benefits of specific cannabinoid formulations, findings are still 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.