CANNABIS IN PARKINSON DISEASE

Abstract

There is increasing interest amongst patients with Parkinson’s Disease (PD) regarding the potential therapeutic effects of cannabis. The aim of the present review is to 1) report some of the basic mechanisms of action of cannabis, 2) examine the effect of various substances related to the cannabinoid system in PD models, and 3) examine the effectiveness and safety of cannabis in patients with PD, through an assessment of the quality of clinical trials. The effects of endocannabinoids and of the herbal products of cannabis are complex, as they affect a wide variety of brain functions, while the results from studies in PD animal models are in many ways contradictory, even though some effects appear robust, in particular regarding the phenomenon of dyskinesias. We performed a systematic bibliographical review using Medline/ PubMed, Web of Science, CINAHL, και Cochrane. The quality of 14 clinical trials was ascertained through the Cochrane (4 Randomized Clinical Trials (RCT)) and Newcastle-Ottawa (10 non-randomized Clinical trials) scales. The positive effects of cannabis on motor (5 studies) and non-motor symptoms (4 studies) in PD patients that are reported in the non-randomized studies have not been confirmed in the few available RCTs performed to date. Only one earlier RCT in a very small number of patients showed a reduction of Levodopa-Induced dyskinesias (LIDs), while the other three did not show any effect on motor and non motor symptoms. The most common side effects noted were mild somatic (dizziness, nausea, dysgeusia) and psychotic manifestations (confusion, visual hallucinations). There is insufficient evidence for the safety and effectiveness of the use of cannabis in PD clinical practice