Molecular data from Parkinson’s Disease (PD) patients have implicated the endocannabinoid system in the pathogenesis of PD. Compared to control subjects, PD patients show elevated cerebrospinal fluid levels of anandamide and autopsied brains of PD patients show altered CB1 mRNA expression in the basal ganglia (1,2). Large scale clinical trials designed to evaluate the efficacy of medicinal cannabis as a symptomatic treatment for PD are lacking. Anecdotal reports and a few small-scale studies have reported cannabis use to be beneficial for tremor, rigidity, and bradykinesia (3). Many limitations exist in these studies including short trial duration, small sample sizes and modest effect sizes. A number of reviews and small-scale surveys and studies have been published which evaluate the efficacy of medicinal cannabis as a treatment for PD symptoms such as rigidity and dyskinesias (3-6).
An observational study by the Department of Neurology at Rabin Medical Center assessed the clinical effect of medical cannabis on motor and non-motor symptoms of PD (n = 22). Analysis of specific motor symptoms revealed significant improvement after treatment in tremor, rigidity, and bradykinesia. There was also significant improvement of sleep and pain scores (3).
In a survey performed on 339 PD patients, 85 patients reported using cannabis to treat their symptoms (5). Of these, 45.9% (n = 39), described mild or substantial alleviation of their symptoms;
- 6% (n=26) improvement of rest tremor,
- 7% (n=38) reported alleviation of bradykinesia,
- 7% (n = 32) alleviation of muscle rigidity
- 1% (n=12) improvement of L-dopa-induced dyskinesias
- Only 4 patients (4.7%) reported that cannabis worsened their symptoms.
PD has also been listed as one of the disease conditions for which medical marijuana is allowed in Connecticut, Illinois, Massachusetts, New Hampshire, New Mexico, and New York.
Sativex, a THC:CBD buccal spray has undergone extensive studies for the treatment of multiple sclerosis symptoms including spasticity, rigidity and muscle stiffness. In the Zajicek et al study, the rate of relief from muscle stiffness was twice as high among those given cannabis extract compared to those given placebo (7).
Study overview: MUltiple Sclerosis and Extract of Cannabis: results of the MUSEC trial Zajicek et al 2012. (7).
Cohort: MS patients completed cannabis extract (CE) treatment n = 109, MS patients completed placebo treatment n = 115.
Results: Self-reported relief: 29.4% in CE group, 15.7% in placebo group. Self-reported relief from muscle stiffness, muscle spasms, body pain and sleep disturbance was significantly higher in CE group vs placebo at 4, 8 and 12 weeks.
Safety: Treatment was well tolerated. Over 95% of AE’s were mild to moderate. Rates of AE’s were higher in CE group during titration period and decreased over the course of the study.