Cannabis Quiets the Tics of Tourette’s Syndrome
Studies show that cannabinoids act on the CB1 receptors in the basal ganglia, cerebellum, and hippocampus, resulting in a dampening of motor and vocal tics.
Tourette’s syndrome is characterized by the presence of multiple motor tics and at least one vocal tic. It is three to four times more prevalent in males than females and standard treatments are mostly ineffective, or are associated with substantial side effects.
Some anecdotal reports point to the efficacy of nabiximols (Sativex®), consisting of THC and CBD in 1:1 ratio, as an alternative treatment strategy. Nabiximols comes in the form of a nasal spray, making administration easy and quick with accelerated onset of relief. Although initially, it was suggested that THC alone might be an effective treatment strategy for patients with Tourette’s syndrome, later reports argued that THC in combination with CBD was required.
Recently, a case report was published describing a young Tourette’s syndrome patient treated with nabiximols. The initial dose was 2.7mg of THC and 2.5mg of CBD per day. This was slowly increased to 24.3 mg THC and 22.5mg CBD. The treatment resulted in significant improvement in overall tic severity and also a 78% improvement in the quality of life.
Additionally, the patient experienced no side effects and tolerated the treatment well. Earlier case studies also reported success in tic reduction by 70% with THC only (10mg/day). To date there are two clinical trials reported, working with the same dose of THC; both are double-blind, placebo controlled and both report significant improvement in tic severity when using cannabinoids.
A significant body of evidence describes how endocannabinoids affect excitatory neurostransmitters in the brain, such as glutamate. These also look at inhibitory neurotransmitters, such as gamma amino butyric acid (GABA) and glycine, also dopamine, serotonin, noradrenaline and acetylcholine. Reduction of tics by cannabinoids is likely conducted by the central CB1 receptor system. In fact, the density of CB1 receptors is highest in the basal ganglia, cerebellum and hippocampus; areas of the brain that are involved in the pathophysiology of Tourette’s syndrome.
Whether cannabinoids regulate the the number of CB1 receptors or the binding to CB1 receptors, or both, is still unclear. One study attempted to answer this question but due to the lack of control subjects, definitive conclusions could not be made. Nevertheless, they concluded that genetic variation in the gene encoding central CR1 is likely not the culprit for Tourette’s syndrome.
So far, the data has shown promising new avenues with cannabinoids in alleviation of tics in treatment-resistant Tourette’s syndrome. Large scale clinical trials are the next logical step in this realm of medical cannabis research. Indeed, the CANNA-TICS trial initiated in March 2017, in Hannover (Germany) represents an exciting new development in this field. The mission of the project is to design new therapeutic strategies with reduced side effects for patients with Tourette’s syndrome and adults with tic disorders.