Exploring Medical Cannabis and Tourette’s Syndrome

Tourette’s Syndrome (TS), also known as Gilles de la Tourette’s Syndrome, is a neurodevelopmental disorder that is largely characterised by vocal and physical tics. These tics, which can include twitches, humming noises, grunting, or calling out words or phrases, can often cause significant distress and functional impairment to the individual. Dysfunctional neurobiological and psychological processes contribute to the development of tics, though emotional reactions such as anxiety and stress are thought to exacerbate TS symptoms. TS can have a significant impact on an individual’s quality of life, with up to 88% of patients reporting negative effects on their social skills, relationships, and difficulties at school. 

An individual may receive a TS diagnosis if they experience two or more motor tics and at least one vocal tic, occurring multiple times a day, nearly every day, for longer than a year, with onset before the age of 18. In some cases, comorbid disorders may also develop, including obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), and depression and anxiety disorders – all of which may worsen social difficulties and quality of life measures in TS patients. The pathophysiology of TS is still not completely understood, making effective treatment and symptom management difficult. However, evidence suggests that abnormalities in the brain, specifically the GABA and dopaminergic pathways, may play a role. 

As the endocannabinoid system has been found to play a significant role in basal ganglia function through modulation of neurotransmitters – including dopamine and GABA – individuals have sought to research further into medical cannabis and Tourette’s Syndrome.

Medical Cannabis and Tourette’s Syndrome

As dopamine plays an important role in TS, dopamine-blocking drugs are often used to reduce tics. Conventional treatment of TS also includes behavioural interventions and other pharmacological treatments, including nondopaminergic agents and typical and atypical antipsychotics. While these pharmacological interventions can be effective, they are often associated with intolerable adverse effects. As a result, many patients and their clinicians are interested in alternative therapies that may improve symptoms while reducing potential side effects.

However, there remains a paucity of clinical evidence supporting the efficacy of medical cannabis as a treatment for TS. A recent study aimed to describe real-life experiences and assess the long-term effects of patients with TS using medical cannabis.

Design and Methods of the Study

The researchers identified patients for participation using a medical cannabis clinic’s patient registry. Patients received a license for the use of medical cannabis from the Israeli Ministry of Health and were instructed on proper administration by a qualified nurse. Patients were prescribed either an oil solution or cannabis flower for the treatment of TS. Patients under the age of 9 were excluded as vocal tics usually don’t develop until around this age. Patients were divided into two groups (Group A and Group B). Both groups completed a questionnaire both prior to initiating medical cannabis treatment but only Group A also completed a follow-up questionnaire at six months.

The researchers recorded and compared baseline characteristics of patients, in addition to the presence and frequency of vocal and motor tics, quality of life, general mood, employment status, and number of medications of conventional treatment. In Group A, a sub-analysis of the changes seen after the six-month study period was made and adverse events were recorded.

Results of the Study

A total of 70 patients were included in the study, of which 28 patients reported the use of conventional drug therapies for the treatment of TS. The drugs most commonly reported were selective serotonin reuptake inhibitors (SSRIs), atypical antipsychotics, and monoamine depletors. Group A included 57 patients who completed both questionnaires, while Group B included 13 patients who did not complete the follow-up questionnaire. No significant differences were identified between the two groups at baseline.

Of the participants in Group A, 47 patients answered the questionnaire sections on cannabis consumption, product type and daily dose. The average daily dose of THC and CBD were 123 mg and 50.5 mg, respectively. A majority of participants (69%) used high-THC cannabis products. Among patients who reported the use of medications prior to medical cannabis treatment, the average number of medications used was two. After six months of treatment, this fell to an average of 0.5 (0-1). This was a statistically significant reduction. Furthermore, adverse events were considered mild, with the most commonly reported being dizziness (n = 4), increased appetite (n = 3), fatigue (n = 3), and dry mouth (n = 3). 

Of patients who had vocal tics at baseline, the majority (54.2%) reported no change after six months of medical cannabis treatment. Five patients (10.4%) reported an improvement while four (8.3%) reported worsening of vocal tics. Similar results were seen for motor tics with neither symptom demonstrating a clinically significant improvement. Of the participants in Group A (n = 57), 9 reported OCD as a comorbidity; a third of these patients (n = 6) reported an improvement following medical cannabis treatment. 

Information for quality-of-life comparisons before and after 6 months was available for 43 patients: Thirty (69.8%) patients reported an improvement, 11 (25.6%) patients reported no change, and 2 (4.6%) patients reported worsening. These findings demonstrate a statistically significant change.

Conclusions

The data collected from this study may shed light on the impact of medium-term medical cannabis use in TS patients. While the results of this study are promising, the researchers acknowledge some limitations to the study design, including the small sample size, lack of objective measure tic assessments and missing data on conventional medications used or stopped by patients. Finally, it is suggested that future studies be implemented to further evaluate the effectiveness of medical cannabis through large-scale randomised clinical trials to better understand its effectiveness and safety prior to routine use in clinical practice.