A team of Australian researchers has determined that a medicinal cannabis oil with equal parts THC and CBD can meaningfully reduce the debilitating symptoms experienced by people with Tourette syndrome.
The double-blind trial enrolled 22 adult patients with severe Tourette symptoms, each of whom received both a medicinal cannabis oil and a placebo across two six-week treatment periods.
Participants were given an oral 1:1 THC:CBD formulation, with doses gradually increased over six weeks — starting at 5mg each of THC and CBD per day and rising to 20mg of each — resulting in a significant reduction in both motor and vocal tics.
Researchers also identified a significant link between cannabinoid concentrations in participants' blood and their response to the active treatment.
The authors conclude: “In severe Tourette syndrome, treatment with THC and CBD reduced tics and may reduce impairment due to tics, anxiety, and obsessive-compulsive disorder; although in some participants this was associated with slowed mentation, memory lapses, and poor concentration.”
The study was led by Dr Philip Mosley, a neuropsychiatrist and research fellow at the Wesley Research Institute and QIMR Berghofer Medical Research Institute.
The Lambert Initiative for Cannabinoid Therapeutics and Wesley Research Institute contributed to the study's design and execution, and conducted analysis of participants' blood cannabinoid levels.
Co-author and academic director of the Lambert Initiative Professor Iain McGregor said: “This is such a difficult syndrome to treat. It severely impacts the quality of life of one in 100 young Australians. It is gratifying to know that our result provides strong evidence of an alternative treatment method for these patients in need.
“While there are well-known concerns about the side effects of THC on cognition and mental health, this trial demonstrates that careful dosing with THC in an oral formulation is very well tolerated in a relatively young patient group.”
Dr Mosley added: “This is the first rigorous and methodical trial of medicinal cannabis to be undertaken in a sufficiently large group of people to make definitive conclusions about its effectiveness.
“It shows that medicinal cannabis can reduce tics by a level that makes a life-changing difference for people with Tourette syndrome and their families.”
“In addition, we found that other symptoms associated with Tourette syndrome in our participants also reduced, particularly symptoms of obsessive compulsive disorder and anxiety.”
“Cannabis interacts with specific receptors on nerve cells in the brain that are part of the body’s own endocannabinoid system.
“Effectively, stimulation of these receptors tightens a leaky filter that now stops the involuntary movements and vocalisations from getting out and being expressed by our participants.”
