A total of 22 adults with severe TS received THC:CBD oil titrated upward over 6 weeks to a daily dose of 20 mg of THC and 20 mg of CBD, followed by a 6-week course of placebo . Only six participants had not previously used cannabis.The mean baseline YGTSS total tic score was 35.7. At 6 weeks, the reduction in total tic score was 8.9 with THC:CBD vs 2.5 with placebo.
On average, the magnitude of the tic reduction was"moderate" and comparable to the effect observed with existing treatments such as antipsychotic agents, the investigators note. The symptomatic response to THC:CBD correlated with serum metabolites of the cannabinoids, further supporting a biological relationship, the researchers note.
"Like many studies of psychoactive compounds, blinding among participants was a problem," the researchers note. Despite best efforts to conceal treatment allocation and match placebo to the active agent in terms of color and smell, most participants were able to correctly guess their treatment order.