In a randomized trial, nabiximols treatment for tic disorders did not impair driving fitness, and more patients improved from unfit to fit to drive compared to placebo.
Neurologists treating Tourette syndrome, transportation safety policymakers, patients on medical cannabis concerned about driving.
What the researchers found
Fitness to drive increased from 55.8% to 71.8% in the nabiximols group over 13 weeks, while it decreased from 66.7% to 52.6% in placebo. Only 8.3% of fit nabiximols patients became unfit versus 28.6% in placebo. 42.1% of unfit nabiximols patients improved to fit versus 28.6% in placebo.
Why it matters
The fear that cannabis-based medicines impair driving is a major prescribing barrier. This study shows that for tic disorder patients, nabiximols improved driving-relevant skills by reducing the tics that themselves impair driving.
The numbers in context
64 patients. Nabiximols: fit to drive rose from 55.8% to 71.8%. Placebo: fell from 66.7% to 52.6%. Risk difference: 0.17 favoring nabiximols. 42.1% of initially unfit nabiximols patients became fit.
How the study worked
Substudy of the CANNA-TICS phase IIIb RCT. 64 patients with Tourette syndrome or chronic tic disorders assessed with computerized driving fitness tests at baseline and week 13.
What this study cannot tell us
64 patients at two sites. Computerized test is a proxy for real driving. Tic disorder population may not generalize. 13-week timeframe.
How to read the evidence
Substudy of a well-designed phase IIIb RCT with objective computerized assessment. Small sample at two sites.
When this study was published
2024 publication from the CANNA-TICS trial.
The bigger picture
When a medicine treats a condition that itself impairs driving, the net effect may be positive. Policy restricting all cannabis users from driving may paradoxically make these patients less safe by denying effective treatment.
Questions still open
- Would similar improvements be seen with nabiximols for MS spasticity?
- Should driving fitness testing be part of medical cannabis monitoring?
Common questions
Does medical cannabis impair driving?
Why would a cannabis medicine improve driving?
Read the original research
The Effect of Nabiximols on Driving Ability in Adults with Chronic Tic Disorders: Results of a Substudy Analysis of the Double-Blind, Randomized, Placebo-Controlled CANNA-TICS Trial.
Cannabis and cannabinoid research, 9(5), 1349-1359
Citation
Müller-Vahl, Kirsten R; Pisarenko, Anna; Ringlstetter, Rieke; Cimpianu, Camelia-Lucia; Fremer, Carolin; Weidinger, Elif; Jenz, Eva Beate; Musil, Richard; Brunnauer, Alexander; Großhennig, Anika. (2024). The Effect of Nabiximols on Driving Ability in Adults with Chronic Tic Disorders: Results of a Substudy Analysis of the Double-Blind, Randomized, Placebo-Controlled CANNA-TICS Trial.. Cannabis and cannabinoid research, 9(5), 1349-1359. https://doi.org/10.1089/can.2023.0114