The Effects of β-myrcene on Simulated Driving and Divided Attention: A Double-Blind, Placebo-Controlled, Crossover Pilot Study.

Background: β-myrcene, one of the most common terpenes found in cannabis, has been associated with sedation. We propose that β-myrcene contributes to driving impairment even in the absence of cannabinoids. Aim: To conduct a double-blind, placebo-controlled crossover pilot study of the effect of β- myrcene on performance on a driving simulator. Method: A small sample (n=10) of participants attended two experimental sessions, one in which they were randomized to receive 15 mg of pure β-myrcene in a capsule versus a canola oil control. Each session, participants completed a baseline block and three follow-up blocks on a STISIM driving simulator. Results: β-myrcene was associated with statistically significant reductions in speed control and increased errors on a divided attention task. Other measures did not approach statistical significance but fit the pattern of results consistent with the hypothesis that β-myrcene impairs simulated driving. Conclusions: This pilot study produced proof-of-principle evidence that the terpene β-myrcene, an agent commonly found in cannabis, can contributes to impairment of driving-related skills. Understanding how compounds other than THC affect driving risk will strengthen the field's understanding of drugged driving.