@article{ref1,
title="Effect of cannabidiol and Δ9-tetrahydrocannabinol on driving performance: a  randomized clinical trial",
journal="JAMA journal of the American Medical Association",
year="2020",
author="Arkell, Thomas R. and Vinckenbosch, Frederick and Kevin, Richard C. and Theunissen, Eef L. and McGregor, Iain S. and Ramaekers, Johannes G.",
volume="324",
number="21",
pages="2177-2186",
abstract="IMPORTANCE: Cannabis use has been associated with increased crash risk, but the  effect of cannabidiol (CBD) on driving is unclear. <br><br>OBJECTIVE: To determine the  driving impairment caused by vaporized cannabis containing Δ9-tetrahydrocannabinol  (THC) and CBD. DESIGN, SETTING, AND PARTICIPANTS: A double-blind,  within-participants, randomized clinical trial was conducted at the Faculty of  Psychology and Neuroscience at Maastricht University in the Netherlands between May  20, 2019, and March 27, 2020. Participants (N = 26) were healthy occasional users of  cannabis. INTERVENTIONS: Participants vaporized THC-dominant, CBD-dominant,  THC/CBD-equivalent, and placebo cannabis. THC and CBD doses were 13.75 mg. Order of  conditions was randomized and balanced. MAIN OUTCOMES AND MEASURES: The primary end  point was standard deviation of lateral position (SDLP; a measure of lane weaving)  during 100 km, on-road driving tests that commenced at 40 minutes and 240 minutes  after cannabis consumption. At a calibrated blood alcohol concentration (BAC) of  0.02%, SDLP was increased relative to placebo by 1.12 cm, and at a calibrated BAC of  0.05%, SDLP was increased relative to placebo by 2.4 cm. <br><br>RESULTS: Among 26  randomized participants (mean [SD] age, 23.2 [2.6] years; 16 women), 22 (85%)  completed all 8 driving tests. At 40 to 100 minutes following consumption, the SDLP  was 18.21 cm with CBD-dominant cannabis, 20.59 cm with THC-dominant cannabis, 21.09  cm with THC/CBD-equivalent cannabis, and 18.28 cm with placebo cannabis. SDLP was  significantly increased by THC-dominant cannabis (+2.33 cm [95% CI, 0.80 to 3.86];  P < .001) and THC/CBD-equivalent cannabis (+2.83 cm [95% CI, 1.28 to 4.39];  P < .001) but not CBD-dominant cannabis (-0.05 cm [95% CI, -1.49 to 1.39]; P > .99),  relative to placebo. At 240 to 300 minutes following consumption, the SDLP was 19.03  cm with CBD-dominant cannabis, 19.88 cm with THC-dominant cannabis, 20.59 cm with  THC/CBD-equivalent cannabis, and 19.37 cm with placebo cannabis. The SDLP did not  differ significantly in the CBD (-0.34 cm [95% CI, -1.77 to 1.10]; P > .99), THC  (0.51 cm [95% CI, -1.01 to 2.02]; P > .99) or THC/CBD (1.22 cm [95% CI, -0.29 to  2.72]; P = .20) conditions, relative to placebo. Out of 188 test drives, 16 (8.5%)  were terminated due to safety concerns. <br><br>CONCLUSIONS AND RELEVANCE: In a crossover  clinical trial that assessed driving performance during on-road driving tests, the  SDLP following vaporized THC-dominant and THC/CBD-equivalent cannabis compared with  placebo was significantly greater at 40 to 100 minutes but not 240 to 300 minutes  after vaporization; there were no significant differences between CBD-dominant  cannabis and placebo. However, the effect size for CBD-dominant cannabis may not  have excluded clinically important impairment, and the doses tested may not  represent common usage.   TRIAL REGISTRATION: EU Clinical Trials Register:  2018-003945-40.    Keywords: Cannabis impaired driving<p /> <p>Language: en</p>",
language="en",
issn="0098-7484",
doi="10.1001/jama.2020.21218",
url="http://dx.doi.org/10.1001/jama.2020.21218"
}