Driving Under the Influence

Co-administration of cannabis and tobacco is a common practice, but there is little experimental evidence aimed at understanding the reasons for this prevalence. Some preliminary evidence suggests that tobacco may actually counteract the cognitive-impairing effects of cannabis, and may also increase the subjective ('liking') effects of cannabis, but results are inconclusive. Further, there are no studies into the effects of tobacco on other cannabis-related harms such as driving, or on the ability of tobacco to alter the blood levels of THC, the chemical responsible for the psychoactive properties of cannabis. The purpose of the present study will be to evaluate the effects of tobacco, cannabis or combinations of tobacco and cannabis on driving, cognition, subjective effects and blood THC. Driving will be assessed using a state-of-the-art driving simulator that allows for the safe and objective measurement of the effects of intoxicating substances on driving. Participants will be regular users of cannabis and will be invited to the lab for four counterbalanced test sessions. In these test sessions they will drive the simulator and undergo cognitive tests before and after smoking: 1) cannabis; 2) tobacco; 3) cannabis + tobacco; or 4) placebo. Outcomes will be measured at several time points after smoking the product. Participants will also give blood for determination of levels of THC, and will complete subjective effects questionnaires both before and after smoking the cigarette. This study will be one of the first experimental laboratory studies of the reasons behind co-administration of tobacco and cannabis.

The goal of this clinical trial is to evaluate whether in-vehicle sensor data can be used to detect cannabis-impaired driving in healthy adult recreational cannabis users. The study aims to assess whether changes in vehicle, driver, and physiological sensor data can distinguish sober driving from cannabis-impaired driving, and how driving performance changes from baseline to approximately 1 to 6 hours after controlled cannabis consumption. Researchers will compare driving behavior and in-vehicle sensor data from participants who receive controlled cannabis administration with data from a randomized reference group without cannabis exposure, to determine whether cannabis-related impairment driving can be identified on the basis of machine learning. Participants will complete screening and baseline assessments and drive an instrumented vehicle on a closed test track under sober conditions. Participants assigned to the experimental arm will receive controlled cannabis administration, while participants in the reference arm will receive no intervention. All participants will perform repeated standardized driving sessions over several hours and complete traffic-medical, traffic-psychological, and in-vehicle pre-driving tests. Biological samples and in-vehicle sensor data will be collected throughout the study.