Combined and Separate Effects of Cannabis and Tobacco: Psychomotor, Subjective and Physiological Outcomes
Status:
Not yet recruiting
Trial end date:
2027-03-01
Target enrollment:
Participant gender:
Summary
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.