Cannabis Effects on Driving-related Skills of Young Drivers
Condition: Psychomotor Impairment
MeSH terms: Psychomotor Disorders; Marijuana Abuse
Study type: Interventional

Summary: 
      Motor vehicle collisions are the leading cause of death for young people. The investigators
      have recently found that driving after using cannabis is more common among young Canadian
      drivers than driving after drinking. While this observation raises concerns, the effects of
      cannabis on driving-related skills in this age group are not well understood. As well,
      evidence suggests that residual effects of cannabis on driving-related skills may be observed
      up to 24 hours later. These residual effects may have important implications for the effects
      of cannabis use on collision risk, but little evidence on them in available. This study will
      examine the effects of a single dose of cannabis (marijuana) on driving-related skills
      immediately following consumption, 24 hours later, and 48 hours later. To date, the residual
      effect at 48 hours has not been examined. A total of 142 subjects aged 19 to 25 years old
      will be randomly assigned to smoke either a placebo or active cannabis cigarette (12.5% THC
      potency). Following an eligibility screening and practice session, participants will attend 3
      testing days; drug-administration, 24-hour follow-up and 48-hour follow-up. The effects of
      cannabis/placebo on performance of driving-related skills using a high-fidelity driving
      simulator will be assessed on each testing day. The effects of cannabis on mood, cognition,
      memory and complex reaction time will also be assessed. Identifying factors that affect the
      collision risks experienced by young drivers is a public health priority. While many young
      people believe that cannabis does not impair driving, some recent studies suggest that these
      may be very dangerous beliefs. This study will provide important information on how cannabis
      may affect the driving skills of young drivers, to inform efforts to understand and address
      cannabis-related collision in this age group.
    

Detailed description: 
      This study will test the prediction that residual effects of an acute dose of cannabis on
      driving-related skills will be observed in a group of young drivers 48 hours following a
      single dose of smoked cannabis, and will also examine the effects of an acute dose of
      cannabis on those skills using driving simulator technology.

      Study Objectives

        1. Examine the residual effects of a moderate dose of cannabis (12.5% THC) on driving
           simulator performance of young drivers. Simulated driving performance, tests of
           cognition, verbal memory, and mood will be measured concurrently with levels of
           cannabinoids in biological fluids at approximately 24 and 48 hours following acute drug
           exposure in male and female drivers aged 19 to 25. We will test the hypothesis that
           performance on a high-fidelity driving simulator task will be significantly impaired
           approximately 24 hours following a dose of cannabis in comparison to a placebo
           condition.

        2. Examine the acute effects of a moderate dose of cannabis (12.5% THC) on driving
           simulator performance of young drivers. Simulated driving performance, tests of
           cognition, verbal memory, and mood will be measured concurrently with levels of
           cannabinoids in biological fluids before and after drug administration. Cannabinoid
           levels in biological fluids will be measured over a 6 hour period following drug
           exposure. We will examine the relationship of cannabinoid levels to performance measures
           in this time frame.

        3. Explore the effects of driving history, driving attitudes, and individual difference
           measures (e.g., demographics, drug and alcohol use, etc.) on the acute and residual
           effects of cannabis on driving simulator performance of young drivers. Exploratory
           analyses will be undertaken to determine if the acute and residual effects of cannabis
           on the driving simulator task are influenced by these measures.

        4. Determine if a relationship exists between genetics and THC response. As an ancillary
           aim, blood samples may be collected for future research to determine if a relationship
           exists between genetic polymorphisms and pharmacokinetic and pharmacodynamic responses
           to cannabis.

      Study Design and Duration

      The study is a double-blind, placebo-controlled mixed-design study, including a randomized
      between-subjects comparison of the effects of smoked cannabis and both between- and
      within-subjects examination of its residual effects at 24 and 48 hours following one-time
      drug administration. Although a placebo condition is part of the study, this is not a
      treatment study.

      Initial contact with potential subjects will be made via telephone, and study personnel will
      conduct a telephone screen for eligibility. Upon eligibility confirmation by telephone,
      participants will be asked to attend CAMH for an eligibility assessment. The study will
      consist of 5 sessions for each subject (an eligibility assessment, a practice day, and three
      subsequent testing days). Participants will be asked not to use cannabis for 48 hours prior
      to attending the practice day (Session 2). Although Session 1 can be completed at any time
      prior to the remaining study sessions, Sessions 2 - 5 must be performed on consecutive days.

      In certain instances, the Qualified Investigator may ask a participant to return for
      re-screening, e.g. repeat of urine test or other assessments performed for eligibility
      assessment. Also, in case of unforeseen delays in scheduling study participation, the
      Qualified Investigator will determine if there is a need to ask a participant to repeat some
      assessments, e.g., physical examination.
    

Intervention name(s): delta-9-tetrahydrocannabinol; Placebo
Intervention type(s): Drug; Drug
Intervention description(s): A single cannabis cigarette (potency 12.5% THC) will be given to participants to smoke over a 10 minute period, ad lib. If the cigarette is not smoked in its entirety, the remainder will be weighed to estimate dose.; A single placebo cannabis cigarette (0% THC) will be given to participants to smoke over a 10 minute period, ad lib. If the cigarette is not smoked in its entirety, the remainder will be weighed to estimate dose (as this is a double-blind study).
Other intervention name(s): cannabis sativa; marijuana; cannabis sativa; marijuana
Intervention MeSH terms: Dronabinol
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: cannabis impaired driving; driving simulation; acute psychopharmacologic effects of cannabis; residual effects of cannabis; young drivers