Cannabis Effects on Driving-related Skills of Young Drivers
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.
|Study Design:||Allocation: Randomized
Endpoint Classification: Pharmacokinetics/Dynamics Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Investigator)
Primary Purpose: Basic Science
|Official Title:||Acute and Residual Effects of Cannabis on Young Drivers' Performance of Driving-related Skills|
- Psychomotor impairment (driving) [ Time Frame: Approximate: at baseline (24 hours and 30 minutes before smoking), 30 minutes, 24 hours and 48 hours after smoking, ] [ Designated as safety issue: No ]The driving simulator will objectively measure driving behaviour during a number of pre-programmed driving scenarios designed to test simple reaction time, risk taking, speed, lane deviation, etc. Overall performance measures: Mean Speed, Standard Deviation of Lateral Position, Total Collisions. Zone/ Hazard performance measures: Mean Speed, Standard Deviation of Speed, Standard Deviation of Lateral position, following distance, when passing slow moving vehicle, braking distance from hazard.
- Area under the blood concentration versus time curves for delta-9-tetrahydrocannabinol, carboxy-tetrahydrocannabinol, and 11-hydroxy-tetrahydrocannabinol [ Time Frame: Approximate: 30 minutes pre-dose, 5, 15, 30 minutes and 1, 2, 3, 4, 5, 6, 24 and 48 hours post-dose ] [ Designated as safety issue: No ]
- Vital signs [ Time Frame: Approximate: 30 minutes pre-dose, 5, 15, 30, minutes and 1, 2, 3, 4, 5, 6, 24, and 48 hours post-dose ] [ Designated as safety issue: No ]Blood pressure, pulse, temperature, and respiration rate will be assessed.
- Subjective drug effects [ Time Frame: Approximate: 24 hours, and 30 minutes pre-dose. 5, 15, 30 minutes and 1, 2, 3, 4, 5, 6, 24 and 48 hours post-dose ] [ Designated as safety issue: Yes ]Visual analogue scales will be used to measure subjective pharmacodynamic responses. How participants feel before and after drug administration will be assessed.
- Cognitive testing [ Time Frame: Approximate: 24 hours, and 30 minutes pre-dose, and 1, 24, and 48 hours post-dose ] [ Designated as safety issue: No ]Measures of cognitive ability will be assessed using the Digit Symbol Substitution Test, Hopkins Verbal Learning Test - 2, Continuous Performance Test, and Grooved Pegboard test.
- Urine carboxy-tetrahydrocannabinol to creatinine ratio [ Time Frame: Approximate: 30 minutes pre-dose, and 6, 24, and 48 hours post-dose ] [ Designated as safety issue: No ]Determination of the ratio of excreted THC metabolite carboxy-THC to creatinine (a normal breakdown product of muscle) will determine whether participants have used cannabis between testing days, and hence will be excluded from further participation.
|Study Start Date:||July 2012|
|Estimated Study Completion Date:||July 2015|
|Estimated Primary Completion Date:||May 2015 (Final data collection date for primary outcome measure)|
Active Comparator: Active cannabis
In this condition, participants will receive a cigarette containing 12.5% active THC.
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.
Placebo Comparator: Placebo
In this condition, participants will receive a cannabis cigarette where the active THC has been removed (contains 0% THC).
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).
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.
- 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.
- 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.
- 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.
- 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.
|Contact: Christina Pan, HBSc||416-535-8501 ext firstname.lastname@example.org|
|Contact: Bruna Brands, PhD||416-535-8501 ext email@example.com|
|Centre for Addiction and Mental Health||Recruiting|
|Toronto, Ontario, Canada, M5S 2S1|
|Principal Investigator: Robert Mann, Ph.D.|
|Sub-Investigator: Bruna Brands, Ph.D.|
|Principal Investigator: Bernard Le Foll, M.D., Ph.D.|
|Sub-Investigator: Christine Wickens, Ph.D.|
|Sub-Investigator: Tony George, MD|
|Sub-Investigator: Jürgen Rehm, Ph.D.|
|Sub-Investigator: Beth Sproule, Pharm.D.|
|Sub-Investigator: James Kennedy, MD|
|Principal Investigator:||Robert Mann, Ph.D.||Centre for Addiction and Mental Health|
|Principal Investigator:||Bernard Le Foll, M.D., Ph.D.||Centre for Addiction and Mental Health|