Clinical Trial: Cannabis Effects on Driving-related Skills of Young Drivers
Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title: Acute and Residual Effects of Cannabis on Young Drivers' Performance of Driving-related Skills
Brief 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 Summary:
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
- 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
Sponsor: Centre for Addiction and Mental Health
Current Primary Outcome: Psychomotor impairment (driving) [ Time Frame: Approximate: at baseline (24 hours and 30 minutes before smoking), 30 minutes, 24 hours and 48 hours after smoking, ]
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.
Original Primary Outcome: Psychomotor impairment (driving) [ Time Frame: at baseline (24 hours and 30 minutes) before smoking, 30 minutes, 24 hours and 48 hours after smoking, ]
The driving simulator will objectively measure driving behaviour during a number of pre-programmed driving scenarios designed to test simple and complex reaction time, risk taking, speed, lane deviation, etc.
Current Secondary Outcome:
- 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 ]
- 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 ]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 ]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 ]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 ]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.
Original Secondary Outcome:
- Area under the blood concentration versus time curves for delta-9-tetrahydrocannabinol, carboxy-tetrahydrocannabinol, and 11-hydroxy-tetrahydrocannabinol [ Time Frame: 24 hours and 30 minutes pre-dose. 5, 10, 15, 30 minutes and 1, 2, 3, 4, 5, 6, 24 and 48 hours post-dose ]
- Vital signs [ Time Frame: 24 hours and 30 minutes pre-dose. 5, 10, 15, 30, minutes and 1, 2, 3, 4, 5, 6, 24, and 48 hours post-dose ]Blood pressure, pulse, temperature, and respiration rate will be assessed.
- Subjective drug effects [ Time Frame: 24 hours and 30 minutes pre-dose. 5, 10, 15, 30 minutes and 1, 2, 3, 4, 5, 6, 24 and 48 hours post-dose ]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: 24 hours and 30 minutes pre-dose, and 1, 24, and 48 hours post-dose ]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 ration [ Time Frame: 30 minutes pre-dose, 6, 24, and 48 hours post dose. ]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.
Information By: Centre for Addiction and Mental Health
Dates:
Date Received: May 3, 2012
Date Started: July 2012
Date Completion:
Last Updated: September 21, 2016
Last Verified: September 2016
