Epidemiological studies suggest that the use of cannabis is associated with an increase in the risk of motor vehicle collisions. It is also known that younger users may be at increased risk for motor vehicle collisions. Further, the frequency with which cannabis is used may be an important variable in determining the effects of cannabis on driving. The purpose of the present study will be to investigate the effects of cannabis on simulated driving in young as compared to middle-aged drivers. Half of the participants will be occasional users of cannabis and half will be frequent users of cannabis.
Epidemiological studies have established that the use of cannabis can increase the risk of a motor vehicle collision. A number of variables can influence the effects of cannabis on driving. For example, frequent users of cannabis have been shown to have different cognitive and physiological responses to cannabis as compared to occasional users. In addition, we know that younger drivers are more likely to be involved in motor vehicle collisions after alcohol use as compared to older users. The contribution of age and experience with cannabis on cannabis-mediated effects on driving have yet to be delineated in laboratory studies. The purpose of the present investigation will be to determine whether cannabis has different effects on driving in young, as compared to middle aged, drivers. Half of each age group will be occasional users of cannabis and the other half will be frequent users. Eligible participants will attend the laboratory for two test sessions; in one session they will smoke a cannabis cigarette and in the other they smoke a placebo cigarette. Participants will drive a driving simulator before and after smoking the cigarette. Blood for measurement of THC and metabolites will also be collected before smoking the cigarette and at a number of times after smoking. Subjective and cognitive tasks will be completed before and after smoking. It is hoped that the findings of this study will help to inform public perception and policy into the potential effects of cannabis on driving.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
128
Centre for Addiction and Mental Health
Toronto, Ontario, Canada
RECRUITINGStandard deviation of lateral position
A measure of 'weaving' when driving the simulator (meters)
Time frame: Before cannabis exposure and 30 minutes and 2 hours after cannabis exposure
Mean speed
A measure of the average speed while driving the simulator (km/hr)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis exposure
Standard deviation of speed
A measure of the variability in speed while driving the simulator (km/hr)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis exposure
Maximum speed
A measure of the greatest speed obtained while driving the simulator (in km/hr)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis exposure
Following distance
A measure of the distance between the car being driven and the car in front (meters)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis exposure
Braking latency
A measure of the time it takes to move the foot from the gas pedal to the brake when a stop sign is encountered (seconds)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis exposure
Number of collisions
The number of collisions while driving the simulator (total number)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis exposure
Blood concentration of delta-9-tetrahydrocannabinol (THC)
A measure of the psychoactive component of cannabis in blood (ng/ml)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis
Blood concentration of carboxy-tetrahydrocannabinol (THC-COOH)
A measure of the inactive metabolite of cannabis in blood (ng/ml)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis
Blood concentration of 11-hydroxy-tetrahydrocannabinol (11-OH-THC)
A measure of the active metabolite of cannabis in blood (ng/ml)
Time frame: Before cannabis exposure and 25 minutes and 2 hours after cannabis
Systolic blood pressure
A vital sign (mmHg)
Time frame: Before cannabis exposure and 5, 15, 25 minutes and 1, 2, 3, 4 and 5 hours after cannabis
Diastolic blood pressure
A vital sign (mmHg)
Time frame: Before cannabis exposure and 5, 15, 25 minutes and 1, 2, 3, 4 and 5 hours after cannabis
Heart rate
A vital sign (beats/minute)
Time frame: Before cannabis exposure and 5, 15, 25 minutes and 1, 2, 3, 4 and 5 hours after cannabis
Visual Analog Scales such as 'I feel this effect', 'I like this drug effect', 'I feel the good effects'
A measure of the subjective effects of cannabis (on a scale of 0 to 100, where is 100 is the strongest level of agreement)
Time frame: Before cannabis exposure and 5, 15, 25 minutes and 1, 2, 3, 4 and 5 hours after cannabis
Trail Making Test
A measure of the cognitive effects of cannabis (performance speed in seconds)
Time frame: Before cannabis exposure and 70 minutes after cannabis
Verbal Free Recall Task
A measure of the cognitive effects of cannabis (number correct)
Time frame: Before cannabis exposure and 70 minutes after cannabis
Grooved Pegboard Test
A measure of the cognitive effects of cannabis (performance speed in milliseconds)
Time frame: Before cannabis exposure and 70 minutes after cannabis
Simple and Choice Reaction Time Tasks
A measure of the cognitive effects of cannabis (milliseconds)
Time frame: Before cannabis exposure and 70 minutes after cannabis
Vienna Risk-Taking Test
A measure of the amount of risk-taking (latency)
Time frame: One hour after cannabis exposure
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