The use of cannabis with ∆9-tetrahydrocannabinol (THC) content has been shown to have negative effects on vision and driving. The use of other cannabinoids, such as cannabidiol (CBD), which is not attributed with a psychoactive effect, is increasing significantly. This project aims to investigate whether consuming CBD can negatively affect visual function by assessing a wide range of visual parameters and whether these changes may pose a risk for everyday activities such as driving.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
60
Participants are required to vaporize placebo at 0% CBD concentration
Participants are required to vaporize CBD at a concentration of 15%.
Participants are required to vaporize CBD at a concentration of 30%.
University of Granada
Granada, Spain
Change in Overall Driving Performance Score (ODPS) after cannabidiol vaporization
To obtain the ODPS, Z-scores were calculated from individual parameters such as the standard deviation of the lateral lane position or the distance travelled into the opposite lane. The z-score is defined as a measure of how many standard deviations an individual value is below or above the group mean. The average Z-score of the individual driving variables is called the ODPS.
Time frame: Participants are assessed 20 minutes after vaporization
Change in motion detection sensitivity after cannabidiol vaporization
The subject has to indicate the direction of movement of a pattern of moving dots. The percentage of correct answers is obtained for different degrees of coherence.
Time frame: Participants are assessed 20 minutes after vaporization
Change in contrast sensitivity after cannabidiol vaporization
Contrast thresholds are obtained for different spatial frequencies
Time frame: Participants are assessed 20 minutes after vaporization
Change in visual acuity after cannabidiol vaporization
Visual acuity is assessed with a commercial test for distance vision.
Time frame: Participants are assessed 20 minutes after vaporization
Change in fixations after cannabidiol vaporization
The number of fixations made on different stimuli of interest in a task environment is counted using an eye tracker system.
Time frame: Participants are assessed 20 minutes after vaporization
Driving simulator: standard deviation of the lateral lane position (SDLP)
Time frame: Participants are assessed 20 minutes after vaporization
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Distance travelled outside the lane
The SDLP assesses the lane weaving that the subject performs in the lane and indicates whether the vehicle's position is consistent.
Time frame: Participants are assessed 20 minutes after vaporization
Mean speed
Average speed is obtained and analyzed in relation to the speed limits for different sections.
Time frame: Participants are assessed 20 minutes after vaporization
Angular velocity of the steering wheel
The angular velocity of the steering wheel is a metric that indicates the subject's ability to maintain the vehicle's position.
Time frame: Participants are assessed 20 minutes after vaporization