Cannabis Use
Conditions
Keywords
cannabis, cannabidiol, vision, driving performance
Brief summary
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.
Interventions
OTHERPlacebo (CBD 0%)
Participants are required to vaporize placebo at 0% CBD concentration
OTHERCBD 15%
Participants are required to vaporize CBD at a concentration of 15%.
OTHERCBD 30%
Participants are required to vaporize CBD at a concentration of 30%.
Sponsors
Universidad de Granada
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 43 Years
Healthy volunteers
Yes
Inclusion criteria
* Being an occasional cannabis and/or cannabidiol user * Have a current driving licence * Have at least one year's driving experience * Drive at least once a week * Monocular visual acuity of at least 6/6 (Snellen) with habitual correction for driving * Absence of binocular disorders
Exclusion criteria
* Certain past or present medical conditions * Current cannabis or alcohol use disorder * Use of other drugs * Pregnancy or lactation * Simulator sickness.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in fixations after cannabidiol vaporization | Participants are assessed 20 minutes after vaporization | The number of fixations made on different stimuli of interest in a task environment is counted using an eye tracker system. |
| Change in Overall Driving Performance Score (ODPS) after cannabidiol vaporization | Participants are assessed 20 minutes after 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. |
| Change in motion detection sensitivity after cannabidiol vaporization | Participants are assessed 20 minutes after 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. |
| Change in contrast sensitivity after cannabidiol vaporization | Participants are assessed 20 minutes after vaporization | Contrast thresholds are obtained for different spatial frequencies |
| Change in visual acuity after cannabidiol vaporization | Participants are assessed 20 minutes after vaporization | Visual acuity is assessed with a commercial test for distance vision. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Distance travelled outside the lane | Participants are assessed 20 minutes after vaporization | The SDLP assesses the lane weaving that the subject performs in the lane and indicates whether the vehicle's position is consistent. |
| Mean speed | Participants are assessed 20 minutes after vaporization | Average speed is obtained and analyzed in relation to the speed limits for different sections. |
| Angular velocity of the steering wheel | Participants are assessed 20 minutes after vaporization | The angular velocity of the steering wheel is a metric that indicates the subject's ability to maintain the vehicle's position. |
| Driving simulator: standard deviation of the lateral lane position (SDLP) | Participants are assessed 20 minutes after vaporization | — |
Countries
Spain
Outcome results
None listed