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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Placebo (CBD 0%) | Placebo Comparator | Participants are required to vaporize a placebo at 0% CBD concentration |
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| CBD 15% | Experimental | Participants are required to vaporize CBD at a concentration of 15%. |
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| CBD 30% | Experimental | Participants are required to vaporize CBD at a concentration of 30%. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Placebo (CBD 0%) | Other | Participants are required to vaporize placebo at 0% CBD concentration |
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| Measure | Description | Time Frame |
|---|---|---|
| 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. | 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. | Participants are assessed 20 minutes after vaporization |
| Change in contrast sensitivity after cannabidiol vaporization | Contrast thresholds are obtained for different spatial frequencies | 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. | 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. | Participants are assessed 20 minutes after vaporization |
| Measure | Description | Time Frame |
|---|---|---|
| Driving simulator: standard deviation of the lateral lane position (SDLP) | Participants are assessed 20 minutes after vaporization | |
| 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. |
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Inclusion Criteria:
Exclusion criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Granada | Granada | 18071 | Spain |
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| ID | Term |
|---|---|
| D002189 | Marijuana Abuse |
| ID | Term |
|---|---|
| D019966 | Substance-Related Disorders |
| D064419 | Chemically-Induced Disorders |
| D001523 | Mental Disorders |
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| CBD 15% | Other | Participants are required to vaporize CBD at a concentration of 15%. |
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| CBD 30% | Other | Participants are required to vaporize CBD at a concentration of 30%. |
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| Participants are assessed 20 minutes after vaporization |
| Mean speed | Average speed is obtained and analyzed in relation to the speed limits for different sections. | 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. | Participants are assessed 20 minutes after vaporization |