Effects of Cannabis/Alcohol on Driving Performance and Field Sobriety Tests

The overarching aim of this study is to examine the impact of acute cannabis and alcohol administration on driving performance, as well as identify methods for detecting driving under the influence of these substances. One-hundred twenty-five healthy volunteers will be randomized into one of 5 conditions; those who receive 1) low dose alcohol and placebo cannabis, 2) low dose alcohol and tetrahydrocannabinol (THC), 3) high dose alcohol and placebo cannabis, 4) placebo alcohol and THC, and 5) double placebo. Cannabis inhaled ad libitum and/or ingested alcohol will take place at the beginning of the day followed by the completion of driving simulations, components of the Drug Recognition Expert (DRE) evaluations, and bodily fluid draws (e.g., blood, oral fluid/saliva, breath) over the subsequent 4 hours after ingestion. The purpose of this study is to determine (1) the impact of Δ9-THC on driving performance with and without concurrent alcohol ingestion (2) the duration of driving impairment in terms of hours from initial use, (3) the relationship between performance on the DRE measures and cannabis/alcohol ingestion, and 4) if saliva or expired air can serve as a useful adjunct to the field for blood sampling.