Hollis Karoly, PhD
Assistant Professor, Department of Psychology, Colorado State University

Cannabis is the most commonly used drug among people who drink alcohol, yet evidence on the effects of using these substances together is quite limited. Two important factors that might impact the relationship between cannabis and alcohol use are the specific type of cannabis used (i.e., THC/CBD content) as well as the order of use (i.e., using alcohol before cannabis or cannabis before alcohol). Another issue relevant for understanding this relationship is the increasing popularity of cannabis products called “concentrates” which contain very high concentrations of THC. No research has been conducted exploring the effects of these concentrates when combined with alcohol. This study aims to address these issues. We will recruit a community sample of individuals who regularly use alcohol and cannabis to participate in study sessions in our mobile laboratory. The sessions will involve individuals consuming different cannabis concentrate products: (THC-dominant [5mg THC/0mg CBD], CBD-dominant [0mg THC/5mg CBD/], 1:1 THC/CBD [2.5mg THC/2.5mg CBD] and placebo [0mg THC/0mg CBD]) along with a moderate dose of alcohol. Half of the participants will use the alcohol before cannabis, and the other half will use the cannabis before alcohol. We will measure intoxication (e.g., balance performance, self-ratings of intoxication) and biological outcomes (e.g., breath alcohol level, heart rate) every 30 minutes for 4 hours after they use the cannabis and alcohol. We expect to see differences in these outcomes depending upon which cannabis concentrate product was consumed. We expect the greatest intoxication in those who used the THC-dominant concentrate and the least intoxication in the placebo group. We will also measure differences between those who used alcohol before cannabis and those who used cannabis before alcohol.