Cannabis' Impact on Alcohol Consumption

This study employs a repeated measures experimental design to examine the effect of THC-dominant (9.53% THC and 0.09% CBD) dose of cannabis and CBD-dominant (0.35% THC and 11.27% CBD) dose of cannabis, relative to placebo, on subsequent drinking in an alcohol choice task in which participants choose either to drink or receive monetary reinforcement for drinks not consumed. Cannabis will be administered simultaneously with an alcohol-priming dose or alcohol placebo. The study will enroll up to 350 nontreatment-seeking heavy episodic alcohol drinkers who use cannabis weekly to obtain the final sample of 200 with complete data. Participants will be tested at a baseline session, during three experimental sessions, and then during a subsequent 4-week period in the natural environment using a smart-phone application. Findings have important implications for cannabis regulatory science and alcohol use disorder treatment by addressing the relative impact of specific cannabinoids as well as contextual risk in cannabis-alcohol co-use.

Inclusion criteria

• Age 21 to 50
• English-speaking
• cannabis smoking in past two months
• heavy drinking in past two months
• in good physical health and weighing < 250 lbs
• zero breath alcohol at each visit

Exclusion criteria

• positive pregnancy test
• nursing
• positive urine toxicology screen for drugs other than cannabis
• interest to quit or receive treatment for cannabis or alcohol use