Prospective Associations of Behavioral Economic Demand for Cannabis and Alcohol With Simultaneous Cannabis and Alcohol Use Among Young Adults

Behavioral economic demand for cannabis and alcohol is robustly associated with cannabis use and alcohol use, respectively. However, few studies have examined the contributions of cannabis and alcohol demand to simultaneous cannabis and alcohol use, which is common among young adults. We examined prospective associations of cannabis demand and alcohol demand with propensity for simultaneous use (broadly defined as using both cannabis and alcohol in the same day) and with cannabis and alcohol consumption during simultaneous use days among young adults. Young adults reporting simultaneous use (N = 107) completed a Marijuana Purchase Task assessing cannabis demand and an Alcohol Purchase Task assessing alcohol demand. They then completed daily smartphone surveys over 21 days assessing cannabis and alcohol use. Multilevel models revealed that higher cannabis demand (i.e., higher Omax, Pmax, and intensity; lower elasticity) was uniquely associated with greater propensity for simultaneous use relative to nonuse. In addition, higher alcohol demand (lower elasticity) was uniquely associated with greater propensity for simultaneous use relative to cannabis-only use, and higher cannabis demand (higher break point and intensity, lower elasticity) was uniquely associated with greater propensity for simultaneous use relative to alcohol-only use. Furthermore, in models limited to simultaneous use days, greater cannabis demand (higher Omax, lower elasticity) and lower alcohol demand (higher elasticity) were uniquely associated with greater overall cannabis flower consumption, and higher alcohol demand (higher Omax, lower elasticity) was uniquely associated with greater overall alcohol consumption. Results suggest that individual differences in cannabis and alcohol demand may contribute to simultaneous cannabis and alcohol use behaviors in a substance-specific pattern. Furthermore, cannabis demand may more strongly drive the tendency to engage in simultaneous use (vs. nonuse) relative to alcohol demand.