Simultaneous use of marijuana and alcohol: Potential prevention targets among young adults who use alcohol

Simultaneous alcohol and marijuana use (SAM) such that their effects overlap has emerged as a behavior that is riskier than using either substance separately. It has been associated with high-risk binge drinking and driving while intoxicated during young adulthood, and it has been demonstrated to cause greater physical and mental impairment than use of alcohol or marijuana separately. To identify intervention and prevention targets specific to SAM, we examined the relationships between alcohol- and marijuana-specific beliefs and attitudes (risk factors) and self-reported SAM compared to non-simultaneous co-use (CAM) and alcohol use only in the past 30 days in a sample of young adults (n = 1,023, mean age = 23.17; SD = 0.43). Of those who reported drinking alcohol in the past 30 days, 20.7% reported SAM, 12.6% reported CAM, and 66.6% reported using only alcohol. Results from multinomial logistic regression analyses indicated that some marijuana-specific risk factors (e.g., belief that it is not at all wrong for someone their age to use marijuana) differentiated SAM or CAM from alcohol use only, but alcohol-specific risk factors generally did not. However, the perceptions that parents approved of their using marijuana or frequently drinking heavily were associated with a greater likelihood of SAM compared to CAM (OR ranged from 2.25 to 3.53). Findings point to the salience of individuals' attitudes and beliefs around marijuana use and their perception of parental approval of heavy drinking and marijuana use as potential targets for prevention programs targeting risk reduction among young adults.