Simultaneous use of alcohol and cannabis is a prevalent behavior among young adults. Numerous studies have demonstrated that individuals who engage in simultaneous use tend to consume higher quantities of both substances and experience more substance-related problems, such as impaired driving, hangovers, blackouts, and social repercussions, compared to those who use alcohol and cannabis separately. However, existing studies have seldom investigated how the combined quantities of alcohol and cannabis impact the occurrence of negative consequences. This study aims to explore the interaction between the quantities of cannabis and alcohol consumed and their influence on predicting negative consequences on days when both substances were used simultaneously.
The study examined 151 young adults aged 19 to 25 in Ontario, Canada, who reported recent simultaneous alcohol and cannabis use. Over 21 days, participants completed daily surveys on their alcohol and cannabis consumption and any resulting negative consequences. The study used multilevel models to assess whether negative consequences differed between simultaneous and single substance use days and how the quantities of alcohol and cannabis interacted to predict negative outcomes on simultaneous use days.
The study found that the simultaneous use of alcohol and cannabis resulted in more negative consequences compared to the independent use of either substance. Increased consumption of cannabis flower moderated the effects of alcohol, resulting in a less pronounced association between alcohol intake and negative outcomes. Additionally, the study indicated that the interaction between alcohol and cannabis concentrates varied by sex. For females, greater use of cannabis concentrates mitigated the negative effects associated with alcohol consumption, whereas for males, increased cannabis concentrate use intensified the negative consequences related to alcohol intake. These findings highlight that the relationship between alcohol and cannabis quantities is complex and can be influenced by factors such as the form of cannabis consumed and the participant’s sex.
Takeaway: Simultaneous use of alcohol and cannabis among young adults leads to more negative consequences, with the impact influenced by the form of cannabis consumed and the individual’s sex, highlighting the need for tailored interventions.