Alcohol First, Cannabis Last: Identification of an Especially Risky Use Pattern among Individuals Who Co-Use Alcohol and Cannabis

Abstract

Background: Alcohol and cannabis co-use is common and confers increased risk for potential harms, such as negative consequences and substance dependence. The existing evidence suggests that factors such as dose of delta-9-tetrahydrocannabinol (THC) consumed and order of use of each substance (i.e., using alcohol or cannabis first or last when co-using) may impact co-use outcomes. Existing co-use research has focused primarily on college-samples or young adults, and few studies have explored these nuanced relations among community samples. Methods: We examined survey data from 87 community members (mean age 32.9 years, 49.4% female) recruited from legal market cannabis dispensaries. Using a combination of regression techniques (i.e., OLS, negative binomial, censor-inflated) we modeled relations among co-use ordering patterns, THC dose and cannabis outcomes as well as interactions with sex assigned at birth and age. Results: Individuals who endorsed co-use reported significantly higher CUDIT scores than those who had never co-used (p < 0.01). Using alcohol first and cannabis last (a pattern we refer to as “AFCL”) was more common among females than males (p < 0.01). In the context of typical substance use weeks, more frequently engaging in the AFCL pattern was associated with significantly higher CUDIT scores (p < 0.001) and negatively predicted positive consequences (p < 0.001). Other patterns predicted higher CUDIT scores during heavy use weeks. Conclusions: Results indicate that co-use ordering patterns are related to substance use outcomes. Further research leveraging within-subjects, longitudinal designs is needed to test causal relations between these variables.

Keywords:

• Cannabis
• alcohol
• co-use
• THC
• consequences

Declaration of interest

The authors declare that they have no conflict of interest. The authors alone are responsible for the content and writing of the article.

Availability of data

The data are available from the corresponding author on reasonable request.

Authors’ contributions

HK developed the idea, wrote the introduction and discussion, and co-wrote results and methods. BC ran analyses and co-wrote the methods and results. MP co-wrote the discussion and edited and provided feedback on the entire manuscript. All authors read and approved the final manuscript.

Notes

1 Note that the no co-use group was primarily individuals who only use cannabis (i.e., who did not report using alcohol at all). However, several individuals in the no co-use group reported some drinking during typical and/or heavy weeks (n = 7, mean drinks per drinking day [DPDD] in a typical week =2.28, SD = 2.21; mean DPDD in a heavy week = 2.14, SD = 1.93).

Additional information

Funding

This work was supported by the Colorado Department of Public Health and Environment (CDP HE) grant 2017-3415 to MAP and BT C. HCK is supported by NIH K23AA28238.