Between- and within-group effects of alcohol and cannabis co-use on AUD/CUD in the NSDUH 2002-2019.

Background: Alcohol and cannabis co-use is a between-group risk factor for heavier drinking and negative consequences, but only one study has tested links between co-use and AUD. In addition, few studies focus on risk profiles within co-users, despite heterogeneity in levels of co-use. The current study tested between-group (co-users vs. alcohol-/cannabis-only users) and within-group (patterns of co-use) risk profiles for AUD and CUD in a large, nationally representative sample.
Methods: Data from the 2002-2019 National Study on Drug Use and Health (NSDUH) were used for analyses (N = 1,005,421). Analyses tested 1) whether co-users had greater odds of AUD/CUD than alcohol- and cannabis-only users, respectively, 2) whether there were latent profiles of co-use patterns within co-users, and 3) whether profile membership conferred within-group risk for AUD/CUD.
Results: Co-users were at 3.38 greater odds of having an AUD, but co-use did not confer risk for CUD. Within co-users, five latent profiles emerged: weekly alcohol/cannabis use, weekly alcohol/monthly cannabis, weekly cannabis/occasional alcohol, weekly alcohol/occasional cannabis, and occasional use of both. Multiple comparisons suggested that, generally as frequency of each substance use increased, odds of both AUD and CUD became greater.
Conclusions: Primary alcohol users who also use cannabis are at risk for AUD, but the opposite effect was not observed in primary cannabis users. Higher frequency of each substance also conferred risk within co-users for both AUD and CUD. Findings add novel contributions that should be considered within both alcohol and cannabis use interventions. Future studies using prospective data are needed.
(Copyright © 2021. Published by Elsevier B.V.)