The picture is murky: both addictions co-exist (i.e., there are now two addiction issues), but for the overlapping group, combined use may lead to more alcohol

The picture is murky: both addictions co-exist (i.e., there are now two addiction issues), but for the overlapping group, combined use may lead to more alcohol consumption [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8855954/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8855954/]. There's only a moderately positive effect if cannabis use doesn't grow further, and substitutes alcohol abuse.