Assessment of nicotine and cannabis co-use among adolescents and the association with nicotine and cannabis dependence symptoms.

SIGNIFICANCE: Adolescent nicotine and cannabis co-use is common, but prior studies use imprecise measurement of co-use which may not capture the most problematic behaviors such as same-day use.

METHODS

This cross-sectional study examined patterns of nicotine and cannabis co-use among Southern California high school students in Fall 2022 (N = 3823). Participants were classified into five mutually exclusive past-month nicotine and cannabis use groups: 1) same-day co-use: use of both substances on the same day at least once; 2) past-month co-use: use of both without same-day use; 3) exclusive nicotine use; 4) exclusive cannabis use; 5) no use of either. Adjusted logistic regression models evaluated the association of co-use with any nicotine and/or cannabis dependence symptoms.

RESULTS

Overall, 3.3% reported same-day co-use, 1.5% past-month co-use, 1.6% exclusive nicotine use, 3.1% exclusive cannabis use, and 90.5% no nicotine/cannabis use. Odds of cannabis dependence symptoms (aOR = 4.28, 95%CI[1.98-9.28]) were higher among the same-day vs. past-month co-use group, as were odds of nicotine dependence (aOR = 1.81, 95%CI[0.87-3.77]), though the result was not statistically significant. Compared to past-month co-use, exclusive cannabis use was associated with similar odds of cannabis dependence symptoms (aOR = 0.99, 95%CI[0.47-2.09]), while exclusive nicotine use was associated with non-significant lower odds of nicotine dependence symptoms (aOR = 0.42, 95%CI[0.17-1.04]).

CONCLUSION

Adolescents reporting same-day co-use had significantly greater cannabis dependence symptoms than those reporting past-month but not same-day use of both substances. Using a same-day definition of co-use might capture more problematic co-use behaviors.