Alcohol and Cannabis Use and Co-Use in Relation to Problematic Use and Driving Under the Influence Among US Young Adults.

Ndisebuye D.; LoParco C.; Berg C. · Substance use & misuse · 2026

**Background & Methods** This cross-sectional analysis examined 2,953 US young adults (ages 18-34) using 2023 data to assess the relationship between alcohol and cannabis co-use patterns and problematic substance use and driving under the influence (DUI). The study compared three use groups: alcohol-only (33.4%), cannabis-only (17.9%), and alcohol-cannabis co-use (48.8%), analyzing self-reported outcomes while controlling for sociodemographics and state legalization status. **Key Findings** • Alcohol-cannabis co-use was associated with significantly greater problematic alcohol use (B = 0.38) and alcohol DUI risk compared to alcohol-only use (aOR = 1.35, 95%CI = 1.07-1.72), with increased alcohol frequency also elevating both outcomes (B = 0.02 for problematic use; aOR = 1.07 for DUI). • Co-use was associated with problematic cannabis use (B = 0.12), though more frequent cannabis use alone was linked to cannabis DUI (aOR = 1.04, 95%CI = 1.03-1.05), suggesting paradoxical effects depending on use pattern intensity. • Simultaneous alcohol-cannabis use demonstrated consistent elevated risk across all outcomes: problematic alcohol use (B = 0.02), problematic cannabis use (B = 0.03), alcohol DUI (aOR = 1.08), cannabis DUI (aOR = 1.05), and combined alcohol-cannabis DUI (aOR = 1.09), indicating multiplicative risk from concurrent consumption. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. The study focused on problematic use patterns and DUI risk rather than clinical adverse effects. **Evidence Quality** This review has moderate limitations. The cross-sectional design precludes causal inference and directionality assessment. Reliance on self-reported data introduces recall and social desirability bias. State legalization variability may influence reporting accuracy. The high prevalence of co-use (48.8%) suggests this population warrants intervention focus, but generalizability to all US young adults requires consideration of sampling methodology. The study provides important epidemiological evidence regarding co-use risks but represents correlational rather than gold-standard experimental evidence.

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