Use and co-use of tobacco and cannabis among couples impacted by alcohol use disorder.

Forkus S.; Hurd J.; Baer M.; Boyd Rogers C.; Noblejas Guloy R.; Hall E.; McCallus R.; Sellers S.; Flanagan J. · The American journal of drug and alcohol abuse · 2026

**Background & Methods** This secondary analysis examined substance co-use patterns among 188 individuals from two dyadic samples: 96 treatment-seeking couples with alcohol use disorder (AUD; N=192) and 46 non-treatment-seeking couples with AUD and intimate partner violence (N=92). The study characterized intrapersonal and interpersonal associations for alcohol, tobacco, and cannabis use within couple dyads. **Key Findings** • Among identified patients with AUD, alcohol-cannabis co-use prevalence ranged from 31.3%-45.7%, alcohol-tobacco co-use from 19.8%-30.4%, and triple co-use from 10.4%-17.4% across both samples. • Treatment-seeking couples demonstrated significant partner correlations in tobacco use (quantity r=.30, frequency r=.45), while non-treatment-seeking couples showed substantially stronger correlations in tobacco quantity (r=.81) and frequency (r=.62), plus cross-substance effects linking one partner's tobacco frequency to the other partner's alcohol frequency (r=.30). • Results provide preliminary evidence for interdependent substance use patterns within couples and suggest tobacco-alcohol cross-effects, indicating partner influences may operate across different substance types rather than within single substances only. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. **Evidence Quality** This study presents significant limitations affecting evidence quality. As a secondary analysis, it was not designed with the current research questions as primary aims. The small sample sizes (96 and 46 couples) limit generalizability, particularly for the non-treatment-seeking subset. The study included predominantly mixed-sex couples (87-97%), potentially limiting applicability to same-sex partnerships. Cross-sectional design precludes causal inference regarding directionality of partner influences. The correlation coefficients, while notable, remain moderate to modest in magnitude. The mechanism underlying observed interdependencies—whether representing shared environmental factors, mutual reinforcement, or selection effects—remains unclear. The study provides exploratory, hypothesis-generating evidence at best (Level 3-4) rather than definitive clinical guidance. Replication with larger, more diverse couple samples and longitudinal designs would strengthen conclusions regarding partner-influenced substance use patterns in AUD populations.

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