Effects of nicotine-alcohol co-use on alcohol-induced blackouts and other alcohol-related consequences in college students

Rationale: Alcohol-induced blackouts (AIBs) are common in college students and are associated with other alcohol-related consequences. Alcohol-nicotine co-use is also common in this population. Nicotine has cognitive-enhancing properties impacting multiple cognitive domains, including those impaired by alcohol (e.g., attention), but it is unclear whether nicotine affects AIB risk or the relationship between AIBs and other alcohol-related consequences. Objectives: We examined the moderating effects of nicotine use on the associations between (a) alcohol and AIBs and (b) AIBs and other consequences (total and serious: sexual, legal, or those with potential to cause great harm). Methods: College students who reported past semester heavy drinking and at least 1 AIB (N = 79, 55.7% female, 86.1% White) wore alcohol sensors and completed daily diaries over four consecutive weekends (89.9% completion). Multilevel models were conducted to test for moderating effects of nicotine (yes/no) on the alcohol-AIB relationship and the AIB-consequence relationship, adjusting for sex, race/ethnicity, and baseline nicotine use. Results: Concurrent alcohol and nicotine use did not moderate the alcohol-AIB relationship, but weakened the associations between AIBs and both (1) total consequences and (2) serious consequences. On days with nicotine use, AIBs were associated with approximately 30% fewer total consequences and 50% fewer serious consequences than days without nicotine use. Conclusions: College students experienced fewer total and serious consequences on AIB nights when nicotine was used compared to AIB nights when nicotine was not used. Future research should explore potential mechanisms underlying the observed effects.