Interplay Between Cigarette and Alcohol Use: Etiological and Treatment Approaches
Background: Previous studies have highlighted a robust bidirectional relationship between alcohol and cigarette use. Co-use of these substances impacts treatment outcomes, as there are no FDA approved medications for the co-use of cigarettes and alcohol. The combination of 2 FDA approved medications for smoking cessation (varenicline) and alcohol use disorder (naltrexone) have shown promise as a treatment option for heavy drinking smokers. Methods: The dissertation project examined both etiology and treatment of the unique subgroup of heavy drinking smokers. Chapter 1 (etiology) utilized a behavioral economics framework in a sample of non-treatment seeking heavy drinking smokers to examine demand for each substance using a hypothetical purchase task in which participants indicate how much of a substance they would consume at varying prices. Chapters 2 and 3 (treatment) consisted of a community sample of treatment-seeking heavy drinking smokers who completed a 12-week randomized clinical trial comparing varenicline plus placebo versus varenicline plus naltrexone for smoking cessation and drinking reduction. Chapter 2 examined the impact of sex hormones in response to pharmacotherapy for female heavy drinking smokers. Chapter 3 examined whether drinking outcomes mediated the relationship between pharmacotherapy and smoking outcomes. Results: Results from Chapter 1 (etiology) revealed cross-substance relationships, with use of one substance predicting greater demand of the opposite substance. Notably, we found a stronger effect of nicotine use on demand for alcohol than vice versa. Results from Chapter 2 (treatment) showed no interaction of sex hormones and pharmacotherapy on smoking outcomes. However, greater ratio of progesterone to estradiol was associated with greater percent days abstinent from alcohol for females assigned to the varenicline plus naltrexone condition. Results from Chapter 3 (treatment) indicated that drinking outcomes did not mediate the relationship between pharmacotherapy and smoking outcomes. However, throughout the active medication phase and follow-up phase there was a significant relationship between drinking and smoking outcomes. Conclusion: These studies use a translational framework combining pharmacology, experimental psychology, and biomarkers of sex differences to address clinical implications of the co-use of cigarettes and alcohol. These studies advance a precision medicine approach whereby the complementarity between smoking and drinking can be clinically targeted.