The prevalence of alcohol and drug use disorders is elevated among individuals with nicotine dependence (John, Meyer, Rumpf, & Hapke, 2004). In this sample, for instance, 62% of individuals who reported any lifetime alcohol use disorder also reported lifetime nicotine dependence, compared to 24% of individuals without a lifetime alcohol use disorder history. Comorbidity among alcohol and other drug use disorders was also high. Because it was possible that a comorbid substance use disorder could moderate the relationships between BMI and gender and each substance use disorder of interest, we controlled for any lifetime or past-year drug use disorder and lifetime and past-year nicotine dependence when examining effects on alcohol use disorders in our main analyses. We also controlled for any lifetime or past-year alcohol use disorder and lifetime and past-year nicotine dependence when examining effects on drug use disorders. Finally, when examining effects on nicotine dependence, we controlled for any lifetime and past-year alcohol use disorder and any lifetime and past-year drug use disorder. However, in order to clarify the effect of comorbid substance use disorders, we also present results from analyses that did not include other substance use disorders as covariates.
