In the first paper, Luczak et al. 3 were able to identify relatively few studies that examine the interrelationships of addictive behaviors among U.S. racial/ethnic groups, and those studies primarily focused on the comorbidity of substance use disorders (alcohol, nicotine, and illicit drugs) and gambling. They report gaps in the literature for the repetitive addictive behaviors of eating/food, internet, sex, love, exercise, work, and shopping. Based on available studies, there is evidence for race/ethnic group differences in rates of substance use and prevalence of addictions. For example, American Indians are consistently higher and Asians consistently lower on rates of alcohol, nicotine, and drug use disorders. African Americans, Latinos, and Whites fall in between, but at changing rank orders, depending on the addictive behavior, timeframe (lifetime or current) assessed, and the inclusion of covariates. There is also evidence that U.S. racial/ethnic groups vary in the co-occurrence and comorbidity of these addictive behaviors. However, the temporal order of onset of these comorbidities is not clear, which is important for understanding whether addictive behaviors represent different or similar underlying mechanisms. The authors note
