We must also recognize another limitation. The present findings were obtained from a sample of alcohol-dependent females and may be limited in their generality. We implemented this sampling restriction for several reasons. For example, because the subjects possessed a history of alcohol-dependence, their brain function is hypothetically more vulnerable to the effects of additional insults, including those resulting from smoking and obesity. Accordingly, alcohol-dependent subjects constitute a clinically important, high risk group deserving of our attention. In addition, alcohol-dependent subjects possess more conduct problems and nicotine use than non-alcoholic individuals. Limiting the sample to these subjects therefore improves statistical power for demonstrating associations between conduct problems, associated genotypes, smoking, and obesity. Indeed, it is debatable whether the effects of conduct problems and smoking can be studied with adequate power in adults unaffected by alcoholism or other drug use.
