Using data from a community-based study, the Atherosclerosis Risk in Communities study (ARIC(27)), and a University of Wisconsin Transdisciplinary Tobacco Use Research Center (UW-TTURC) smoking cessation clinical trial, we extend the research on the CHRNA5-CHRNA3-CHRNB4 region and smoking cessation success. This research was predicated on hypotheses about the relation among CHRNA5-CHRNA3-CHRNB4 variants, tobacco dependence, and smoking cessation. The two types of studies differ in study duration, amount of experimental contact and monitoring, and type of participants. However, complementary hypothesis were developed for these two types of research designs. In the case of the community trial, the assumption was that dependence would be manifest in cessation occurring at a later age (28-30). In the case of the clinical trial, the assumption was that both heightened genetic risk and dependence would be demonstrated as failed abstinence at end of treatment. Therefore, quitting difficulty was assessed in terms of both relatively long latency to quit in a community sample and failed abstinence at end of treatment in a treatment trial. Analyses addressed three major questions: 1) Does the natural history of smoking cessation
