Candidates responding to advertisements in local (Ann Arbor, MI, USA) newspapers or flyers posted on bulletin boards around the community were interviewed initially by telephone and asked about health and smoking habits. Candidates who met preliminary criteria were scheduled for an individual interview at the University of Michigan Nicotine Research Laboratory. Cases were recruited first through a parent project of the study—a laboratory investigation [28] involving administration of nicotine to current smokers stratified on nicotine dependence using the Fagerström Test for Nicotine Dependence (FTND) [29] (high dependence: FTND = 4 versus low dependence: FTND < 4) and on depression using the Center for Epidemiological Studies–Depression (CES-D) [30] and a computerized version of the Composite International Diagnostic Interview (CIDI) [31][high depression: CES-D = 16 and/or CIDI life-time diagnosis of major depressive disorder (MDD) versus low depression (CES-D < 16) and no life-time CIDI diagnosis of MDD]. A supplement was awarded later to enable the project to join the National Institute on Drug Addiction (NIDA) Genetics Consortium and to permit recruitment of never-smokers who did not participate in the laboratory study but
