The mean age was 39 years (SD = 1.9, range=34�C44). The sample was 86% non-Hispanic White, 7% Black, 1% Hispanic/Latino, and 6% of other backgrounds. Some 5% of participants selleck compound completed less than a high school education, 18% completed high school or general education development (GED) test only, 47% completed some postsecondary education, 19% completed college, and 11% completed a graduate degree. The sample included 740 subjects with no siblings in the analytical sample, 164 sibling pairs, 15 sibling trios, 3 sibling quartets, and 1 sibling quintet from a total of 923 families. Procedure Upon completing informed consent and an in-person interview, all participants (N=1,625) were given a set of self-report questionnaires to complete. Some questionnaires were completed in person, but most were returned by mail.

The completion rate for these questionnaires was 73%. We tested for potential differences between completers and noncompleters of the MPQ, using a p value of .01 because of the large number of comparisons. Current smokers (64.4% completion) were less likely to complete the MPQ than were never-smokers (71.2%) and former smokers (73.35), ��2(2, n=1,590)=10.01. Completion rates were significantly lower for men than for women (62.1% vs. 74.6%), ��2(1, N=1,625)=28.93; for non-White participants than for White participants (58.6% vs. 71.6%), ��2(1, n=1,622)=17.99; and for those without a history of major depressive disorder than for those with such a history (67.3% vs. 76.6%), ��2(1, n=1,605)=12.25.

Completion of the MPQ was not significantly associated with education or marital status nor was it associated with lifetime alcohol dependence, substance dependence, or conduct disorder. Measures Smoking status. Smoking histories were obtained by the Lifetime Interview of Smoking Trajectories and the Quitting Methods Questionnaire, developed by the Methods and Measurement core of the TTURC: NEFS. These instruments obtain detailed information on participants�� experiences with tobacco smoking beginning from experimentation, progression to regular smoking, levels of consumption, and patterns of quit attempts. In addition, tobacco dependence according to DSM-IV criteria (American Psychiatric Association, 1994) was assessed using a modified version of the Composite International Diagnostic Interview (CIDI; World Health Organization, 1990).

This module is described in detail in Dierker et al. (2007). Data were available to classify 1,107 participants (98.0% of the sample) according to whether they were never-smokers, former smokers, or current smokers. Never-smokers were defined as those individuals who had never smoked on a weekly or more frequent basis and had smoked fewer than 100 cigarettes in their lifetime. Former smokers were defined as regular smokers (at least weekly) or nonregular smokers who had smoked at least 100 cigarettes who were not currently AV-951 smoking.