The purpose of these analyses is to examine 1) the relationship between nicotine dependence and other psychiatric disorders, 2) the association between these genetic variants and comorbid psychiatric disorders, 3) the potential risk moderation by comorbid psychiatric disorder for nicotine dependence, and 4) the power. First, we examined the distribution of comorbid disorders among cases and control, and then modeled the lifetime associations between nicotine dependence and comorbid disorders in logistic regression models adjusting for age, gender, and education. Because lifetime prevalences of many psychiatric disorders were known to differ between men and women, we compared the associations of nicotine dependence with comorbid disorders across gender. The differences in comorbidity patterns across gender were then tested in logistic regression models.
