Demographic, clinical, and ancestry characteristics of the study subjects are displayed in Table 1. The control group was significantly younger than the AD groups and included more females. To determine whether age and gender were confounders for genetic association, we examined associations between age, gender and the seven SNPs across all the cases and controls. There was no significant association found. The diagnostic groups did not differ on the proportion of African ancestry. As expected, Connecticut AD subjects had a significantly higher prevalence of lifetime diagnoses of cocaine and opioid dependence than controls. Lifetime drug dependence diagnoses were not available for the Project MATCH sample. The prevalence of antisocial personality disorder was comparable in the two AD samples and, as expected, was significantly greater than in controls.
