AAB was measured using a count of the number of ASPD criteria endorsed under criterion A from the DSM-IV.1 In view of our modest sample size, we chose to use a more powerful dimensional phenotype rather than a less powerful diagnostic phenotype. The seven criteria included: engaging in illegal activities; deceitfulness; impulsivity and failing to plan ahead; irritability and aggressiveness; disregard for the safety of self and others; consistent irresponsibility at work or with finances; and lack of remorse. Criterion counts were obtained from items in the reliable (with a kappa=0.70 for ASPD diagnoses) and valid Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA).21, 22 We note that 203 (15%) of participants were administered an early version of the SSAGA that included a skip pattern whereby participants were asked the ASPD questions only if they had endorsed two or more alcohol dependence/abuse, marijuana dependence/abuse or other drug dependence/abuse symptoms. In total, 42 participants (representing 3% of the overall sample) were not asked the ASPD questions because of the skip pattern.
