(0 to 15); 3) YSR externalizing score (0 to 64); 4) YSR social problems score (0 to 22); and 5) member of a high-risk AD family (Yes versus No). Model 2 removed any non-significant predictors from Model 1. Model 3 added the covariates of: 1) sex (Male = 1 versus Female = 0); 2) interview age (14, 15, 16, or 17); and 3) ancestry (EA versus AA) to Model 2 because the previous study (Kuperman et al., 2013) did not examine their effects. Model 4 included all variables in Model 3 plus the number of T alleles (0, 1, or 2) at rs279871 (an additive genetic model for the high-risk T allele). Model 5 also included all variables in Model 3 but changed the genetic predictor from an additive to a recessive genetic model indicator for a homozygous TT genotype (two copies of the T allele versus 0 or 1 copy). Likelihood Ratio Test (LRT) and model fit statistics Akaike information criterion (AIC) and Schwarz Bayesian criterion (SBC) were used to determine the final model. After the final model was determined, exploratory analysis for a possible genetic by environmental (G X E) interaction was performed.
