For EA adolescents, at the bivariate level, P3 amplitude was significantly associated with externalizing behavior scores (r = −0.07). However, in a regression model including age and sex as covariates, the association did not maintain significance (BEA = −0.01, β = −0.06, 95% CI −0.13 to 0.02, ΔR2 = 0.00, 95% CI −0.00 to 0.01; Fig. 1a). At the bivariate level, as well as within the regression model, there were no significant associations between P3 amplitude and externalizing behavior scores for AA adolescents (r = 0.00; BAA = 0.00, β = 0.02, 95% CI −0.07 to 0.10, ΔR2 = 0.00, 95% CI −0.00 to 0.00; Table 2, Fig. 1b). For EA and AA adolescents there were significant main effects of sex such that males endorsed higher levels of externalizing behaviors (βEA = −0.11, 95% CI −0.18 to −0.05; βAA = −0.12, 95% CI −0.21 to −0.03). When tested, there was no evidence of a significant EXT PGS by sex interactions (βEA = −0.02, 95% CI −0.10 to 0.06; βAA = −0.02, 95% CI −0.11 to 0.06; online Supplementary Table 3).
