To our knowledge, only one recent study has examined associations between brain-based variables and PGS for alcohol use, cannabis use, smoking, schizophrenia, and educational attainment. This study found significant associations between brain-based variables and PGS for specific behaviors (e.g. regular smoking) through using a principal component analyses of multivariate EEG indicators (including P3 amplitude) instead of examining individual EEG indicators (Harper et al., 2021). In contrast, the current study focused specifically on externalizing behaviors as a phenotype of interest. Research on the genetic architecture of externalizing by Karlsson Linnér et al. (2021) as well as the longstanding literature linking the P3 amplitude from a visual oddball task to a broad phenotypic externalizing factor (Gilmore et al., 2010; Patrick et al., 2006) suggests that both the EXT PGS and P3 amplitude are ideal candidate indicators of a broad externalizing liability in their respective domains of measurement.
