Recently, using a principal component analysis (PCA) based time-frequency (TF) analysis, Gilmore et al. [144] examined the relationship between the P3, its associated ERO components in a spectrum of externalizing disorders, such as substance use disorders (including alcoholism), ADHD, and conduct disorder in a community-based sample of adolescent males. It was found that 1) P3 and each TF-PCA derived component could successfully discriminate diagnostic groups from controls, and 2) delta components in specific time ranges accounted for variance beyond that accounted for by P3. Further, one delta component was associated with all diagnostic groups, suggesting that ERO delta may represent a more parsimonious endophenotype for externalizing disorders than P3. In another similar study using data from a large twin sample (634 MZ and 335 DZ, male and female same-sex pairs), Gilmore et al. [145], analyzed several electrophysiological measures (the P3, delta and theta ERO components, and resting state beta frequency band) collectively in externalizing disorders. They found these measures (1) were heritable, (2) showed significant phenotypic and genetic correlation with a general vulnerability to externalizing disorders, (3) showed modest phenotypic
