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 and genetic correlation with each other, and (4) were sensitive to genetic effects that differed as a function of gender. These relationships suggested that these endophenotypes were likely tapping into electrophysiological processes and genes that were both common across them and unique to each. All these electrophysiological endophenotypes were highly relevant to a biological vulnerability to externalizing psychopathology. These two studies further indicated that delta and theta EROs are useful endophenotypes not only specifically for alcoholism but also for the spectrum of related externalizing disorders that includes alcoholism.
