Present results suggest that abnormalities in these two delta components, particularly PC3 with its unique relationship across disorders, may play an important role in the association between P3-AR and externalizing psychopathology. Previous findings have shown reduced power in P3-related delta activity to be associated with alcoholism and risk of developing alcoholism (Jones et al., 2006; Kamarajan et al., 2006; Rangaswamy et al., 2007). Further, some research has suggested that the activity revealed by time-frequency analyses may be closer to gene function than are clinical and cognitive measures (Begleiter & Porjesz, 2006). Thus, the aforementioned associations between P3-related delta and theta, alcohol and drug use disorders, and the CHRM2 gene (Dick et al., 2008; Jones et al., 2004; Luo et al., 2005; Porjesz & Rangaswamy, 2007; Wang et al., 2004) suggest a genetic component potentially relevant to the etiology of substance use disorders and externalizing psychopathology – a genetic component closely linked to the P3-related TF components found in the present study.
