Six participants were excluded for admitted current drug use or having a positive breathalyzer test. The final diagnostic groups for analysis resulting from EEG processing and diagnostic inclusion/exclusion criteria were as follows: ADHD (n = 25), ODD (n = 41), CD (n = 115), AAB (n = 60), AlcD (n = 154), NicD (n = 153), DrgD (n = 70), and externalizing diagnosis-free controls (n = 93). Composite variables were also made based on the presence of any childhood disruptive disorder (Any-CDD; n = 133), any substance use disorder (Any-SUD; n = 220), or any of the seven disorders studied here (Any-EXT; n = 245). Sixty-six individuals with usable ERP data did not meet inclusion criteria for either diagnostic or control groups (e.g., those without history of definite externalizing disorder but with a diagnosis of substance abuse). However, a recent paper by Yoon et al. (2013) using the same sample and assessment with identical exclusion criteria has shown that included and excluded individuals did not differ based on P3 amplitude or externalizing psychopathology at their original (age-17) assessment.
