All procedures were approved by the University of Iowa Institutional Review Board. The procedures were the same in the two in-lab sessions: All participants signed informed consent forms, completed the out-of-scanner cognitive tasks, and underwent MRI scans. The two sessions were approximately two years apart. At the first session, subjects retrospectively reported substance use (non-binge drinking of 1–2 drinks/occasion, standard/extreme bingeing, marijuana and tobacco use) from 6th grade to prior to participating in session 1. Longitudinal data were prospectively collected between session 1 and session 2. For this period, participants reported their substance use via an online survey every six months. For example, six months after the first session, participants completed the first follow-up survey reporting their substance use for each of the prior six months. Specifically, participants reported their monthly frequency (days/month) for alcohol variables. For marijuana and tobacco variables, there were reporting errors due to a misunderstanding of the question format by many participants; therefore, a dichotomized version was used (e.g., months reported using marijuana/tobacco were coded as 1, other months were coded as 0). Longitudinal use for all substance variables were calculated by adding the reported monthly use across all follow-up months.
