Parents and youth completed screening interviews, including the Diagnostic Interview Schedule for Children Predictive Scales (Lucas et al., 2001), to rule out psychiatric disorders and other exclusions listed above. Parents provided socioeconomic status background information which was converted to a Hollingshead Index of Social Position score (Hollingshead, 1965), and completed the Child Behavior Checklist (Achenbach and Rescorla, 2001) yielding continuous indices of internalizing and externalizing psychopathological syndromes normalized by age and gender. Pubertal staging was assessed with the Pubertal Development Scale (Petersen et al., 1988), and calculated separately by gender. The Beck Depression Inventory (Beck, 1978) and Spielberger State Trait Anxiety Inventory (Spielberger et al., 1970) assessed mood state at the time of scanning. Premorbid intellectual functioning was estimated by the Wechsler Abbreviated Scale of Intelligence (Wechsler, 1999) Vocabulary and Block Design subtests. Immediately preceding the scan session, subjects submitted samples for breathalyzer and urine toxicology analyses to ensure against recent intoxication, and were administered a 28-day Timeline Followback (Sobell and Sobell, 1992) to document patterns of recent substance use.
