A breathalyzer test to screen for alcohol (Alco-Sensor IV, Intoximeters, Inc., Saint Louis, MO) and a saliva screen for drugs (Oral Fluid Drug Screen Device, Innovacon, Inc., San Diego, CA) was performed for all subjects on each testing day, with negative findings required for participation (no subjects failed screens). Participants received monetary compensation for their participation. Exclusion criteria for all groups included: a) significant history of head trauma or cranial surgery; b) current or lifetime history of diabetes, stroke, or hypertension that required medical intervention; c) current or lifetime history of a significant neurological disorder; d) clinical or laboratory evidence of active hepatic disease; e) clinical evidence for Wernicke–Korsakoff syndrome, and f) lifetime diagnosis of schizophrenia or schizophreniform disorder (assessed by the C-DIS). For this current study, subjects with lifetime dependence on opiates or marijuana were excluded.
