current or previous alcohol abuse or dependence; subjects were excluded if they reported more than 5 lifetime episodes of using any category of illicit drugs (including sedative-hypnotics, stimulants, cocaine, opioids, hallucinogens, and MDMA) except for marijuana in the case of the smokers. Subjects were required to provide a urine sample to be tested for marijuana, ethanol, amphetamines, opioids, phencyclidine, barbiturates, benzodiazepines, and cocaine (TRIAGE) just prior to imaging. This procedure was required for three reasons: 1) to ensure that subjects did not test positive for other substances of abuse, and 2) to determine whether subjects had used marijuana recently enough to have a positive urine screen, and 3) to encourage subjects, as requested, to abstain from marijuana from the previous evening until arriving at the laboratory, to ensure subjects were not acutely intoxicated at the time of the visit. Subjects were repeatedly reminded that they would be tested for marijuana use upon their arrival at the lab, and were led to believe that we would be able to determine if they had smoked within the previous 12 hours. A portion of the sample was sent to an outside laboratory for quantification of urinary cannabinoid concentration via gas chromatography mass spectrometry
