The Addiction Severity Index (ASI) (McLellan et al., 1980) was administered to and urine analyses were conducted for multiple drugs of abuse in all subjects. Former severe heroin addicts met Federal guidelines for methadone maintenance treatment (one year or more of daily multiple injections of heroin or other opiates) (Rettig and Yarmolinsky, 1995). Control subjects had no history of alcohol or illicit drug use (illicit drug use or drinking to intoxication three or more times per week for 6 months or more), no use of cannabis (three or more times per week) for more than 4 years, and no current alcohol or illicit drug use (one or more instance of drinking to intoxication or any illicit drug use (except for possible cannabis use up to 12 days) in the last 30 days).
