The Addiction Severity Index (McLellan et al. 1980) was administered to all subjects and urine analyses were performed for multiple drugs of abuse. Former severe heroin addicts (African-American, N = 118; Hispanic, N = 142) were long-term heroin addicts who met Federal guidelines for methadone maintenance treatment (1 year or more of daily multiple injections of heroin or other opiates) (Rettig and Yarmolinsky 1995). Subjects in the control group (African-American, N = 80; Hispanic, N = 61) had (1) no illicit drug use for more than 6 months (except cannabis), (2) no excessive use of cannabis (3 or more times per week for more than 4 years), (3) no previous history of alcohol drinking to intoxication (3 or more times per week for 6 months or more), and (4) no alcohol intoxication or illicit drug use (except cannabis) in the last 30 days.
