Demographics included age, sex, race/ethnicity, education, and employment status, which were assessed by the CTN common demographic form. Past-year substance use and disorders (abuse or dependence on alcohol, cannabis, cocaine, inhalants, amphetamines, sedatives, hallucinogens) were assessed by the DSM-IV Checklist (Hudziak et al., 1993). At intake, all participants were administered the DSM-IV Checklist by CTN-affiliated trained interviewers (research staff who completed training for administering the DSM-IV Checklist) to assess substance use in the past year. Participants who responded affirmatively to the initial substance use question (“Have you ever used [NAME OF THE SUBSTANCE] in the past 12 months?”) then were assessed for seven substance-specific dependence criteria. Endorsement of at least three of the seven DSM-IV dependence criteria resulted in a dependence diagnosis (tolerance, withdrawal, substance often taken in large amounts/for longer periods of time, persistent desire or unsuccessful attempt to cut down, a great deal of time spent in activities necessary to get the substance, important activities given up, continued substance use despite knowledge of having recurrent physical or psychological problems). Following DSM-IV logic, individuals who did not meet the criteria for a SUD were then assessed for abuse.
