At their initial and follow-up visits, parents and their children were interviewed by a laboratory research psychologist or other trained researcher using a structured interview (Kiddie Schedule for Affective Disorders, K-SADS) to assess current and lifetime history of psychiatric disorders (Kaufman et al., 1997). Using the probe questions of K-SADS-PL, the interviewer questioned each participant about age at first regular use of alcohol or drug and recency and frequency of use for each substance. No participant endorsed regular use of alcohol or any substance at baseline or follow-up. One parent of each child was also interviewed at each session and confirmed, without knowledge of the child's report, a negative history of regular alcohol and drug use. No further information on alcohol or drug misuse was obtained because there were no endorsements of gate (i.e., probe) questions. Other exclusionary criteria were history of loss of consciousness > 30 minutes or central nervous system diseases. Parents provided information to determine socioeconomic status (Hollingshead, 1975). Intelligence quotient (IQ) of each adolescent was measured with the Peabody Picture Vocabulary Test (Dunn and Dunn, 1997).
