- While the reliability of assessment instruments designed for use with adults is well established, much less is known about the adequacy of these instruments for adolescent substance abusers. As part of a comprehensive intake evaluation, the Inventory of Drug Use Consequences (InDUC) was administered both to forty adolescents assigned to a probationary substance abuse treatment program and to one of their parents. The correlation was statistically significant between Parent and Adolescent InDUC score(s), but the interrater reliability was relatively low. IQ scores and level of substance use were considered as moderator variables, but neither showed a significant effect. History of head injury, however, significantly moderated this relationship; those adolescents reporting no history of head injury showed little correspondence with Parent InDUC Score(s), whereas those adolescents with a history of head injury showed significant correlations with parent InDUC scores. This suggests that a history of head injury may affect the way in which adolescents perceive substance-related consequences.