An investigation of female adolescent twins with both major depression andconduct disorder

Objective: Conduct disorder (CD) and major depression (MDD) frequently co-o ccur in adolescents, but little is known about the characteristics and func tioning of youths, especially females, with both disorders. This study desc ribes the functioning of female adolescents with histories of both CD and M DD. Method: Subjects were selected from an epidemiological sample of 17-yea r-old female twins based on having a lifetime DSM-III-R diagnosis of MDD an d/or CD; control subjects had no history of either disorder. Results: In ne arly all domains examined, including measures of academic success (includin g academic achievement and school adjustment), personality, quality of peer relationships, and high-risk behavior (including substance dependence and early sexual experience), main effects of one or both disorders were found and related to impaired functioning. In addition, interaction effects were found in the areas of substance dependence symptoms (for all classes of sub stances), negative school-related events, and a personality-based predispos ition not to experience positive emotions, indicating that those with both diagnoses were especially impaired. Conclusions: In some domains, histories of MDD and CD interact and relate to particularly severe problems. The imp lications of these findings far research and treatment, including the high likelihood of substance and school adjustment problems in these youths, are discussed.