Sibling aggregation for psychopathology in offspring of opiate addicts: effects of parental comorbidity.

Applied a new analytic approach within the high-risk paradigm, the analysis of sibling aggregation, to identify homogeneous subtypes of familial risk for psychopathology and addiction. All sibling pairs participating in a study of offspring of opiate-addicted parents were identified and their aggregation for psychiatric disorders was determined using pairwise odds ratios, an analytic technique used in genetic epidemiology. Sibling aggregation was most notable for depressive and anxiety disorders but only in the presence of comorbid depressive disorders in the parents. Parental comorbid alcoholism did not impact sibling aggregation. We emphasize methodological implications of this approach for addressing issues of phenotypic and etiologic heterogeneity in the study of developmental risk for substance abuse.