The substantial confounding by parent substance misuse that we observed also deserves more attention in future studies. The associations between interpersonal violence and drug use outcomes were confounded by parent substance misuse, indicating a domestic environment with multiple forms of inter-related traumas for some children. Future studies should examine the mechanisms by which parental substance use and exposure to traumatic events are associated with adolescent substance use, for example through an influence on social norms and expectancies, modeling behavior, access to illicit substances, or by providing opportunity via low parental involvement or neglect.3,6,33-38 These explorations were beyond the scope of the current study, but future research can inform priorities for intervention in harmful home environments for children and adolescents. By and large, parent substance misuse did not affect the associations between PTEs and drug use. Exceptions included other PTEs and marijuana use, and interpersonal PTEs and other drug use. This could be related to access to drugs in the home or neighborhood, as marijuana and certain types of other drugs may be more easily obtained by adolescents. Alternatively, this statistical
