A twin study examining the role of multiple traumas in the sexual assault and substance abuse dialectic

More than 20 million people in the United States have survived a completed or attempted rape in their lifetimes, and approximately 22.5 million people have problematic substance use. The interplay between these two issues is complex: a history of sexual assault predicts substance abuse and, conversely, substance abuse increases sexual assault risk. This secondary analysis of the Virginia Twin Study of Psychiatric and Substance Use Disorders data for White female-female twins (n=1,497) examines the role of multiple traumas in the sexual assault/substance abuse association. Structural models were used to examine pathways between child sexual abuse (CSA), other traumas, familial factors, social support, psychiatric disorders, and substance abuse. The models also integrate the ACE twin design to estimate genetic, shared environment, and individual-specific environment contributions to liability for psychiatric disorders and substance abuse. Study findings support an interplay between childhood trauma, development of substance abuse and psychiatric disorders, and risks for adult victimization. The findings also support assertions that multiple traumas may increase likelihood for substance abuse and psychiatric disorders, and that these disorders predict risk of adult sexual assault. Across all ACE models, both genetics and common environment produced consistently large estimates of influence on liability for substance abuse. Individual-specific environment played a smaller role but was also often significant, and the pathways from trauma variables to both psychiatric disorders and substance abuse tended to be strong. This supports an interaction between genes and environment/experience in which genetic predisposition, though present, may or may not be activated depending on life experiences. Study findings underscore the need for integrated services for clients with history of multiple traumas and for clients with trauma history and substance abuse or psychiatric disorders.