The Virginia Twin Study of Psychiatric and Substance Use Disorders (VATSPSUD) was ascertained through the Mid-Atlantic Twin Registry at Virginia Commonwealth University with minimal inclusion criteria: birth in the Commonwealth of Virginia within the target age cohort. In this data set, we focus on 2231 self-identified European-American male subjects. Drug use disorder is operationalized as lifetime dependence on any illicit substance (9.68%). Previous work in this sample has demonstrated a satisfactory genomic inflation factor of .99 (20).
