With respect to limitations and future directions, the present study’s sample small for studies of gene × intervention interactions, and thus we see relatively small effect sizes. Indeed, too small to study gender differences, despite well-documented gender differences in the amount and type of substance use. The study sample was also largely African-American and socioeconomically disadvantaged. Future studies will require considerably larger and more ethnically and economically diverse samples. This may be best achieved by multi-site studies.
