The environmental context of SUD also has moderate-to-strong involvement in substance use outcomes. Consequently, genetic regulation of biological changes preceding and as a consequence of SUD require additional clarification as substance use can be a means by which the individual copes with environmental risk factors. SUD can also be considered to be an environmental exposure when the brain is exposed to commonly abused substances. Future studies of epigenetic mechanisms, such as methylation and the role of miRNAs, could determine the exact role of the environment on patterns of differential gene expression in neurobiological systems of interest that can precipitate a SUD.
