There are inherent limitations with post-mortem human brain studies with confounds such as drug use history, co-morbidity with psychiatric disorders, and lifestyle characteristics that are difficult to validate. In addition, studies of the post-mortem human brain only allow evaluation at a fixed time point; thus following the trajectory of neurobiological measures with behaviors over time is not feasible and it is impossible to know the state of these systems prior to drug use. Nevertheless it is critical to expand our understanding of what is a quintessential human condition by the direct study of the human brain and that can provide a foundation for future experimental animal models in which causal relationship to specific addiction-related behaviors can be determined.
