While most of the above discussion is very general and applies equally well to all traits, this review will examine substance use disorders, which are especially challenging because of their complexity and heterogeneity. Unlike blood pressure or obesity, which can be readily studied in both mice and humans, substance use disorders are uniquely human and cannot be directly modeled in non-humans. Substance abuse develops slowly over years or decades whereas phenotypes measured in mice typically are performed in days or weeks. While the difference in life span of humans and mice confounds any direct temporal comparisons, in general animal models are intended to study specific aspects of substance use disorders (e.g., locomotor response to a stimulant drug) rather than the full disorder. Several excellent reviews have recently addressed the subject of animal models of substance use disorders (Crabbe et al. 2011; Stephens et al. 2011). In this paper, we will explore examples of genetic studies that have integrated findings from both mice and humans that enrich the understanding beyond what could be attained by studies with either species alone. We have not attempted to be exhaustive, but have instead chosen examples that illustrate different approaches.
