Zerhouni73 identified translational studies as a key priority for the National Institute of Health, and the importance of twin studies of endophenotypes for clinicians and those outside the genetic field should not be overlooked. Translational research is normally taken to mean “from science to bedside.”74 However, with research that does not involve clinical trials or direct clinical interventions, such as quantitative genetic studies, it is important to take a broader view. The road from science to bedside may involve many steps, and it is necessary to understand the role of research findings to yield individual health benefits. Much endophenotype research is concerned with identifying objective measurements that can be used as measurements of ADHD. Such assessments and their biological markers may provide powerful phenotypes for future studies that will enhance the lives of those with ADHD. For example, molecular genetic and functional magnetic resonance imaging studies may improve the characterization of biological pathways between genes, brain, and behavior. This improvement may in turn help to identify more homogenous clinical subgroups that differ in their responses to treatment. In addition, although
