Biomarkers hold immense promise for the early detection of disease. Unlike other disorders like diabetes and heart disease where a limited number of biological markers are at hand that allow the physician to come up with a reliable diagnosis, there are currently no such markers available for affective disorders. As in any other disease area a major goal is therefore the identification of early markers that can categorize subsets of subjects in a consistent manner. This will allow a more precise definition and categorization of affective disorders and in turn facilitate investigations of the pathogenesis of the diseases and enhance our ability for treatment. This edited volume will not only address the area of affective disorders but also other brain disorders that are neurological in nature, including Multiple Sclerosis and Alzheimer Disease.