Population imaging in neuroepidemiology.

Neuroepidemiologic studies have traditionally focused on studying associations between determinants and neurologic outcomes, while treating the pathway in between both as a "black box." With the rise of noninvasive, advanced neuroimaging techniques, it has become possible to directly study brain changes occurring in this "black box." This importantly aids to unravel disease pathways, find new markers of disease, or identify subjects at risk of disease. Imaging in neuroepidemiologic studies is also called population neuroimaging. This chapter discusses the rationale of population neuroimaging, the different imaging modalities that can be applied, and the various ways to extract visual or quantitative information from these images. Population neuroimaging is a fast-progressing field, partly due to new techniques and partly due to the growing need for collaboration, harmonization, and standardization among studies. Considerations for future applications of imaging in neuroepidemiology are discussed against this background.