The striatum plays a central role in the limbic system and the cholinergic system, which are both affected in AD. Therefore the striatum can be considered a key candidate structure to be affected... Show moreThe striatum plays a central role in the limbic system and the cholinergic system, which are both affected in AD. Therefore the striatum can be considered a key candidate structure to be affected early in the disease. Part one of this thesis bundled the results of several volumetric and morphometric structural MRI studies of the striatum in older people and especially in patients with AD. Identifying pathological (focal) brain atrophy is, however, complex and a simple estimation of brain structure volumes of an individual patient does not lead to a diagnosis but needs to be assessed relative to group volumes and premorbid brain size. Therefore, in part two of this thesis two large population studies were included that focused on improving our understanding of the physiologic variability of brain structure and degeneration. Show less