(300 WORDS MAX) This study aims to determine whether a new non-invasive neuroimaging biomarker providing information on the tissue integrity of brain white matter is useful for the early diagnose and monitoring of Alzheimer's disease (AD). So far, structural MRI measures of brain volumes are used to predict the onset of AD and monitor the progression of the disease. We have recently developed a new MRI method that measures diffusion and is specifically sensitive to microstructural changes in the brain such as demyelination and loss of fibers in the brain white matter. We hypothesize that this method will be a sensitive marker for AD prior to the sensitivity of conventional MRI methods. Therefore, we plan to perform a cross-sectional study in a group consisting of 1) patients with AD, 2) individuals with mild cognitive impairment (MCI) that are likely to convert to AD, and 3) healthy elderly controls in which we will test if our new markers are able to reliably discriminate between those three groups. In addition, we will compare our new MRI method with structural MRI in order to see which method is more sensitive to changes in early AD. The essential innovation in this proposal is the use of diffusion kurtosis imaging (DKI), currently the only clinically available method that provides specific information on the brain white matter integrity such as axonal density and degree of myelination. Our DKI MRI method is a clinically feasible method that requires no contrast or ionizing radiation and takes less than 15 minutes. MRI is currently widely available and our technique is easy to implement, making it an ideal biomarker for early diagnose of Alzheimer's disease and testing of new treatments.