1. A method for determining an increased likelihood that a subject has Alzheimer's Disease, said method including: imaging an area of the gray matter of the brain of a subject to determine a diffusion tensor image of said area; determining the Fractional Anisotropy from said diffusion tensor image; comparing said Fractional Anisotropy to nonnative data; and identifying an increased likelihood of the presence of AD when said FA is significantly less than said nonnative data.