Proof of concept C.M. Roe, PhD, M.A. Mintun, MD, N. Ghoshal, MD, PhD, M.M. Williams, MD, E.A. Grant, PhD, D.S. Marcus, PhD and J.C. Morris, MD From the Alzheimer's Disease Research Center (C.M.R., M.A.M., N.G., M.M.W., E.A.G., D.S.M., J.C.M.), Departments of Neurology (C.M.R., N.G., J.C.M.), Radiology (M.A.M., D.S.M.), Medicine (M.M.W.), Psychiatry (M.M.W.), Pathology and Immunology (J.C.M.), Phys