Forty-seven patients with probable dementia of the Alzheimer type (DAT) and 30 healthy age-matched controls were scanned using [18F]-2-fluoro-2-deoxy-D-glucose on a Scanditronix PC 1024-7B tomograph (inplane resolution = 6 mm, axial resolution = 10 mm). Patients and controls were scanned in the resting state with their eyes patched and ears occluded. The regional cerebral metabolic rates for glucose (rCMRglc) in most major neocortical and subcortical gray matter regions, and certain metabolic ratios (rCMRglc/ calcarine rCMRglc), quantitatively discriminated even the mildly demented patients from healthy controls. The association neocortices showed metabolic abnormalities that were more severe than those in the sensorimotor and calcarine regions. All demented groups showed significant neuropsychological disturbances when compared to healthy controls. These data demonstrated widespread metabolic disturbances, particularly in the association areas, relatively early in Alzheimer's disease, and more profound involvement with disease progression.