Morphometric analysis of standardized gross cerebral slices from 16 patients with end-stage Alzheimer's disease (AD), 14 controls without neuropathological lesions or neurological disease, and 4 neurologically intact nondemented patients with histopathological lesions of AD was used to measure cross-sectional areas of cerebral cortex, white matter, subcortical nuclei, and the ventricular system. In AD, there was global cerebral atrophy of both cortex and white matter, selective atrophy of the amygdala and hippocampus, and ex vacuo hydrocephalus. In addition, in half the cases of AD, white matter atrophy was associated with overt histopathological evidence of patchy rarefaction of fibers and gliosis. Patients with preclinical AD had prominent and selective shrinkage of white matter comparable to that observed in AD, yet their cortical areas were normal. These observations suggest that white matter degeneration is an intrinsic component of AD. Moreover, its presence in preclinical AD where cortical atrophy is not evident indicates that cytoskeletal abnormalities associated with axonal degeneration may precede and perhaps cause the cortical atrophy observed in clinically manifested AD.