Late-onset sporadic progressive subcortical gliosis.

We report two sporadic cases of progressive subcortical gliosis (PSG) with onset after age 60. The presentation included slowly progressive dementia with memory loss, geographic disorientation, and personality change. Both were diagnosed clinically as Alzheimer's disease (AD) and both met NINCDS-ADRDA criteria for probable AD. Autopsy revealed generalized atrophy, predominantly involving the white matter of the frontal and temporal lobes. Microscopically, prominent fibrillary astrocytosis was present in the subcortical white matter and in the subpial and deep layers of the overlying cerebral cortex. Mild cortical neuron loss accompanied the gliosis, but no myelin loss was evident. Amyloid deposits and neuronal cytoskeletal inclusions were absent.