Neuropathology of aging.

The brain undergoes many gross and histopathologic changes with advancing age. Some of the changes seen with aging are also found in demented individuals, especially patients with Alzheimer's disease. The extent to which Alzheimer's disease and aging are truly different processes remains to be determined. The morphologic features that seem most clearly to distinguish between aging and Alzheimer's disease are the neurofibrillary tangles and senile plaques. The distinction can be further refined by determining the immunocytochemical and ultrastructural composition of the degenerating nerve processes in the neuritic plaques.