Pyramidal nerve cell loss in Alzheimer's disease.

Loss of the large pyramidal cells of the association neocortex and hippocampus, along with plaques and tangles, is fundamental to the neuropathology of Alzheimer's disease. The extent of Alzheimer-specific cell loss, relative to controls, is age-dependent with maximal losses in younger subjects though, because of the (additive) effects of 'normal' ageing on such cells, the absolute loss remains constant at all ages. The cause of the cell loss remains unknown but probably relates to neurofibrillary degeneration through a crowding out of organelles and a disruption of intracellular transport; oxidative stress may also contribute. The degree of clinical dementia correlates well with the extent of pyramidal cell loss.