Temporal sequence of plaque formation in the cerebral cortex of non-demented individuals.

One of the hallmarks of Alzheimer's disease is the presence of argyrophilic plaques (arg-P) accompanying dementia and other forms of cognitive alterations. In the present investigation 195 non-demented, cognitively normal patients were grouped according to the presence or absence of critical coronary artery disease (cCAD), defined as a 75% or greater stenosis of one of the epicardial arteries. None of the subjects had significant cerebral vascular disease. The parahippocampal gyrus (PHG) and frontal pole were analyzed for the presence of arg-P, A4 deposition, ALZ-50 immunoreactive (IR) neurons and neuropil threads (NT). Individuals with cCAD have a significantly greater incidence of plaques than non-heart disease (non-HD) subjects. Every cCAD subject had ALZ-50 IR neurons in the PHG and a greater incidence of NT as compared to the non-HD subjects. Every subject with plaques also had IR neurons and NT in the PHG. Based on the presumption that early neurodegeneration labeled by ALZ-50 antibody and amyloid deposition are in some way linked, then the sequence of plaque formation is initiated by the presence of ALZ-50 IR neurons followed in order by NT, A4 deposition and diffuse form arg-P.