BUTYRYLCHOLINESTERASE REACTIVITY DIFFERENTIATES THE AMYLOID PLAQUES OF AGING FROM THOSE OF DEMENTIA

In a sample of consecutively received, 4 demented and 4 age-matched no ndemented brains, the total cortical area covered by plaque-like A bet a amyloid and butyrylcholinesterase deposits was measured at two regio ns of the temporal cortex with the help of computed densitometry. Deme nted as well as age-matched nondemented brains contained A beta and bu tyrylcholinesterase-positive plaques. The total cortical area covered by the A beta precipitates was higher in demented individuals but ther e was overlap with the values seen in the specimens from nondemented i ndividuals. The proportional plaque area displaying butyrylcholinester ase reactivity was very significantly and fivefold to sixfold higher i n the demented than in the nondemented group and there was no overlap between the two populations. Diffuse A beta deposits in nondemented el derly brains may represent a benign or preclinical stage of plaque dep osition with relatively little pathological effect on brain tissue and mental function. Our results suggest that the progressively more exte nsive butyrylcholinesterase reactivity of plaques may participate in t heir transformation from a relatively benign form to pathogenic struct ures associated with neuritic degeneration and dementia.