PROGRESSIVE FORMATION OF NEURITIC PLAQUES AND NEUROFIBRILLARY TANGLESIS EXPONENTIALLY RELATED TO AGE AND NEURONAL SIZE - A MORPHOMETRIC STUDY OF 3 GEOGRAPHICALLY DISTINCT SERIES OF AGING PEOPLE

Neuronal size and the incidence of neuritic plaques (NPs) and neurofib rillary tangles (NFTs) were morphometrically and quantitatively studie d in the entorhinal cortex of 300 autopsied individuals without dement ia in three geographically distinct series (Brazil, Germany and Japan) , and an additional series including 30 clinically diagnosed Alzheimer 's disease patients. The mean ages at onset of NPs and NFTs were simil ar between the three normal series, and the incidence of NPs and NFTs increased exponentially with age, but at different rates. A correlatio n was found between larger neuronal size and higher incidence of NPs a nd NFTs. Neuronal size distribution largely seemed to account for the differences between the series. While the onset of neurodegeneration m ay be tightly programmed, i.e., in a species-specific manner, our data support the idea that the incidence of NPs and NFTs and the progressi on from NPs to NFTs may vary remarkably, depending on neuronal size.