RESUMEN
Neuronal size and the incidence of neuritic plaques (NPs) and neurofibrillary tangles (NFTs) were morphometrically and quantitatively studied in the entorhinal cortex of 300 autopsied individuals without dementia 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 similar between the three normal series, and the incidence of NPs and NFTs increased exponentially with age, but at different rates. A correlation was found between larger neuronal size and higher incidence of NPs and NFTs. Neuronal size distribution largely seemed to account for the differences between the series. While the onset of neurodegeneration may be tightly programmed, i.e., in a species-specific manner, our data support the idea that the incidence of NPs and NFTs and the progression from NPs to NFTs may vary remarkably, depending on neuronal size.
Asunto(s)
Envejecimiento/psicología , Encéfalo/patología , Neuritas/ultraestructura , Ovillos Neurofibrilares/patología , Neuronas/ultraestructura , Adulto , Anciano , Encéfalo/citología , Encéfalo/ultraestructura , Brasil , Núcleo Celular/ultraestructura , Tamaño de la Célula , Femenino , Alemania , Humanos , Japón , Masculino , Persona de Mediana Edad , Degeneración Nerviosa/fisiología , Tamaño de los Órganos/fisiologíaRESUMEN
This morphometric, quantitative and correlative multivariate study of the hippocampal formation in human brains from two distinct normal aging populations provides an additional support to the notion that neuritic plaques (NP) are an earlier stage of the pathological process underlying neurofibrillary tangle (NFT) formation. It is shown that the rate of transformation of NP-affected neurons into NFT-bearing neurons may vary remarkably between distinct populations. In addition, it is put forward that different rates of neuronal degeneration may be one of the explanations for the existence of conflicting hypotheses regarding pathogenesis of NP and NFT and the relationships of these important histological markers to psychical deterioration.