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Neurons and neurofibrillary tangles in the hippocampal cortex in familial and sporadic Alzheimer's disease

Hippocampal pathology was morphometrically studied in six early onset familial Alzheimer's disease (FAD) patients and the results were compared with six early onset sporadic Alzheimer's disease (SAD) patients. Unaffected neurons, intracellular neurofibrillary tangles (I‐NFT) and extracellular neurofibrillary tangles (E‐NFT) were evaluated on the same sections in eight subdivisions of the hippocampal cortex, using Gallyas technique modified by a direct application of hematoxylin and eosin stain (Gallyas‐HE stain). The subdivisions were CA4, CA3, CA2, CA1, prosubiculum (PRO), subiculum and presubiculum (PRE), parasubiculum (PARA) and entorhinal cortex (ENT). Unaffected neuron densities in CA2, CA1 and PRE in FAD were significantly lower than those in SAD. In contrast, in ENT the unaffected neuron density in FAD was greater than that in SAD, but the difference was not significant. Extracellular neurofibrillary tangle densities in the subregions, other than ENT in FAD, were greater than those in SAD, while the E‐NFT density in ENT in FAD was lower than that in SAD. Neurofibrillary tangles (I‐NFT plus E‐NFT) densities in CA3, CA2, CA1 and PRO in FAD were significantly greater than those in SAD. These data suggest that cornu ammonis is affected more severely than is the ENT in early onset FAD. These findings indicate that hippocampal pathology in early onset FAD may be qualitatively as well as quantitatively different from that in early onset SAD.