Neurofibrillary changes confined to the entorhinal region and an abundance of cortical amyloid in cases of presenile and senile dementia.

Cases of old-aged demented individuals exhibited abundant cortical amyloid deposits but only small numbers of neurofibrillary changes. Neuritic plaques were rare or absent. Neither Ammon's horn nor isocortex revealed sufficiently large numbers of tangles to permit the diagnosis of fully developed Alzheimer's disease. Dense accumulations of neurofibrillary tangles and neuropil threads occurred only in layer Pre-alpha (II) of the entorhinal region. This pattern of cortical destruction may represent a variant of Alzheimer's disease or an initial stage of this disorder.