Presence of abnormally phosphorylated Tau proteins in the entorhinal cortex of aged non-demented subjects.

An immunoblot study was performed in several cortical samples from non-demented aged controls and compared with those from Alzheimer patients, using antibodies against Tau 55, 64 and 69, which are specific and reliable markers of the neurofibrillary degeneration of the Alzheimer type. The immunodetection of Tau 55, 64 and 69 was positive in all cortical areas from Alzheimer patients, in the entorhinal cortex from each control aged more than 65 but not in cortical samples from younger controls. We demonstrate that the entorhinal cortex is the most vulnerable neuronal population in aging and that the biochemical dysfunctions observed in this area are typically of the 'Alzheimer-type'.