Neuropathological staging of Alzheimer lesions and intellectual status in Alzheimer's and Parkinson's disease patients.

In both Alzheimer's disease (AD) and Parkinson's disease (PD), neurofibrillary tangles (NFT), in contrast to amyloid deposits, show a hierarchical spreading pattern from the allocortex to isocortical association areas with early involvement of the entorhinal region, a major relay station between hippocampus and isocortex. Based on the distribution pattern of NFT in human brain, a neuropathological staging of neuritic AD pathology has been proposed. Comparative studies of this neuropathological staging of neuritic AD changes with psychometrically assessed intellectual status (mini-mental state) in prospective cohorts of 29 aged individuals and 28 PD patients showed a linear correlation of morphological AD staging with the psychostatus in both disorders. The pattern of neuronal degeneration associated with neuritic AD pathology in both AD and PD may be an important basis of cognitive decline in both disorders.