Neuropathological indexes of Alzheimer's disease in demented and nondemented persons aged 80 years and older

Presence of axonal paired helical filament-tau in Alzheimer's disease: submicroscopic localization

While normal adult tau protein is found typically in axons, paired helical filament (PHF) tau has been shown immunohistochemically to be in the somatodendritic compartment in Alzheimer's disease (AD). The small amount of PHF-tau (8-11%) found in white matter with immunochemical methods is shown here by immunoelectron microscopy to be located in axons. It is localized to straight filament variants of PHFs. The small amount of PHF-tau in white matter, therefore, appears not to result from the contamination of immunochemical preparations but to be an integral constituent of affected axons in AD.

Computed detection and quantitative morphometry of Alzheimer senile plaques

Senile plaques (SP) are the most characteristic neuropathologic lesions of Alzheimer's disease (AD) and studies of plaque cortical distribution, density, and morphology may lead to new information about the origin and pathogenesis of this disease. We have developed an automated computer image analysis program to detect SP (including diffuse and mature forms) and to measure SP size, shape, and fractional area or load in digital micrographs of silver-stained tissue sections. The plaques are detected with adaptive thresholding, requiring no user interaction. Measures of SP size, morphology, and load are readily calculated from the pixel values in the detected SP features. These measurements are achieved accurately and exhaustively, and this method offers an alternative to manual SP counting. We demonstrate its application to 4 cases spanning the full range of the severity of the disease.

Neuropathological changes in the cerebral cortex of 1258 cases from a geriatric hospital: retrospective clinicopathological evaluation of a 10-year autopsy population

To examine the neuropathological and clinical characteristics of cerebral aging, we evaluated retrospectively a non-selected autopsy population of 1258 patients from the Geriatric Hospital of the University of Geneva School of Medicine. The prevalence of Alzheimer's disease increased with age below 90 years of age. In the nonagenarians and centenarians, there was a decline in the number of affected cases. The distribution with age of neurofibrillary tangles and senile plaques varied among the cortical areas studied. The CA1 field of the hippocampus and the inferior temporal cortex displayed increasing densities of neurofibrillary tangles with age, whereas the superior frontal and the occipital cortex were relatively spared, especially in patients in their tenth and eleventh decade. The percentage of cases presenting with senile plaques in the neocortex and hippocampal structure increased with age with a marked predominance of cases with moderate to high senile plaque densities. Neurofibrillary tangles were often observed in the CA1 field and the inferior temporal cortex of non-demented individuals and were present in most cases with Alzheimer's disease. Conversely, the involvement of the superior frontal and occipital cortex was moderate even in demented patients. The distribution of senile plaques was homogeneous in all of the neocortical areas independently of the clinical diagnosis. Moreover, there was no correlation between the presence of neurofibrillary tangles and senile plaques in the cerebral regions studied. These results indicate a differential topography of neurofibrillary tangles and senile plaques, and suggest that overt clinical signs of Alzheimer's disease are linked to the progression of the neurodegenerative process in neocortical areas.

Two types of dystrophic neurites in senile plaques of Alzheimer disease and elderly non-demented cases

Senile plaques (SPs) occur profusely in brain tissue of Alzheimer disease (AD) cases, and sparsely in brain tissue of elderly normals. Two types of dystrophic neurites (DNs) have been identified in SPs. Type 1 are the classically described elongated forms. Type 2 are globular in shape. Type 1 DNs are stained immunohistochemically by antibodies to A68 protein, other forms of phosphorylated tau, and N-terminal epitopes of amyloid precursor protein (APP), as well as an antibody which preferentially recognized conjugated ubiquitin. Type 2 DNs are stained immunohistochemically by antibodies to chromogranin A and C-terminal epitopes of APP, as well as an antibody which preferentially recognizes free ubiquitin. SPs of AD cases usually contain a mixture of type 1 and type 2 DNs. However, in the neocortex of elderly normals, which have few neurofibrillary tangles and neuropil threads, the DNs in the SPs are restricted to type 2. These data suggest that SPs containing only type 2 DNs may be benign, and independent of neurofibrillary pathology.

A quick silver method for senile plaques and neurofibrillary tangles in paraffin sections

A new silver method for senile plaques and neurofibrillary tangles (NFT) in paraffin sections is presented. This new technique is rapid in execution (15 min) and reveals senile plaques of all morphological types as well as NFT. The silver staining is spatially congruent with immunocytochemical staining for the beta-amyloid peptide (A beta) in adjacent sections.