The vascular factor in Alzheimer's disease

What is it about?

Although the etiopathological background of Alzheimer's disease (AD) is mostly associated with the deposition of Αβ-peptide, the hyperphosphorylation of τ protein, the synaptic pathology and the mitochondrial alterations, the vascular factor may play substantial role in plotting the multifactorial pattern of the disease. We attempted to study the blood capillaries in the hippocampus, the acoustic, the visual and the parietal cortex in twelve early cases of Alzheimer's disease. Samples were processed for Golgi silver impregnation technique and electron microscopy. The morphological findings were compared with normal controls. The study of the brain capillaries in cases of AD, revealed numerous fusiform dilatations, tortuosities, abnormal branching and fusion, though the morphometric estimation revealed a decrease of the number of capillaries per mm3 in comparison with normal control brains. The ultrastructural study revealed mitochondrial abnormalities in the endothelial cells of a substantial number of capillaries and marked degeneration of the pericytes. Perivascular microglial proliferation was also prominent in the hippocampus and the parietal lobe. Our findings both in Golgi staining and electron microscopy plead in favor of the essential role that the microvascular alterations may play in the broad pathogenetic spectrum of AD.

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Why is it important?

In the brain cortex the tortuosity of the capillaries and the glomerular loop formation was a frequent finding, associated with twisted capillaries. The distance of two branch points was increased, the branch point density was decreased and the ratio between branch point density and neuron density was decreased. The ratio between branch point density and astrocytic density was substantially decreased.The distance between the branch points was increased, the density of the capillaries per volume wasdecreased and the branch point density was decreased. The capillary tortuosity in the visual cortexwas less prominent than in the hippocampus and the acoustic cortex. The ratio between branch point density and neuronal density was decreased and the ratio between branch points and astrocytes was decreased substantially.The ultrastructural study revealed also a marked degeneration of the pericytes in the hippocampus, the visual, the acoustic and the parietal cortices, in comparison with the normal controls. Large number of pericytes demonstrated increased number of pinocytotic vesicles, large lipid granules and mitochondrial alterations, such as small mitochondria and disruption of the cristae.

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