Ultrastructural features of the brain of patients with cognitive impairment in Alzheimer’s disease and vascular dementia

BACKGROUND: Nowadays, due to the increase in life expectancy, the problem of cognitive disorders, quite often found in elderly people and being a formidable syndrome of a number of neurodegenerative diseases, is extremely relevant. According to epidemiological data, the most common causes of cognitive dysfunction are Alzheimer’s disease and cerebrovascular diseases, accounting for about 90% of all cases. AIM: to investigate the morphological features underlying the development of cognitive disorders in Alzheimer’s disease and cerebrovascular pathology. MATERIALS AND METHODS: According to our developed and patented method of preparation of sectional material for electron microscopy а detailed study of the brain of elderly patients with Alzheimer’s disease and cerebrovascular pathology was carried out using electron microscopy on autopsy material. RESULTS: Electron microscopy of the brains of patients with Alzheimer’s disease often reveals large extracellular reticulate-fiber structures closely adjacent to myelin fibers, which are part of a fibrous plaque. In vascular dementia, irregularly shaped hyperchromic masses with heterogeneous contents are found in the neuropil, which may represent future so-called “diffuse” plaques. In Alzheimer’s disease, fragments of future “diffuse” plaques are also observed in the cytoplasm of some cortical oligodendrocytes. In all deceased with Alzheimer’s disease, synaptic changes were found in the form of roughly granular disintegration of the entire synaptocomplex, i.e., synaptic vesicles, mitochondria, and the synaptic cleft proper. CONCLUSION: This study provides an opportunity to take a new look at some questions of etiology and pathogenesis of such a disease as cognitive disorders, which is not easy to diagnose and treat.