The work presents the study of neuromorphological changes that have a potential effect on cognitive impairment in type 2 diabetes and Alzheimer's disease. There is strong evidence that diabetes increases the risk of cognitive impairment and dementia. Insulin signaling deregulation may be an important contributing factor in Alzheimer's disease pathogenesis. In addition, diabetes is a risk factor for atherosclerosis and small vessel disease. A growing body of evidence links type 2 diabetes with dementia and neurodegenerative diseases such as Alzheimer's disease. Alzheimer's disease is the most common form of dementia and is characterized neuropathologically by the accumulation of extracellular β amyloid peptide aggregates and intracellular hyper-phosphorylated tau protein. They accelerate inflammatory and oxidative stress processes leading to neurodegeneration. Although the precise mechanism remains unclear, type 2 diabetes can exacerbate these neurodegenerative processes. Brain atrophy, reduced cerebral glucose metabolism and CNS insulin resistance are features of both Alzheimer's disease and type 2 diabetes. The purpose of the study was to determine the pathomorphological changes of the brain in diabetic encephalopathy and Alzheimer's disease and to establish possible common neuromorphological signs that cause clinical symptoms of cognitive deficits. Material and method. We studied medical records of 11 patients with type 2 diabetes and 15 patients with Alzheimer's disease. The mean age of patients with Alzheimer's disease before the onset of the disease was 59.3±6.1 years, and the mean age of patients with diabetes was 51.6±3.4 years. There were 6 patients in the control group without dementia; their average age was 60.5±2.5 years. Autopsy included macroscopic and microscopic study of the brain. Brain tissues were collected at autopsy from different parts of the hemisphere, limbic system, subiculum, hippocampus and cerebellum no later than 8 hours after death. Bits of brain tissue were fixed in a solution of IHC Zinc Fixative (PharMingen, USA), embedded in paraffin and made serial paraffin sections 5 ± 1 μm thick. The slides were stained according to standard methods: hematoxylin and eosin, Thionin by the Nyssl method, impregnated with silver nitrate by the Bielschowsky method and Kahal gold chloride. To identify amyloid, the slides were stained with a Congo red. Histological investigation of the slides was carried out using a microscope Hund H500 (Germany). Results and discussion. Pathomorphological investigation of the brain in individuals with type 2 diabetes showed that the main cyto-angioarchitectonic manifestations of diabetic brain damage were diffuse alteration of the basement membranes and vascular endothelium of the microhemocirculatory bed, both white and gray substances, capillary fibrosis and hyalinosis, pericyte proliferation, accompanied by a sharp disruption on transcapillary transport. There was a combination of acute and chronic processes, reversible and irreversible changes in nerve cells: neuronal swelling, subtotal chromatolysis, karyopyknosis and cytoplasmic homogenization, satellite disease, pericarion enlightenment, tigrolysis, lysis of neurons with the formation of "shadow cells". In areas of chronic ischemia there were neurons or groups of neurons with morphological signs of Alzheimer's neurodegeneration (pathological neurofibrils in the form of tangles), a large number of hematoxylin spheres and single Lafora bodies. Moreover, single terminal plaques were found in the impregnation of silver by the Bielschowsky method. Morphological investigation of the cerebral cortex showed that neuronal loss, acute and chronic dystrophic damage, spongiosis, plaque formation, which caused the main clinical symptoms of Alzheimer's disease, was quite clearly expressed. Atrophy of the cerebral hemispheres in the affected areas was diffuse. Visual assessment of histological structure drew attention to the significant polymorphism of qualitative changes in neurons and the variety of variants of the so-called "senile plaques". In addition, with Alzheimer's disease in almost all cases, cerebral amyloid angiopathy had an effect not only small vessel, but also on vessels of medium caliber in the brain. Alzheimer's neurofibrils and Alzheimer's plaques are typical signs of Alzheimer's disease. Their number varies widely depending on the area of brain studying, the stage of the disease and the duration of clinical symptoms. Conclusion. Thus, the common brain morphological changes in type 2 diabetes mellitus and Alzheimer's disease are formation of neurofibrillary tangles which are thought to contribute to the degradation of the neurons in the brain, congophilic angiopathy of small vessels and vessels of medium caliber. The combination of vascular and neurodegenerative components can mutually potentiate each other, causing clinical symptoms of cognitive deficits.
Keywords: diabetic encephalopathy, Alzheimer's disease, morphologic diagnostic
Full text: PDF (Ukr) 405K