Assessment of biomarkers in biological fluids and neuroimaging changes in patients with Alzheimer’s disease and glaucoma

Introduction. Alzheimer’s disease (AD) and primary open-angle glaucoma (POAG) are gradually progressive neurodegenerative diseases leading to disability. According to literature data, POAG can be a predictor of AD development. Early diagnosis of these diseases contributes to a timely initiation of treatment and, as a result, a reduction in the disability of patients. Objective. To study biomarkers of early diagnosis in biological fluids and neuroimaging changes based on the results of MR morphometry in patients with AD and POAG and to conduct their comparative analysis. Materials and methods. In total, 90 patients with proven diagnosis of AD (group 1) and POAG (group 2) were examined. The study participants were divided into two groups according to their diagnosis: group 1 — 45 patients (9 (20%) men and 36 (80%) women) with AD; group 2 — 45 people (17 (37.8%) men and 28 (62.2%) women) with POAG. Neuropsychological testing included Mini-mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and a ten-words recall test. The beta-amyloid (Aβ) Aβ42/Aβ40 ratio in the blood and sirtuin Sirt1, 3, 5, and 6 in saliva were assessed by enzyme immunoassay (ELISA). In addition, MR morphometry of the brain was performed. Results. In group 1, cognitive impairments (CI) reaching the degree of dementia were detected; in group 2, pre-demential CI were observed ( p < 0.001). According to the neuropsychological examination, similar changes were noted in both groups, in particular, memory impairment of the hippocampal type. The results of the blood and saliva ELISA with the determination of biomarkers in the groups under comparison did not reveal statistically significant differences. At the same time, the parameters of both volumes and thicknesses according to MR morphometry were lower in group 1 ( p < 0.05), which may reflect neurodegenerative progression. In group 1, a direct correlation was found between a decrease in the saliva level of Sirt3 and a deterioration in direct reproduction (fifth reproduction) according to the ten-words recall test ( R = 0.43; p = 0.003). Correlations between changes in neuropsychological parameters and MR morphometry data, including a decrease in the volume of the entorhinal cortex, were noted in both groups. In groups 1 and 2, a decrease in the Aβ42/Aβ40 ratio in blood plasma was associated with a decrease in the thickness or volume of the entorhinal cortex, which is common for both groups with different CI severity. Taking into account the association with neuropsychological and blood parameters, including in patients with pre-demential CI from the POAG group, the determination of the volume and thickness of the entorhinal cortex can be regarded as a significant early marker of the neurodegenerative process. Conclusions. The established association between the volume and thickness of the entorhinal cortex with neuropsychological and blood parameters, including in patients with pre-demential CI from the POAG group, makes the determination of the volume and thickness of the entorhinal cortex a significant early marker of the neurodegenerative process. A comprehensive assessment of the results obtained by neuropsychological, laboratory, and neuroimaging diagnostic methods, as well as the search for diseases associated with the development of AD, such as POAG, are promising research areas, requiring larger cohort studies.