The dissertation is devoted to the study of the influence of the rejection of systemic and cerebral hemodynamic, particularly the fluctuation of blood pressure during a year, and episodes of orthostatic hypotension, on cognitive functions in patients with neurodegenerative diseases (Alzheimer's disease, Parkinson's disease) and vascular brain pathology (chronic cerebral ischemia). The study included 159 patients divided into 4 groups: 1 group - patients with Alzheimer's disease (33 patients, 36% men, 64% women), 2 group - patients with Parkinson's disease (35 patients, men 37%, women 63% ), group 3 - patients with chronic cerebral ischemia (54 patients, men 35%, women 65%), group 4 - control (relatively healthy persons) (37 persons, men 38%, women 62%). Depending on the type of the orthostatic reaction each group was divided into subgroups: with orthostatic hypotension (in groups 1, 2, 3), normal orthostatic reaction (in groups 1, 2, 3, 4) and orthostatic hypertension (in group 3). It was found statistically significant correlation between greater changes in systolic blood pressure during a year and the MoCA scores, FAB scores, 12 Words Memory Test ( p = 0.33, p = 0.05), Semantic Verbal Fluency Test (p = 0.37, p = 0.05), Clock Drawing Test. The most vulnerable were domains of executive functions (p = 0.05), memory (p = 0.05), attention (p = 0.05). It was found the impairment of cognitive functions in the domains of memory (p<0.05), executive functions (p <0.05) in Over-Dipper patients according to the ambulatory blood pressure. The impairment of cerebral vasoreactivity was found during the hypercapnia test and the hypocapnia test, which correlate with impairments in domains of executive functions (p<0,05) and language (p<0,05), memory (p<0,05 ), attention (p<0,05). Patients with Alzheimer's disease and orthostatic hypotension have statistically significant lower scores in the domains of memory (p<0,05), attention (p<0,05), language (p<0,05) Patients with Parkinson's disease and orthostatic hypotension have statistically significant lower scores in the domains of memory (p<0,05), attention (p<0,05), executive functions (p<0,05), intellection (p<0,05). Patients with chronic cerebral ischemia and orthostatic hypotension have statistically significant lower scores in the domains of orientation to time (p<0,05), orientation to place (p<0,05) attention and calculation (p<0,05), memory(p<0,05), language (p<0,05), executive functions (p<0,05). MoCA (p<0,05), Clock Drawing Test (p<0,05), 12 Words Memory Test (p<0,05), Semantic Verbal Fluency Test (p<0,05), Semantic Verbal Fluency Test (p<0,05) were found as useful for evaluating the cognitive decline in patients with orthostatic hypotension.
