Abstract This article is based on a review of the literature and recent clinical studies on changes in plasma cortisol hormone concentrations in cognitive impairment in Parkinson's disease. The article presents the reasons for the relationship between cognitive impairment in Parkinson's disease, in particular vascular Parkinsonism and neurodegenerative diseases, as well as the results of neuropsychological tests. Methods: We studied the level of morning plasma cortisol in 68 patients with Vascular Parkinsonism (VP) who were hospitalized in 1 st neurology department of TMA in the period from 2015 to the present.The relationship between increased morning plasma cortisol and cognitive impairment was determined.The results of the study were statistically analyzed.Cortisol was determined in all blood samples of patients of the Main and Control groups.The control group consisted of 47 volunteers. Results: Normal levels of cortisol were observed in 20 patients (29%) with vascular parkinsonism,, moderate increases in cortisol were observed in 37 patients (54.4%), and elevations in cortisol were observed in 11 patients (16.1%). Was determined the relationship between the value of cortisol and the assessment of cognitive impairment.In the main group, a statistically significant moderate inverse correlation was determined between plasma cortisol level and cognitive impairment in VP. When studying cortisol levels in VP, its significant increase is noted than in the control (p <0.05). Conclusion: Increased levels of the hormone cortisol in Parkinson's disease play an important role in cognitive impairment and during the course of the disease and affect the effectiveness of VP therapy.