Аннотация:Parkinson’s disease (PD) is diagnosed many years after its onset, under a significantdegradation of the nigrostriatal dopaminergic system, responsible for the regulation of motor function.This explains the low effectiveness of the treatment of patients. Therefore, one of the highest prioritiesin neurology is the development of the early (preclinical) diagnosis of PD. The aim of this studywas to search for changes in the blood of patients at risk of developing PD, which are consideredpotential diagnostic biomarkers. Out of 1835 patients, 26 patients were included in the risk group and20 patients in the control group. The primary criteria for inclusion in a risk group were the impairmentof sleep behavior disorder and sense of smell, and the secondary criteria were neurological andmental disorders. In patients at risk and in controls, the composition of plasma and the expression ofgenes of interest in lymphocytes were assessed by 27 indicators. The main changes that we foundin plasma include a decrease in the concentrations of l-3,4-dihydroxyphenylalanine (L-DOPA) andurates, as well as the expressions of some types of microRNA, and an increase in the total oxidativestatus. In turn, in the lymphocytes of patients at risk, an increase in the expression of the DA D3receptor gene and the lymphocyte activation gene 3 (LAG3), as well as a decrease in the expression ofthe Protein deglycase DJ-1 gene (PARK7), were observed. The blood changes we found in patients atrisk are considered candidates for diagnostic biomarkers at the prodromal stage of PD.