[Development of early diagnosis of Parkinson's disease based on the search for biomarkers such as premotor symptoms and changes in blood].

OBJECTIVE To determine changes in the chemical composition of blood plasma in subjects at risk of Parkinson's disease (PD) at the prodromal stage compared with age control. MATERIAL AND METHODS Subjects at risk were selected for the presence of characteristic premotor symptoms, including impairments of sleep, olfaction and constipation.The risk group included 12 people, the control group - 8 people. RESULTS Among seven catecholamines and their metabolites detected in the blood, only the concentration of L-dioxiphenylalanine (L-DOPA) changed (decreased) in subjects at risk compared with the control. A decrease in the concentration of L-DOPA is considered as a manifestation (marker) of selective degeneration of central and peripheral catecholaminergic neurons in PD. In contrast to L-DOPA, the concentration of seven of the twelve detected sphingomyelins in the blood of the subjects at risk increased. Given that a change in the metabolism of sphingomyelins is associated with processes such as apoptosis, autophagy, and synucleinopathy, an increase in their concentration in the blood of patients at risk is considered as a manifestation of systemic general degeneration of central and peripheral neurons. Finally, in the blood of subjects at risk, we found a trend towards a decrease in the concentration of urates, which are endogenous neuroprotectors. CONCLUSION The changes in the level of L-DOPA, sphingmyelins and urates in the blood of subjects at risk may serve as diagnostic markers of PD at the prodromal stage.