Author contribution: Fokin VF performed data analysis and wrote the manuscript; Shabalina AA performed biochemical analysis of cytokines and participated in writing the manuscript; Ponomareva NV collected and analyzed psychometric data, participated in writing the manuscript; Medvedev RB performed clinical examinations, analyzed the literature and proposed the study design; Lagoda OV analyzed clinical data and proposed the study design; Tanashyan MM proposed the study design, summarized clinical data in the context of the obtained results.

Compliance with ethical standards: the study was approved by the Ethics Committee of the Research Center of Neurology (Protocol No. 11/14 dated November 19, 2014); all study participants signed informed consent to participate.