Background. Autism spectrum disorders (ASD) in children are associated with features of neuropsychological development, characterized by socio-communicative, emotional, and behavioral problems. The processes of interaction between the central and enteric nervous systems, taking into account the inherent RAS reactions of autonomic maladaptation, endogenous stress, eating behavior determine the pathophysiological mechanisms underlying the comorbid pathology of the digestive system. The study was aimed to analyze the cerebral intestinal interaction signs in children with ASD, taking into account the role of NSE and S-100 neurotransmitters. Materials and methods. Sixty-six children with ASD were examined, out of which 45 children had concomitant functional disorders of the digestive system (FDDS). Clinical manifestations of ASD were assessed by the CARS scale; FDDS was diagnosed based on the Rome IV criteria. Serum levels of NSE neurotransmitters and S-100 protein were measured immunochemically. The patients were examined after obtaining informed consent in compliance with the principles of bioethics. Results. According to the data obtained in children with ASD, the frequency of concomitant FDDS is 68.20 %. In this case, ASD in combination with functional disorders of the biliary tract (FDBT) is observed in 22.7 %, with irritable bowel syndrome (IBS) — in 27.30 %, with syntropic FDDS — in 18.20 % of patients. The study traced the association between severe ASD and concomitant FDDS, in particular ASD with isolated IBS (p = 0.004), ASD with isolated FDBT (p = 0.009), ASD with syntropic functional disorders (p = 0.041). Increased serum concentrations of the NSE and S-100 neurotransmitters have been observed in children with concomitant FDDS. The level of S-100 protein and clinical manifestations of FDDS reveal a correlation, the degree of which increases in the following sequence: IBS (r = 0.34), and syntropic FDDS (r = 0.48). Conclusions. Peculiarities of cerebral intestinal interactions in ASD determine the high frequency of FDDS, in the structure of which IBS dominated. The presence of concomitant pathology impacts the clinical manifestations of ASD, complicating its course to a greater extent in cases of syntropic FDDS. Involvement of enteric glial structures in ASD is accompanied by the NSE and S-100 neurotransmitters level increase on the background of concomitant FDDS. The diagnostic value of S-100 protein in IBS in children with ASD is shown.
