Reduced gut microbial diversity characterized by decreased Bacteroides is associated with vasovagal syncope in children

Background: Vasovagal syncope (VVS) represents the most prevalent form of orthostatic intolerance in children and is characterized by recurrent fainting episodes that substantially impair quality of life and psychosomatic well-being. The pathogenesis of VVS is primarily associated with dysregulation of the autonomic nervous system. Emerging evidence suggests that the gut microbiota, a complex microbial community residing in the human intestine, plays a pivotal pathological role in various autonomic nervous system related disorders. However, data on the gut microbiota profile in pediatric VVS remain limited. The present study therefore aims to characterize gut microbiota changes in children with VVS and its subtypes, providing novel insights into the underlying mechanisms and potential therapeutic strategies. Method: Fecal samples were obtained from 40 children diagnosed with VVS, comprising 20 with the vasodepressor subtype, 8 with the cardioinhibitory subtype, and 12 with the mixed subtype, as well as from 60 age-matched healthy controls. Microbial community composition was assessed through 16S rRNA gene sequencing. Alpha and beta diversity analyses were conducted to evaluate differences between the VVS and HC groups, as well as among the different VVS subtypes. Then, the bacterial flora with significant differences was identified based on microbial relative abundance data using the Wilcoxon rank-sum test, ANCOM-BC2, and LEfSe analyses. Results: . No significant differences in alpha or beta diversity indices were observed among the VVS subtypes including vasodepressor, cardioinhibitory, and mixed types. Conclusion: , may be involved in the development of VVS.