The microbiome of patients with social anxiety disorder is altered in comparison to healthy controls. The Gut Microbiome in Social Anxiety Disorder; Evidence of Altered Composition and Function

The microbiome-gut-brain axis plays a role in anxiety, the stress response and social development, and is of growing interest in neuropsychiatric conditions. The gut microbiome shows compositional alterations in a variety of psychiatric disorders including depression, generalised anxiety disorder (GAD), autism spectrum disorder (ASD) and schizophrenia but studies investigating the gut microbiome in social anxiety disorder (SAD) are very limited. Using whole-genome shotgun analysis of 49 faecal samples (31 cases and 18 sex- and age-matched controls), we analysed compositional and functional differences in the gut microbiome of patients with SAD in comparison to healthy controls. Overall microbiome composition, as measured by beta-diversity, was found to be different between the SAD and control groups and several taxonomic differences were seen at a genus- and species-level. The relative abundance of the genera Anaeromassillibacillus and Gordonibacter were elevated in SAD, while Parasuterella was enriched in healthy controls. At a species-level, Anaeromassilibacillus sp An250 was found to be more abundant in SAD patients while Parasutterella excrementihominis was higher in controls. No differences were seen in alpha diversity. In relation to functional differences, the gut metabolic module ‘aspartate degradation I’ was elevated in SAD patients. In conclusion, the gut microbiome of patients with SAD differs in composition and function to that of healthy controls. Larger, longitudinal studies are warranted to validate these preliminary results and explore the clinical implications of these microbiome changes.

微生物群-肠-脑轴（microbiome-gut-brain axis）在焦虑、应激反应及社会发育过程中发挥调控作用，目前在神经精神疾病领域受到越来越多的关注。肠道微生物群的组成在多种精神疾病中存在异常，包括抑郁症、广泛性焦虑障碍（GAD）、孤独症谱系障碍（ASD）及精神分裂症，但针对社交焦虑障碍（SAD）患者肠道微生物群的相关研究仍十分有限。本研究对49份粪便样本（31例SAD患者与18例性别年龄匹配的健康对照）进行全基因组鸟枪法测序（whole-genome shotgun analysis）分析，对比了SAD患者与健康对照的肠道微生物群组成与功能差异。通过贝塔多样性（beta-diversity）分析发现，SAD组与对照组的整体微生物群组成存在显著差异，且在属和种水平上均观察到多项分类学差异。SAD患者体内厌氧马赛杆菌属（Anaeromassillibacillus）与戈登杆菌属（Gordonibacter）的相对丰度显著升高，而健康对照中副萨特氏菌属（Parasuterella）的丰度更高。在种水平上，SAD患者体内厌氧马赛杆菌属菌种An250（Anaeromassilibacillus sp An250）的相对丰度更高，而健康对照中粪便副萨特氏菌（Parasutterella excrementihominis）的丰度显著提升。阿尔法多样性（alpha-diversity）未观察到显著差异。在功能差异方面，SAD患者的肠道代谢模块‘天冬氨酸降解I（aspartate degradation I）’丰度显著升高。综上，SAD患者的肠道微生物群在组成与功能上均与健康对照存在差异。未来需开展更大样本量的纵向研究以验证本初步结论，并探索这些微生物群改变的临床意义。