Gut Microbiome: A Potential Indicator for Differential Diagnosis of Major Depressive Disorder and General Anxiety Disorder.

Major depressive disorder (MDD) and general anxiety disorder (GAD) share many common features, leading to numerous challenges in their differential diagnosis. Given the importance of the microbiota-gut-brain axis, we investigated the differences in gut microbiota between representative cases of these two diseases and sought to develop a microbiome-based approach for their differential diagnosis. We enrolled 23 patients with MDD, 21 with GAD, and 10 healthy subjects (healthy crowd, HC) in the present study. We used 16S rRNA gene-sequencing analysis to determine the microbial compositions of the gut microbiome based on Illumina Miseq and according to the standard protocol. GAD showed a significant difference in microbiota richness and diversity as compared with HC. Additionally, Otu24167, Otu19140, and Otu19751 were significantly decreased in MDD relative to HC, and Otu2581 and Otu10585 were significantly increased in GAD relative to MDD. At the genus level, the abundances of and were significantly lower in MDD relative to HC, and the abundances of and _R7_group were significantly lower in GAD than in HC. The abundance of was significantly higher whereas that of was significantly lower in GAD relative to MDD. Moreover, we observed that _R7_group negatively correlated with the factor score (Limited to Hopelessness) and total score of HAMD-24 ( < 0.05), whereas negatively correlated with FT4 ( < 0.05). Furthermore, the GAD group showed significant differences at the genus level for , which negatively correlated with PTC ( < 0.05). This study elucidated a unique gut-microbiome signature associated with MDD and GAD that could facilitate differential diagnosis and targeted therapy.