Gut Microbiome Differentiates Levels of Consciousness in Patients with Prolonged Disorders of Consciousness after Brain Injury

Differentiation of levels of consciousness in patients with prolonged disorders of consciousness (DOC) remains a major challenge, especially differentiation between vegetative state (VS) and minimally conscious state (MCS). This study was to investigate the alterations of gut microbiota in patients with DOC and to identify potential microbiome biomarkers that can differentiate levels of consciousness. In this study, we collected fecal samples from patients with prolonged DOC, including 19 patients in MCS and 14 patients in VS; 16S-rRNA sequencing was used to investigate the gut microbiome of patients. Gut microbiota diversity, composition, and discriminant bacterial taxa were analyzed to identify potential biomarkers for differentiating levels of consciousness. We found that diversity and composition of gut microbiome were significantly altered in patients with DOC, and decreased alpha diversity was associated with lower levels of consciousness. Specific bacterial taxa including Firmicutes, Escherichia_shigella, Raecalibacterium, Lachnospiraceae, and Ruminococcaceae_UCG_013 were more abundant in patients in MCS, whereas Clostridiales were more abundant in patients in VS. In conclusion, the study results demonstrated that patients with DOC exhibited distinct diversity and composition of gut microbiota. And there was a decreasing trend of alpha diversity of gut microbiota from patients in MCS to patients in VS, which indicates that lower alpha diversity was associated with more severe level of unconsciousness. Specific bacterial taxa may be potential biomarkers to differentiate MCS and VS.