Gut microbiota and central nervous system: a bidirectional two-sample Mendelian randomized analysis

Abstract Background Previous studies have shown that alterations in the gut microbiota are associated with the progression of central nervous system(CNS)disorders. Whether this connection reflects a causal relationship still unclear. We aimed to reveal a causal relationship between the gut microbiota and CNS diseases such as anoxic brain injury (ABI) and bacterial meningitis (BM). Methods A two-sample bi-directional Mendelian randomization (MR) analysis was performed by using genetic variants from genome-wide association studies as instruments variables for gut microbiota, ABI and BM. This study used inverse variance weighted, weighted median, MR-Egger and weighted mode methods to evaluate the causal relationship among gut microbiota, ABI and BM. Sensitivity analyses including horizontal pleiotropy analysis, Cochran's Q test, and leave-one-out method were subsequently performed to assess the reliability of the results. Results We found that the increased abundance of Lachnospiraceae family and Butyricoccus genus was positively associated with the risk of ABI. The increased abundance of Lactococcus, Ruminococcus gauvreauii and Desulfovibrionales genera were positively associated with the risk of BM, while Eubacterium ventriosum genus, Erysipelatoclostridium genus and NB1n order were negatively associated with the risk of BM. On the other hand, CNS disorders altered the composition of the gut microbiota. Conclusion MR analysis have shown a bidirectional causal relationship between the abundance of specific bacteria and ABI and BM, providing evidence for gut microecological therapies for ABI and BM.