Gut Instinct: How the Microbiome Affects Traumatic Brain Injury, A Narrative Review

Objectives: Emerging evidence suggests that the gut microbiome may play a role in the pathophysiology of traumatic brain injury (TBI). The objective of this systematic review is to identify and evaluate studies that investigate the relationship between TBI and gut microbiota alterations. Methods: Using the PRISMA 2020 Checklist, we searched five databases to identify relevant studies. Two independent researchers screened titles and abstracts and identified eligible studies according to the following PICO: studies that investigated the relationship between TBI and gut microbiota AND reported outcomes related to gut microbiome alterations. We assessed the risk of bias for included studies, extracted methodological data and related results of the articles, and used them for qualitative analysis. Results: We screened the titles and abstracts of 23 identified records and assessed the full text of 10 studies. In total, 5 studies met eligibility criteria and were entered into the qualitative analysis. These studies investigated the effects of TBI on gut microbiota in animal models and human patients. Although, we planned to systematic review, lack of adequate quantitively and qualitative data compelled us to write a narrative survey. The majority of studies reported significant alterations in gut microbiota composition and function following TBI, with potential implications for immune function, inflammation, and neurological recovery. Conclusion: This systematic review provides evidence supporting a relationship between TBI and alterations in gut microbiota. While the exact mechanisms underlying this relationship remain unclear, these findings suggest that targeting the gut microbiome may represent a novel therapeutic approach for TBI. Further studies are needed to elucidate the mechanisms involved and to evaluate the potential benefits of gut microbiota-targeted interventions in TBI.