The Gut Microbiome as a Modulator of Traumatic Brain Injury Pathology and Symptoms

Traumatic brain injuries (TBIs) affect millions annually, leading to devastating neurobehavioral consequences and increasing risk for neurodegenerative and psychiatric diseases. However, therapies are lacking. Starting in 2018, dysbiosis of the gut microbiome was identified as an acute, and potentially chronic, pathology originating from TBI. Recent studies established that the microbiome contributes to the evolution of TBI pathology and functional impairments. The gut microbiome is the collection of microorganisms that inhabit the stomach through colon and is indicated as a contributor to myriad neurological and psychiatric conditions. This makes it an intriguing target to understand in the context of TBI. Thus, this review focuses on the evidence establishing the gut as a modulator of TBI and the major potential mechanisms by which this occurs. This includes regulation of food processing into host-usable nutrients, inflammatory signaling, and vagus nerve modulation. Each of these areas provides potential for future therapeutic development and intervention but there are also multiple areas where microbiome-TBI science could be improved.