The inherent difficulties in correctly diagnosing a concussion have led scientists to look far and wide for biomarkers that clearly reveal the extent of a brain injury. For researchers at the Methodist Research Institute in Houston, this search led them to gut bacterial communities, where they found that post-concussion changes could be used to detect the state of recovery.
When severe blows to the head, such as skull fractures or brain swelling, can occur through X-rays or CT scans, microscopic injuries that damage nerve cells can be so subtle that they go undetected. The subject’s self-report of things like dizziness, blurred vision, or nausea is therefore the primary diagnostic technique for on-site medical experts, but the risk of misreporting and secondary brain injury is very real among competitive athletes with aversion to bench press.
The idea that concussion can create specific biomarkers that can be used for timely and definitive diagnosis is therefore attractive, with a number of research teams breaking into this space. Blood tests are an area where we are seeing a lot of activity, with the FDA even approving the first such test in 2018, which tracks two proteins that appear in the blood after a brain injury. Saliva and urine testing are other techniques that show potential.
Recently, scientists have also begun to study the potential of our intestinal bacteria to detect signs of brain damage, and studies on animal models and cell cultures show provide promising signs. The Houston Methodist team further investigated this by tracking 33 college football players over the course of the season, collecting blood, feces and saliva samples at three intervals along the way to build a picture of their gut microbiome.
Following concussions, the team found a reduction in the levels of two types of bacteria that are commonly found in abundance in healthy individuals. They also found correlations between proteins associated with traumatic brain injury in the blood and bacteria associated with brain injury in the stool. They may be the result of inflammation caused by a concussion that alters the proteins and molecules circulating in the body, disrupting the intestinal barrier and transforming intestinal bacteria and metabolism.
Together, these results offer early evidence that “detecting changes in the intestinal microbiome may help improve the diagnosis of concussion after a head injury,” the researchers wrote in their paper. Much more work is needed, including studies with larger sample sizes, but these types of biomarkers can also one day be used not only to confirm a concussion, but also to assess how well the patient is recovering from the injury, according to the author. of the study Sonia Vilapol.
“Until your gut microbiome returns to normal, you have not recovered,” she said. “That’s why studying the gut is so useful. It doesn’t lie. And that’s why there’s so much interest in using it for diagnostic purposes.”
The study was published in the journal Brain, behavior and immunity – health.