Can concussion clues come from the gut?

Indicators of concussion could be found in the gut, giving new levels of insight into its impact and when it may be safe to return to action, new research has revealed. 

By taking blood, stool and saliva samples, a new study was able to examine the diagnostic potential of the gut’s microbiome.

The research, conducted with 33 Rice University footballer players over the course of one season, found a post-concussion drop-off of two bacterial species normally found in abundance in stool samples of healthy individuals.

It also found a correlation between traumatic brain injury linked proteins in the blood and one brain injury linked bacterial species in the stool.

After a concussion, the injuries cause inflammation, sending small proteins and molecules circulating through the blood that breach the intestinal barrier and cause changes in the gut, affecting metabolism.

The Houston Methodist research said these changes in the microbiota can deliver vital clues to help safeguard the person and their recovery. 

“Until your gut microbiome has returned to normal, you haven’t recovered,” said Dr Sonia Villapol, assistant professor of neurosurgery at the Center for Neuroregeneration in the Houston Methodist Research Institute. 

“This is why studying the gut is so useful. It doesn’t lie. And that is why there is so much interest in using it for diagnostic purposes.”

While brain movement within the skull may cause injury to nerve cells, such microscopic cellular injuries are not visible on imaging tests like X-rays, CT scans and MRIs, which are more capable of finding injuries on the scale of skull fractures, brain bleeding or swelling. 

As a result, the most commonly used test for diagnoses of concussions relies on self-reported symptoms like blurry vision, dizziness, nausea and headaches, which can be very vague, subjective and often underreported by athletes who want to continue playing. This can make them notoriously difficult to diagnose.

While there have been dozens of brain injury biomarkers identified, there has been limited success in developing commercial blood tests sensitive enough to detect tiny increases in biomarker concentrations, although a saliva test has been found to be effective.

However, due to the fact the central nervous system is intimately linked to the enteric nervous system, this could provide new insight, Dr Villapol said.

While only four of the players in the study were diagnosed with major concussions, the researchers say the results will need to be confirmed in a larger sample size. 

They also plan to conduct a similar study soon among women in sport, who similarly have frequent head trauma.

“Women and men don’t have the same immunities or gut microbiomes, and as a woman and a mother of daughters, I would hate to be that researcher who only looks at men’s issues while overlooking women,” Dr Villapol said.

“Women soccer players have very high rates of concussions, as well, and all the same problems when it comes to existing diagnostic methods.”