Weird Brain-Body Link Connects Head Injuries With Deadly Gut Infections

A mouse on a football field during a Ravens vs. Panthers game in 2002. Craig Jones/Getty

Traumatic brain injury affects an estimated 1.7 million people in the U.S. every year, and has gained publicity due to the high numbers of football players and ex-football players included in that number. As scientists learn more about TBI, a strange facet of the condition has been found in mice: researchers from the University of Maryland School of Medicine found an association between traumatic brain injury and clear changes in the gut in a study published in November in Brain, Behavior, and Immunity .

According to Science Alert after a traumatic brain injury, people experience GI symptoms, and may be at increased risk for sepsis. In groups of mice given traumatic brain injuries, the researchers found changes in the colon that paralleled these symptoms.

Using mice, they recreated this effect by giving them brain injuries and monitoring their colons a day, then a month after the fact. Compared to mice who hadn't been so whacked, the researchers found that the injured mice had significantly thicker mucosal tissue and smooth muscle tissue. The colons of the injured mice were also much more permeable to fluids.

Football player Drew Brees with Mickey Mouse at Disney World in Florida. Getty

Going a step further, the researchers infected the injured mice with a microbe called Citrobacter rodentium. They found increased inflammation and injury in the brains of the injured mice given that bacteria. They take this to mean that, when it comes to brain injury, there's a two way-street between the gut and the head. Each, the researchers say, affects the other.

This isn't the first time that scientists have examined the connection between the injured brain and the gut. In 2016, researchers found that changes in the gut flora due to antibiotics may prevent against brain damage after a stroke. They found that transferring microbes from mice who were given antibiotics to mice who weren't also helped guard the brain after stroke.

It's of course important to remember that there's a long way to go between mice and men. Translating results between the two is tricky business. An effect you see in one doesn't always translate to the other, although it's unlikely, for obvious reasons, that researchers will ever try this on human beings. But future clinical research in living humans can one day help paint a fuller picture.