The repeat head injuries suffered by football players, boxers and other athletes appear to affect brain health long after players have given up their sport.
New research from Johns Hopkins University in Baltimore could explain why: The persistence in the brain of inflammation tied to the original injury or injuries.
"The findings show that participating in repeated collision sports like football may have a direct link to long-term inflammation in the brain,"study senior author Dr. Jennifer Coughlin said in a university news release.
She's an associate professor of psychiatry and behavioral sciences at Hopkins.
Key to the new findings is a brain "repair protein," with the unwieldy name of 18 kDa translocator protein -- shortened to TSPO.
Whenever a brain sustains injury, TSPO levels quickly rise as the brain tries to heal. TSPO is closely associated with immune cells in the brain called microglia, Coughlin's group noted.
It was thought that spikes in TSPO were only temporary. However, prior studies revealed that levels of the pro-inflammatory protein can remain elevated for up to 17 years.
In the new study, the Hopkins team examined PET and MRI brain scans of 27 former NFL players, taken between 2018 and early 2023.
They used the scans to compare levels of TSPO in the football players' brains to those seen in brain scans of 27 former pro college swimmers -- athletes who would not be expected to have sustained head injuries.
The swimmers and the football players were all male and ranged between 24 and 45 years of age.
Brain levels of TSPO were higher, on average, in scans taken from the football players versus those from the swimmers.
Football players also performed notably worse than swimmers on tests that tracked learning and memory skills.
"These findings are relevant to both collision sport athletes and other populations that suffer from single or reoccurring mild TBIs, including those experienced during military training and repeated head-banging behaviors in children,"Coughlin said in a Hopkins news release.
Should treatments to lower brain TSPO be given to older individuals with a history of head injury? Probably not, the researchers cautioned.
"Since TSPO is associated with [brain] repair, we don't recommend the use of drugs or other interventions at this time," Coughlin explained. "Instead, we will continue to monitor TSPO levels through more research, in order to test for sign of resolution of the injury with more time away from the game."
Following more research, it might be possible to find treatments that can safely reduce long-term inflammation in the brain, the researchers said.
With that in mind, Coughlin's group plans to track TSPO levels in the brains of former NFL athletes over time, seeing which brains heal and which do not. That could give clues to new treatments or guidelines that would encourage long-term healing.
The findings were published recently in the journal JAMA Network Open.
More information
There's more on the health impact of sports-related concussion at the University of Michigan.
SOURCE: Johns Hopkins University, news release, Nov. 29, 2023
