Laboratory Saliva Test Detects Concussion Signs in Elite Rugby Players

New study boosts the promise of one day being able to diagnose concussions quickly and easily on the sidelines.
Rugby players in white shorts and either blue or red shirts push against each other during a match.
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Chris Gorski, Editor

(Inside Science) -- A study of elite male rugby players in England indicates that RNA in their saliva can signal that a player has experienced a concussion. The test takes about 24 hours to process in a laboratory, so it isn't ready for the sideline. However, the new research takes a substantial step toward showing that information present in saliva could eventually be used to diagnose concussions in athletics and other settings.

Antonio Belli, a neurosurgeon at the University of Birmingham in the U.K., said during a press conference that the test "provides an invaluable tool to help clinicians diagnose concussion more consistently and accurately." He added that the test could be used not only in sports, from amateur to professional levels, but also in health care and military settings. These biomarkers may pave the way for an eventual diagnostic test that is comparable in accuracy to exams provided by medical professionals. This could be especially beneficial to athletes in community sports who often don't have easy access to the kind of medical evaluation offered to professionals.

The new test, which uses an algorithm to analyze a set of 14 biomarkers found in saliva, would add an objective data point to an assessment by a medical provider. The researchers found that the results from the test matched the diagnosis of a medical expert more than 90% of the time.

The study, published this week in the British Journal of Sports Medicine, examined saliva tests from more than 1,000 male high-level rugby players, most of whom are white. The researchers envision that future efforts will study how well the test works with male and female athletes in other sports, as well as people of other ages and ethnicities. The test uses snippets of RNA known as small non-coding RNAs, which can be detected using the same polymerease chain reaction technique that quickly makes copies of DNA and RNA to help scientists study them and is used in COVID-19 tests.

The research trial included players with diagnosed concussions, players who had suffered head impacts but been cleared of concussions after an exam, players with musculoskeletal injuries, and healthy players.

Other researchers who were not involved in the study praised its approach. "They're comparing their concussion group against a group of athletes who underwent a head injury [exam] because they were observed to have head contact or head impact on the field, but then subsequently were not diagnosed with a concussion," said Steve Hicks, a pediatrician at the Penn State College of Medicine, in Hershey. That's important, he said, because researchers in the field are trying to identify molecules that indicate when a concussion has occurred.

Belli said the molecules the tests detect may be released when salivary glands respond quickly to injuries, sending out micro-RNAs to let other cells know what genes are needed to respond to the injury.

The researchers collected saliva samples during and after games, and also 36-48 hours after the end of games. Testing the samples takes about 24 hours currently, although Belli is optimistic that results can be assessed much more quickly. "Currently this is a lab test," said Belli. The next big step, he said, is finding a way to make the technique both portable and more rapid.

Additionally, Hicks noted that to have a truly rapid test able to help determine if a player should return to play during a game, technological advances are needed. "But there are certainly bioengineers out there working on this problem. And I think that there are probably devices that will be available in the next two to three years to make those kind of measurements."

"This is a very important step forward because it gives you another tool in the toolbox to diagnose concussions," said Douglas Smith, a neurosurgeon at the Perelman School of Medicine at the University of Pennsylvania, in Philadelphia, who was not involved with the research.

The researchers wrote in the paper that the test may eventually be used in various amateur sports settings where "access to a trained healthcare professional is limited both during and after the game."

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Chris Gorski is the Senior Editor of Inside Science. Follow him on twitter at @c_gorski.