The key to definitively diagnosing a concussion could be in a player’s mouth.

That’s the theory researchers at the University of Birmingham plan to test this upcoming rugby season when they partner with the British sport’s governing body and the country’s two top leagues to collect samples of players’ saliva before and after a suspected head injury.

“The University of Birmingham recently made a significant breakthrough after identifying molecules, which can be found in saliva and act as biomarkers to indicate whether the brain has suffered injury,” Prof. Tony Belli said in a news release about the upcoming study, which was first reported by the BBC.

The molecules, called microRNA, used to be thought of as genetic waste, Belli told The Washington Post on Wednesday. But in recent years, researchers discovered these biomarkers can be used as a diagnostic tool to detect certain types of cancer and other ailments. Now, Belli is hoping to prove certain microRNA found in a person’s saliva can diagnose a traumatic head injury.

“What we have discovered here … is that within minutes of an injury the body starts releasing fragments of genetic material that can be used to, first of all, diagnose a concussion but also to monitor the concussion over time until the player is ready to return to play,” Belli said.

The study will run throughout the 2017-18 season and test players in the Aviva Premiership and Greene King IPA Championship leagues. Samples will first be collected from all players ahead of games to serve as a baseline. Then during games, if a player suffers a suspected head injury, he will be removed as he normally would be and required to give a small sample of saliva, which will be sent to Birmingham’s lab for analysis.

Players who did not suffer a suspected head injury will also give samples after the game so researchers can compare to those of injured players to others to further assess the reliability of these biomarkers.

“If these biomarkers are found reliable, we can continue our work with industrial partners with the hope to have a device available within the next two years that will instantaneously diagnose concussion on the pitch-side with the same accuracy as in the laboratory — a major step forward for both sport and medicine,” Belli said.

Belli added that he envisions a tool that won’t just be used in pro sports, but for amateurs, as well, including for youth players.

“In the U.K., most matches are below the top tiers,” he said. “There isn’t a doctor there; there’s usually parents, so what we’re really hoping is that you have an objective test that can be used by anyone with minimal training.”

Physicians who specialize in concussions, however, warn any diagnostic tool — either in the laboratory of the sideline — likely won’t be adequate to replace a clinical diagnosis, especially when used by a nonmedical professional.

“I think these biomarkers have a good value to say some type of injury has occurred in the brain, but what it won’t tell you is how it correlates with [a player’s] function at the time,” said Marilyn Kraus, director of George Washington University’s Traumatic Injury Program and Concussion Clinic. The GW program diagnoses concussions based on a variety of factors, including individualized exercises that test things like cognition and balance, as well as through the use of brain scans and other clinical tools.

Referring to growing concern over the long-term effects of concussions, Kraus said if anyone, especially a child, gets injured, he or she should be pulled from the game immediately and held out, regardless of what a diagnostic test might suggest.

“The pendulum is never going to swing the other way,” she said. “All these evaluation tools are going to be great, but they will never replace [a clinical diagnosis], at least in my lifetime.”

English rugby’s governing body, Rugby Football Union, is optimistic that Belli’s research may at least help make its head injury protocols safer.

“There is currently no reliable or proven biomarker or objective test for the diagnosis of concussion and this lack of objectivity is the biggest challenge facing medical professional in dealing with this type of injury,” RFU Chief Medical Officer Dr. Simon Kemp said in a statement. “While very much an exploratory piece of research, this is a project that has the potential to make a very significant impact on the diagnosis and management of players following concussion.”

Concussions in rugby are presently diagnosed using the 10-minute Head Injury Assessment protocol, as mandated by World Rugby. However, the protocol has been criticized because it is based almost entirely on subjective data.

“Brain-damaged players are routinely being allowed to return to the field week after week,” critic Dr. Barry O’Driscoll told the Daily Mail last year following the controversial handling of Northampton’s George North. North was allowed keep playing after appearing to lose consciousness following a hard hit.

“They have no clinical right to say this HIA test has any credibility at all,” added O’Driscoll, who retired from World Rugby’s medical committee in 2012 because of objections to the protocol. “Player after player after player is going back on after damaging their brains.”

Premiership Rugby Head of Elite Performance and Player Development Corin Palmer appears to want to avoid such controversies in the future, noting in a statement this week that the University of Birmingham study could help teams make more informed decisions.

“This research has the potential to impact positively on the way in which we assess and manage concussion,” Palmer said. “All Premiership Rugby clubs and players are already taking part in the preparatory stages of the research ahead of the new season, and we look forward to seeing the results of Professor Belli’s work.”

Belli, who has worked as an independent concussion expert for the RFU in the past, said it was easy to get England’s rugby bodies on board.

“Their door was opened,” he said Wednesday, noting the RFU and the rugby leagues have all been “very supportive of this type of research.”

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