A non-invasive saliva test could diagnose concussions among rugby players, research suggests.
The athletes are prone to the temporary head injury, which can occur following a bump, blow or jolt.
Concussions usually cause a fleeting headache, slight dizziness and nausea, however, they can be a medical emergency that leads to lasting problems.
Rugby players are no stranger to concussions, however, cases may be missed in amateur games where medics are not on hand.
To learn more, scientists from the University of Birmingham analysed the saliva of over 1,000 professional male players before the season.
Some also provided samples during a game, immediately afterwards and up to two days later.
These samples were compared against those of 102 uninjured players and 66 with just muscle or joint difficulties.
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Results reveal the players with a concussion had distinct chemical signatures in their saliva.
Saliva is thought to receive signals from the cranial nerves in the mouth and throat, allowing medics to rapidly register a traumatic brain injury.
A patented salivary test is being commercialised for elite male athletes, according to the scientists.
Mild head injuries usually heal at home, however, patients should be taken to A&E if they are unconscious, repeatedly vomit, have a persistent headache, endure memory loss or experience a change in behaviour.
Failing to treat serious concussion can cause persistent symptoms or even life-threatening brain swelling in rare cases.
With no specific test, medics usually assess a patient for signs of a head injury.
Genetic sequencing has revealed specific molecules called small non-coding RNAs (sncRNAs) regulate the expression of different proteins that are linked to diseases like Alzheimer's and cancer.
To uncover whether sncRNAs could indicate a concussion, the Birmingham scientists analysed more than 1,000 male rugby players in the top two tiers of England's union across the 2017 to 2019 seasons.
All the participants provided saliva samples before the season began.
One hundred and fifty-six also gave samples while having a "gold standard" head injury assessment, carried out during a game, immediately afterwards and 36 to 48 hours later.
Fourteen sncRNAs were discovered in the saliva of concussed players, but not the individuals with a suspected traumatic brain injury where concussion had been ruled out.
These 14 sncRNAs were also absent in the uninjured players and those with just muscle or joint issues.
The molecules were present in the saliva immediately after the game and 36 to 48 hours later.
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The scientists stressed looking for sncRNA in saliva cannot replace gold-standard head injury assessments, but could help gauge a patient's condition on the pitch.
"Concussion can be hard to diagnose and is often missed, especially where a structured evaluation by an expert clinician is not possible, for example, at grass-root level," they wrote in the British Journal of Sports Medicine.
"Small non-coding RNAs can provide a diagnostic tool that might reduce the risk of missing this type of injury at all levels of participation."
With concussions being relatively poorly understood, sncRNAs may help shed light on how the injury evolves over time.
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"The detection of signatures of concussion at early time points in saliva (a non-invasively sampled biofluid) presents both at the pitch side, and in primary care and emergency medicine departments, an opportunity to develop a new and objective diagnostic tool for this common clinical presentation," wrote the scientists.
While a patented test is commercialised, the team "aims to collect further samples from players in two elite men's rugby competitions to provide additional data to expand the test and develop its use".
"This will guide the prognosis and safe return to play after concussion and further establish how the test will work alongside the head injury assessment process," wrote the scientists.
"We are also carrying out several additional studies to further validate and expand the test for use in different groups that were not included in the present SCRUM study, including female athletes, young athletes, and community sports players."
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