Tiny microRNA molecules in saliva may help diagnose and predict the duration of concussions in children, according to a study.
Concussions usually occur after a blow to the head - for example, during sports or a car accident. They can result in such symptoms as headache, nausea, confusion, amnesia or lack of consciousness.
Researchers measured the levels of microRNAs - tiny snippets of non coding RNA - in the saliva of concussion patients.
They found that the presence of certain microRNAs in saliva was able to better identify concussions and more accurately predict the length of concussion symptoms than relying solely on patient surveys.
Steven Hicks from the Pennsylvania State University in the US said the findings, published in the journal JAMA Pediatrics, could result in a more fact-based way to diagnose and treat concussion patients.
"Theres been a big push recently to find more objective markers that a concussion has occurred, instead of relying simply on patient surveys," Hicks said.
"Previous research has focused on proteins, but this approach is limited because proteins have a hard time crossing the blood-brain barrier. Whats novel about this study is we looked at microRNAs instead of proteins, and we decided to look in saliva rather than blood," he said.
While most concussions clear up within two weeks, about one-third of patients will experience symptoms longer.
Patients are usually advised to rest and stay away from such physical activity as sports or gym class until their symptoms subside.
Hicks said that while it is important to give the brain enough time to heal, it is difficult to accurately predict how long patients should rest.
The researchers followed 52 concussion patients between the ages of 7 and 21 for the study.
Each participant was evaluated using the Sport Concussion Assessment Tool (SCAT-3) - a common tool that doctors use to inventory concussion symptoms and severity - within two weeks of their injury.
The researchers also asked the patients parents for their observations about their childrens symptoms.
In the study, they also collected saliva from each participant and analysed for levels of different microRNAs.
They then compared the microRNA profiles to the patients symptoms at both the initial and follow-up assessments.
The researchers isolated five microRNAs that could accurately identify the participants who would experience prolonged symptoms.
These microRNAs could correctly identify if a participant would have prolonged symptoms or not.
"The microRNAs were able to predict whether symptoms would last beyond four weeks with about 85 percent accuracy," Hicks said.
"In comparison, using the SCAT-3 report of symptoms alone is about 64 per cent accurate. If you just go off the parents report of symptoms, it goes down to the mid-50s. In this pilot study, these molecular signatures are outperforming survey tools," he said.
