As many as 3.8 million people sustain sports- and recreation-related concussions each year in the US, but diagnoses of these brain injuries remain challenging. In a study published this week in the British Journal of Sports Medicine, researchers describe a saliva-based test that accurately detected concussions in male rugby players.
“What’s exciting about this is we not only found a very accurate way of identifying brain trauma, but also we found it in saliva, which is not invasive,” Antonio Belli, a trauma neurosurgery researcher at the University of Birmingham in the UK and a coauthor of the study, tells The Washington Post. “Everybody, including myself, has been looking at blood for many years. We’ve never really seen anything so exciting for mild traumatic brain injury.”
The test measures expression levels of 14 small noncoding RNAs in saliva, including microRNAs. “MicroRNAs are messages the cells transmit in response to an event, like a brain injury,” Belli tells The Guardian. “The place where you find microRNAs most abundantly is saliva. Salivary glands are connected directly to the brain by nerves. We’re seeing this response within minutes of injury.”
The researchers compared saliva samples in male rugby players that experienced head injuries, uninjured players, and those with injuries to another part of the body. More than 1,000 people participated in the study. On the basis of these RNA saliva biomarkers, they detected concussions with 94 percent accuracy, the Post reports.
Concussion diagnoses are often made based on symptoms such as behavior or, in hospital settings, with brain imaging. “The diagnosis of concussions is really based on clinical findings. A lot of that is based on what a person reports,” William Barr, the director of neuropsychology at New York University who wasn’t involved with the research, tells the Post. “What we’ve always been looking for is: Is there something objective? Because, in a lot of cases, they’ll deny [feeling symptoms]. That’s what this really adds.”
The saliva-based test described in the study relies on PCR and must be sent to a lab for analysis. But, according to The Guardian, the researchers are in the process of developing an over-the-counter version that could provide instant results to injured athletes, victims of traffic accidents, soldiers, and others who experience head injuries.
There is currently an FDA-approved blood test for concussion that measures the abundance of two proteins. Penn State researchers have also developed a test that measures saliva noncoding RNAs as biomarkers of concussion. According to Fox43, these researchers are also planning to develop a handheld tool that could deliver results within 30 minutes.
Notably, the UK-based study only tested male rugby players. Research suggests that there are gender- and sex-related differences in concussions, meaning that further study would be needed before the test could be applied to women.