For anyone who has had to do first aid on someone after they hit their head or make a decision about an athlete’s ability to continue to participate, or if you have had to decide yourself whether or not you may be suffering from a concussion yourself you know how much of a guessing game it can feel like. As a coach, you might experience pressure from parents to make a decision one way or another. And while determining the immediate concussion might seem straight forward (even though it typically is not) when is it safe to return to play?
Even doctors have a tough time with concussions because there are few objective measures. They have to rely primarily on subjective reports from the patient, and potentially their parents or other caregivers or family members. Some sports will do baseline testing so they have something to compare against but there are reports of individuals purposefully underperforming on the base test so that they are less likely to get pulled from their sport should a concussion occur. But if we had something objective to measure then doctors and eventually even coaches might be able to perform a quick test that is significantly harder to argue with from any perspective.
Messenger RNA (mRNA) is they type of RNA that carries the message from DNA in the cell’s nucleus to the protein manufacturing department of the cell where it can be used as the instructions to make specific proteins. MicroRNA (miRNA) are small pieces of RNA that do not code for a particular protein but will stop sections of the protein coding mRNA from being used to create proteins. In this way, they silence specific mRNA molecules. Some of these miRNAs (15 of them that are found in saliva) are associated with have prolonged concussion symptoms (PCS), with five of them accurately identifying the PCS status. Previously the ability to use these markers has been tested in adults. For example, one group of researchers found that not only were miRNA differences detected in injured compared to healthy individuals, but traumatic brain injury triggered different miRNAs than orthopedic injury (Bhomia, Balakathiresan, Wang, Papa, & Maheshwari, 2016). However, as many concussions occur (about two-thirds) in children and adolescents, it is important to find objective markers that doctors and hopefully eventually coaches can use to determine the presence of a concussion and the likelihood for prolonged symptoms.
In a relatively small study with 52 participants who had recently suffered concussions, Johnson, Loeffert, Stokes, et al (2017) tested whether they could detect differences in the miRNAs in the saliva of the participants. They found that there were statistical differences in the levels of the miRNAs in question between the two groups with 85% accuracy, higher than either assessment of other symptoms ~65% or parent reports ~56%.
There needs to be more research obviously, but if a small saliva sample can be used to determine how long and what type of concussion symptoms an individual is likely to experience, we may have the ability to improve concussion management. I would hope that this approach will also be applied to detect the prevalence of concussions within populations and sports that are not typically associated with concussion risk like figure skating. I also hope that this could eventually turn into a portable kit for every coach to objectively assess when an athlete is safe to return.