Date: 29th March 2021
Traumatic brain injury (TBI) is the leading cause of death and disability in people younger than 45 in Western countries, and is a form of acquired brain injury. However, a high percentage of cases go misdiagnosed or unidentified, and there are extremely poor objective diagnostic tests after a concussion that can potentially re-expose individuals to further risk if the initial trauma has not been resolved. Now, researchers have identified unique signatures of concussion in saliva of male athletes diagnosed with concussion, paving the way for the first non-invasive clinical test for concussion for use in sport and other settings.
It is becoming increasingly clear that professional athletes who engage in contact sports such as rugby, American football, football/soccer and boxing are prone to repetitive head or neck trauma and have a significant increase in the risk of neurodegenerative diseases such as dementia, Alzheimer’s and Parkinson’s disease as well as motor neuron disease. The conventional method of diagnosing head trauma is by neuroimaging such as CT and MRI scanning. However, diagnosis relies on a clinician’s interpretation of a range of evaluations, which are not specific for concussion, and standard imaging methods lack the resolution to identify the majority of injuries as they don’t result in structural abnormalities.
Now, researchers from the University of Birmingham, UK, led by Antonio Belli, in collaboration with the Rugby Football Union, Premiership Rugby, and Marker Diagnostics, have identified diagnostic small non-coding RNAs (sncRNAs) in the saliva of concussed elite rugby athletes, leading to the commercialisation of a patented salivary concussion test as an over-the-counter test for elite male athletes.
The team started by collecting saliva from male professional rugby players in England. Preseason samples, as well as samples collected during standardised head injury assessments (HIA) were taken in-game, post-game and 36-48 hours post-game in addition to control samples. Diagnostic sncRNAs were identified with next generation sequencing and validated using quantitative PCR in 702 samples.
32 different sncRNAs were identified as potential concussion biomarkers across the three time points that were differentially expressed in rugby players with a clinical diagnosis of concussion (HIA+) compared with those cleared of concussion after examination (HIA-). They identified significant dynamic changes in the concentration of the sncRNAs between time points after concussion, suggesting a rapid evolution of biological responses and the cellular processes they regulate occurs after head trauma.
In order to develop a rapid, diagnostic test for both symptomatic and asymptomatic concussions which could track full recovery, the team had to narrow down the number of diagnostic sncRNAs. They therefore used a panel of 14 of these different biomarkers, which they showed could accurately predict clinical diagnosis of concussed subjects from all other groups, immediately after the game and 36–48 hours later, in 94% of cases.
In collaboration with Marker Diagnostics, a subsidiary of Swiss biotechnology company Marker AG, the process of commercialising the patented salivary concussion test as an over-the-counter test for elite male athletes is underway. It has also obtained a CE Mark for test, which has been named MDx.100.
Conclusions and future applications
The team here has undertaken a large prospective observational study of non-invasive concussion biomarkers, called Study of Concussion in Rugby Union through MicroRNAs (SCRUM). Identifying a panel of unique signature sncRNAs in the saliva of male athletes that is highly predictive of concussion.
The development of a non-invasive, salivary concussion test with high accuracy is a potential game changer and will be a powerful tool for clinicians to diagnose concussion more consistently and accurately. In particular, in setting such as grass roots sports, where specialists are not available, it will contribute to a new global standard of care for the injury and a meaningful reduction of the cost and health burden associated with concussion. This is likely to significantly impact non-professional players, whose access to specialists on field is very limited, and where the overwhelming majority of sport-related concussions occur. The researchers are now planning to expand the test on groups that were not in the SCRUM study, such as women, young athletes and community sports players.
Away from grass roots sports, this test has far reaching implications. From the military, to roadside accidents, perhaps even schools, the ability to diagnose concussion in a non-medical environment is a very attractive option and one that will impact the lives of many people, particularly for injuries without significant visible symptoms.
With a rapid, accurate diagnostic test in place, this should add to the increasing research into TBI. Scientists have recently developed a nanoparticle (NP) platform that enabled brain delivery of siRNA for the treatment of TBI, allowing them to inhibit the expression of a key neurodegenerative player by up to 50%. Together, research like this should change the way we diagnose and treat TBI, and offer early treatment options to avoid the development of diseases later in life that are associated with repetitive head trauma.
For more information please see the press release from the University of Birmingham
Di Pietro, V., P. O’Halloran, C. N. Watson, G. Begum, A. Acharjee, K. M. Yakoub, C. Bentley, D. J. Davies, P. Iliceto, G. Candilera, D. K. Menon, M. J. Cross, K. A. Stokes, S. P. Kemp and A. Belli (2021). “Unique diagnostic signatures of concussion in the saliva of male athletes: the Study of Concussion in Rugby Union through MicroRNAs (SCRUM).” British Journal of Sports Medicine: bjsports-2020-103274.
https://doi.org/10.1136/bjsports-2020-103274
