TAU protein in concussion management: A promising tool?

Between 1.6 and 3.8 million sports-related concussions occur every year in the United States (1). These figures are all the more worrying given that there is no real objective test for identifying and managing concussions. However, recent technological advances have motivated a number of sports medicine researchers to try and develop tools to objectively diagnose this mysterious injury. One test that has been the talk of the concussion industry of late is the Tau protein blood test. Here is a brief analysis of this tool.

Firstly, the TAU (Tubule-Associated Unit) protein is located in the neurons of the central nervous system and has the function of maintaining and stabilizing the microtubules that form the axonal skeleton of the brain. It interacts with tubulin to enable microtubule stabilization and flexibility. When pathological, as in the case of neurodegenerative diseases such as Alzheimer’s or concussion, the Tau protein no longer performs its function. Tau protein aggregates are then seen, ultimately leading to neuron death.

The level of TAU protein in the blood can be used to diagnose a concussion, as well as to monitor a possible return to play, using a scientific and objective measurement. Most current studies link TAU protein to chronic traumatic encephalopathy or Alzheimer’s disease (2). To date, few studies have looked directly at the link between serum tau protein concentration and concussion.

After tracking more than two hundred professional field hockey players, Shahim and colleagues (3) found that blood levels of TAU protein were significantly higher in the 28 players who had just suffered a concussion, compared with the baseline level measured in 47 athletes in pre-season. In addition, these data suggest that blood Tau protein concentration at 1h and 12h post-trauma would be discriminating in order to establish a prognosis for a return to play. In other words, a simple blood test taken 1 hour after the trauma could not only diagnose the concussion, but also predict whether the number of days needed before he can return to play will be more or less than 10 days. Similarly, Gill and colleagues (4) conducted a study on the same subject with collegiate contact sport athletes in the NCAA. The researchers concluded that athletes returning early to play following concussion had lower TAU protein concentrations at 6h, 24h and 72h post-concussion compared to athletes returning late to play. In addition, the same researchers performed characteristic analyses showing that a higher concentration of TAU protein 6h post-trauma also predicted a return to play of more than 10 days. These studies suggest that blood levels of TAU protein could help professionals predict an athlete’s return to play.

This new approach would serve to objectify the diagnosis and prognosis, enabling caregivers to adapt the treatment plan accordingly, and thus be more effective and safer in recommending a return to play. Despite these promising results, more studies are needed to be able to conclude on the effectiveness and real relevance of this approach in the identification and management of concussions. The small number of subjects participating in these studies remains a major problem that limits the interpretation of the results. There are still several stages to go before this method is validated and identified as sufficiently reliable to be used in practice. One thing is certain, these encouraging results bring us ever closer to the discovery of a suitable, objective technique for diagnosing and managing this modern-day sports scourge.

Written by: Dominic Lampron, Joseph Maltais, Gabriel Perreault and Julien Lessard, Physiotherapy Students

References:
1. Thompson, J. & Hagedorn, D. (2012) Multimodal analysis: New approaches to the concussion conundrum. Journal of Clinical Sport Psychology, 5(22-46).
2. Edward, G. & al. (2017) Amyloid-beta and tau pathology following repetitive mild traumatic brain injury. Biochemical and Biophysical Research Communications. Pages 979-1194, 19 February 2017.
3. Shahim, P. et al. (2016) Serum Tau Fragments Predict Return to Play in Concussed Professional Ice Hockey Players. Journal of Neurotrauma, 2016 Nov 15.
4. Gill J. et al. (2017) Acute plasma tau relates to prolonged return to play after concussion. The Official Journal of the American Academy of Neurology, 2017 Feb 07.