Researchers from The Sport Science Center at Texas Christian University, Texas Health Sports Medicine, and the University of Wisconsin–La Crosse evaluated the usefulness of biomarker testing in determining the potential extent of brain trauma suffered from repetitive subconcussive head impacts sustained over the course of a college football season. Their findings are reported today in the Journal of Neurosurgery, in the article “Fluctuations in blood biomarkers of head trauma in NCAA football athletes over the course of a season” by Jonathan M. Oliver, Ph.D., and colleagues.

Since individual subconcussive head impacts do not produce symptoms, it can be difficult to ascertain the resultant injury to the brain and to recognize when an athlete should refrain from play. To protect contact-sport athletes throughout the football season, Oliver and colleagues call for the development of a simple, easy-to-use, diagnostic test to identify and monitor accumulation of subconcussive head impacts. The authors suggest periodic measurement of biomarkers of subconcussive head trauma.

In this study, Oliver and colleagues developed a schedule of blood sampling that is cost effective and could fit into the busy schedule of an academic football program. To test the feasibility of this method, they evaluated the usefulness of two well-known biomarkers of head trauma and more severe traumatic brain injury: the tau protein and neurofilament light polypeptide (NF-L – a fitting acronym).

Twenty football players were identified as starters and fifteen as nonstarters. Since starters are involved in more repetitive plays than nonstarters and are consequently more likely to sustain a greater number of head impacts, the researchers expected to see increased concentrations of biomarkers of brain trauma in starters than in nonstarters, who served as controls in this study.

Tau protein did not turn out to be useful in determining repetitive subconcussive head impacts. The levels of tau protein actually decreased over the course of the season for both starters and nonstarters. Also statistical analysis showed that differences in tau concentrations between the two groups of athletes (starters and nonstarters) were not great enough to differentiate between starters and nonstarters.

The results of NF-L measurements provided more insight. Concentrations of NF-L increased in both athlete groups during the competitive season, compared to preseason values. In starters, these increases were significantly higher than preseason values at many time points; in nonstarters, the increases in NF-L concentrations never reached statistical significance. Statistical analysis showed that during periods of repetitive head impacts, differences in NF-L concentrations demonstrated fair to modest accuracy for differentiating between starters and nonstarters.

The researchers conclude that, in this preliminary study, serum NF-L shows some promise as a sensible and reliable biomarker of brain injury due to repetitive subconcussive head impacts. However, they point out that this study is preliminary and that additional, larger studies should be performed to verify this. They believe that the knowledge gained by studies of biomarkers will “lay the groundwork for the eventual development of clinical tools to help reduce the deleterious effects of repetitive subconcussive impacts.”