Researchers at the National Institutes of Health (NIH) has found that the blood protein tau could be an important new clinical biomarker to better identify athletes who need more recovery time before safely returning to play after a sports-related concussion. The study, supported by the National Institute of Nursing Research (NINR) with additional funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), published online in the Jan. 6, 2017 issue of Neurology (link is external), the medical journal of the American Academy of Neurology.

Despite the millions of sports-related concussions that occur annually in the United States, there is no reliable blood-based test to predict recovery and an athlete’s readiness to return to play. The new study shows that measuring tau levels could potentially be an unbiased tool to help prevent athletes from returning to action too soon and risking further neurological injury.

“Keeping athletes safer from long-term consequences of concussions is important to players, coaches, parents and fans. In the future, this research may help to develop a reliable and fast clinical lab test that can identify athletes at higher risk for chronic post-concussion symptoms,” said NINR Director Patricia A. Grady Ph.D., R.N.

Athletes who return to play before full recovery are at high risk for long-term symptoms like headaches, dizziness, and cognitive deficits with subsequent concussions. About half of college athletes see their post-concussive symptoms resolve within 10 days, but in others, the symptoms become chronic.

Tau is also connected to development of Alzheimer’s and Parkinson’s diseases, and is a marker of neuronal injury following severe traumatic brain injuries.

In the study, led by Dr. Jessica Gill, NIH Lasker Clinical Research Scholar and chief of the NINR Division of Intramural Research’s Brain Injury Unit, researchers evaluated changes in tau following a sports-related concussion in male and female collegiate athletes to determine if higher levels of tau relate to longer recovery durations.

“Incorporating objective biomarkers like tau into return-to-play decisions could ultimately reduce the neurological risks related to multiple concussions in athletes,” said Gill.

To measure tau levels, a group of 632 soccer, football, basketball, hockey, and lacrosse athletes from the University of Rochester first underwent pre-season blood plasma sampling and cognitive testing to establish a baseline. They were then followed during the season for any diagnosis of a concussion, with 43 of them developing concussions during the study. For comparison, a control group of 37 teammate athletes without concussions was also included in the study, as well as a group of 21 healthy non-athletes.

Following a sports-related concussion, blood was sampled from both the concussed and control athletes at six hours, 24 hours, 72 hours, and seven days post-concussion.

Concussed athletes who needed a longer amount of recovery time before returning to play, (more than 10 days post-concussion) had higher tau concentrations overall at six, 24, and 72-hours post-concussion compared to athletes who were able to return to play in 10 days or less. These observed changes in tau levels occurred in both male and female athletes, as well as across the various sports studied.

Together, these findings indicate that changes in tau measured in as short a time as within six hours of a sports-related concussion may provide objective clinical information to better inform athletes, trainers, and team physicians’ decision-making about predicted recovery times and safe return to play.

Further research will test additional protein biomarkers and examine other post-concussion outcomes.