Traumatic brain injuries (TBIs) can result from a blow or jolt to the head or an object going through the skull. Millions of sports-related mild TBIs, or concussions, occur each year in the United States. Athletes who return to play before they’re fully recovered are at high risk for long-term symptoms like headaches, dizziness, and cognitive deficits if they have future concussions.
The tau protein is a marker of brain cell injury following severe traumatic brain injuries. The protein has also been linked to development of Alzheimer’s and Parkinson’s diseases. To determine if higher levels of tau relate to longer recovery times, a team led by Dr. Jessica Gill of NIH’s National Institute of Nursing Research (NINR) examined changes in tau levels after sports-related concussions. The study was supported by NINR and NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Results were published online in Neurology on January 6, 2017.
The researchers first measured pre-season levels of tau and cognitive performance in a group of 632 soccer, football, basketball, hockey, and lacrosse athletes from the University of Rochester. The athletes were then followed during the season for any diagnosis of a concussion.
Forty-three of the players developed concussions during the study. Following the diagnosis, blood samples were taken from the concussed athletes at 6 hours, 24 hours, 72 hours, and 7 days post-concussion. For comparison, blood samples were also taken from a control group of 37 teammate athletes without concussions. A group of 21 healthy non-athletes who were similar in age and sex served as another control group.
Concussed athletes who needed more than 10 days of post-concussion recovery time before returning to play had higher average tau levels at 6, 24, and 72 hours post-concussion than athletes who were able to return to play in 10 days or less. This was observed in both male and female athletes, as well as across the various sports studied.
Together, these findings suggest that changes in tau measured within 6 hours of a sports-related concussion may provide a tool to inform better decision-making about predicted recovery times and safe return to play.
“Keeping athletes safer from long-term consequences of concussions is important to players, coaches, parents, and fans,” says NINR Director Dr. Patricia A. Grady. “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.”
For unknown reasons, both athlete groups had significantly higher tau levels than the non-athlete controls. The scientists plan to test additional biomarkers and examine other post-concussion outcomes in the future.