Athletes who show higher levels of the brain protein tau six hours after a sports-related concussion tend to face a longer period of recovery and delayed return to play, according to a new study published in the journal Neurology.
The findings suggest that tau, a protein that can be measured in the blood, may be a biomarker to help physicians determine an athlete’s readiness to resume play. Tau is known to play a role in the development of chronic traumatic encephalopathy (CTE), frontotemporal dementia and Alzheimer’s disease.
“This study suggests that tau may be a useful biomarker for identifying athletes who may take longer to recover after a concussion,” said Jeffrey Bazarian, M.D., M.P.H. of the University of Rochester Medical Center (URMC), professor of Emergency Medicine and Physical Medicine & Rehabilitation who treats patients at the UR Medicine Sports Concussion Clinic.
“Athletes are typically eager to get back to play as soon as possible and may tell doctors that they’re better even when they’re not. Tau is an unbiased measurement that can’t be gamed; athletes can’t fake it. It may be that tau combined with current clinical assessments could help us make more informed return-to-play decisions and prevent players from going back to a contact sport when their brains are still healing,” Bazarian said.
If an athlete returns to play before the brain has healed, it increases the risk of long-term physical and cognitive problems, especially if another concussion occurs. At this time, there are no objective tools to confirm when it is safe for an athlete to return to the game. Instead, physicians and trainers must make return-to-play decisions based on subjective measures, such as the athlete’s self-reported symptoms and performance on standardized tests of memory and attention.
For the study, the researchers evaluated changes in tau in 46 Division I and III college athletes (male and female) who experienced a concussion. Tau was measured in preseason blood samples and again within six hours following concussion using an ultra-sensitive technology that allows researchers to detect single protein molecules.
The athletes — a mix of soccer, football, basketball, hockey, and lacrosse players — were divided into two groups based on recovery time. Athletes in the “long return to play” group took more than 10 days to recover following concussion; athletes in the “short return to play” group took less than 10 days to return to their sport.
Athletes in the long-return-to-play group showed higher levels of tau in their blood six hours after concussion compared to those in the short return to play group. Higher blood tau concentrations six hours post-concussion consistently predicted that an athlete would take more than 10 days to resume play. Long-return-to-play athletes also showed a jump in tau from preseason levels compared to their short return to play counterparts.
The study showed that tau-related changes occurred in both genders across a variety of sports. However, there were significant differences based on sex: women made up 61 percent of the long return to play group, but only 28 percent of the short return to play group.
Bazarian said that isn’t surprising; it’s well-established that females take longer to recover following concussion than males.
The researchers acknowledged that the study is limited by its small size and that more research is needed to establish tau as a biomarker of concussion severity. Next they plan to test blood samples from athletes immediately following a concussion to see if the relationship between tau and return to play holds true on the sideline in the first few minutes following a head hit.
Bazarian conducted the study with Jessica Gill, R.N., Ph.D. of the National Institute of Nursing Research at the National Institutes of Health.