Brain Protein May Help Assess Recovery Time Following Concussion

An initial study of blood samples from athletes has indicated that elevated levels of the brain protein tau following a sport-related concussion are associated with a longer recovery period and delayed return-to-play (RTP), suggesting that tau may serve as a marker to help physicians determine an athlete’s recovery status and RTP readiness.

Despite the 3.8 million sports-related concussions that occur annually in the United States, there are no objective tools to confirm when an athlete is ready to resume play. Returning to play too early, before the brain has healed, increases an athlete’s risk of long-term physical and cognitive problems, especially if he or she sustains another concussion. Currently, physicians and trainers must make RTP decisions based on an athlete’s subjective, self-reported symptoms and their performance on standardized tests of memory and attention.

A research team led by Jessica Gill, RN, PhD of National Institute of Nursing Research (NINR) at National Institutes of Health (NIH) and Jeffrey Bazarian, MD, MPH, of University of Rochester Medical Center evaluated changes in tau in 46 Division I and III college athletes who experienced a concussion. Tau (which plays a role in the development of chronic traumatic encephalopathy (CTE), frontotemporal dementia, and Alzheimer’s disease) was measured by immunoassay of preseason blood plasma samples and again within 6 hours following concussion. The assay employed an ultra-sensitive digital-array technology that uses a single molecule enzyme-linked immunoarray (Simoa, by Quanterix), enabling detection of single protein molecules.

The athletes – a mix of soccer, football, basketball, hockey and lacrosse players from the University of Rochester and Rochester Institute of Technology – were divided into 2 groups based on recovery time. Athletes in the “long RTP” group took more than 10 days to RTP following concussion, while athletes in the “short RTP” group took less than 10 days to return to their sport.

Individuals in the long RTP group had higher levels of tau in their blood 6 hours after concussion compared to those in the short RTP group. Long RTP athletes also exhibited a jump in tau from preseason levels compared to their short RTP counterparts. Statistical analyses showed that higher blood tau concentrations 6 hours post-concussion consistently predicted that an athlete would take more than 10 days to resume play.

“This study suggests that tau may be a useful biomarker for identifying athletes who may take longer to recover after a concussion,” said Prof. Bazarian, “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 RTP decisions and prevent players from going back to a contact sport when their brains are still healing.”

The study included both male and female athletes and showed that tau-related changes occurred in both genders across a variety of sports. The team found significant differences based on sex: women made up 61% of the long RTP group, but only 28% of the short RTP group. Prof. Bazarian said this isn’t surprising – it is well established that females take longer to recover following concussion than males.

The researchers acknowledge that the study is limited by its small size and that more research is needed to determine if tau can be established as a biomarker of concussion severity and/or recovery. Next steps include getting blood samples from athletes immediately following a concussion to see if the relationship between tau and RTP observed in the study holds true also on the sideline in the first few minutes following a head hit.

The study, by Gill J et al, was published in the January 6, 2017, issue of the journal Neurology.