Bottom Line: Ice hockey players in Sweden with a sports-related concussion had higher levels of the blood biomarker total tau (T-tau), which suggests the central nervous system (CNS) protein may be a tool for diagnosing concussions and making decisions about when players can return to play. 1
Author: Pashtun Shahim, M.D., of Sahlgrenska University Hospital, Sweden, and colleagues.
Background: Concussion or mild traumatic brain injury in athletes who play competitive contact sports, such as ice hockey, American football and boxing, is a growing problem. While mild concussions generally cause no loss of consciousness, they can induce other symptoms such as dizziness, nausea, trouble concentrating, memory problems and headaches. Severe concussions can cause a loss of consciousness. Most concussions resolve in days or weeks, but some patients can suffer symptoms more than a year after injury.
How the Study Was Conducted: The authors examined whether sports-related concussions were associated with elevated levels of blood biochemical markers of injury to the CNS. Swedish Hockey League players (n=288) underwent preseason baseline examination for concussion and some underwent preseason blood testing. Of the 288 players, 35 had a sports-related concussion from September 2012 through January 2013, and 28 of those players were included in the study. Players underwent repeated blood testing in the hours and days after their injuries and when they returned to play.
Results: Players who had concussions had increased levels of the injury biomarker T-tau compared with preseason levels. The highest levels of T-tau were measured in players during the first hour after a concussion and declined during the first 12-hour period but remained elevated six days later compared with preseason blood results. T-tau levels after concussion also were associated with the number of days it took for concussion symptoms to resolve and for players to safely return to competition.
Discussion: “Plasma T-tau, which is a highly CNS-specific protein, is a promising biomarker to be used both in the diagnosis of concussion and in decision making as to when an athlete can be declared fit for RTP (return to play).”
In a related editorial 2, Joshua Gatson, Ph.D., of the University of Texas Southwestern Medical Center, Dallas, and Ramon Diaz-Arrastia, M.D., Ph.D., of the Uniformed Services University of the Health Sciences, Bethesda, Md., write: “Clinicians evaluating and treating patients who have sustained TBIs (traumatic brain injuries) in the mild end of the spectrum and present after a brief period of altered awareness and brief (or no) loss of consciousness are faced with several questions that could benefit from the availability of validated blood biomarkers.”
“The study by Shahim et al in JAMA Neurology represents an important contribution to this field and introduces an innovative technology that promises to have wide applicability. … The main finding of the study is that total tau is elevated in plasma after concussion, and the elevation persists for several (up to six) days. This is an important finding, as tau is a widely studied brain-specific molecule involved in a wide range of neurodegenerative conditions, including chronic traumatic encephalopathy (a degenerative brain disorder),” they continue.
“Future studies should address whether elevated plasma tau identifies athletes who have sustained multiple mTBIs (mild traumatic brain injuries) and are at risk for developing chronic traumatic encephalopathy,” they conclude.
1. JAMA Neurol. Published online March 13, 2014. doi:10.1001/.jamaneurol.2014.367
2. JAMA Neurol. Published online March 13, 2014. doi:10.1001/.jamaneurol.2014.443. A