A Blood Test to Diagnose Concussions!

Dr. Sharon Orrange
Dr. Orrange is an Associate Professor of Clinical Medicine in the Division of Geriatric, Hospitalist and General Internal Medicine at the Keck School of Medicine of USC.
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There is a new appreciation for concussions and the long-term effects they can have on younger adults. How can you really tell if you or your child had a concussion, and what would you do differently? A very cool study published in JAMA Neurology reveals a potential blood test for concussion. This matters because there is evidence that kids with sports-related concussions need to give their brains a rest by avoiding physical activity and abstaining from cognitive challenges such as reading, texting, or playing video games for several days. The brain heals faster that way.

Blood levels of a protein that signals damage to the axons in the brain, called total-tau (T-tau), could be used as a blood test to discern the severity of concussions in athletes and help decide when it is safe to return to play. The authors report that T-tau is a promising biomarker for the diagnosis and prognosis of concussion in athletes.

Hockey players were the subject of this study, which showed that players with sports-related concussions had higher levels of T-tau. The highest levels of T-tau (5 to 10 times normal) were measured immediately after the injury, then the levels continued to decline back to normal. Another key finding was that T-tau concentrations 1 hour after concussion predicted the number of days it took for the concussion symptoms to resolve and the players to return to play safely.

Why T-tau? The protein T-tau is usually found only in the cerebral spinal fluid (CSF), but gets into the bloodstream after concussion if the blood-brain barrier is damaged (yuck). So, raised levels are a marker of brain injury. You may remember hearing about T-tau because it is increased in the CSF in Alzheimer’s disease. In any case, more studies need to be done to sort out the usefulness of the blood test for T-tau to diagnose concussion, but it’s an interesting start.

Dr O.

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