Tuesday, February 21, 2017

Plasma tau and return to play after concussion

Gill J, Merchant-Borna K, Jeromin A, Livingston W, Bazarian J. Acute plasma tau relates to prolonged return to play after concussion. Neurology. 2017 Feb 7;88(6):595-602.

To determine whether tau changes after sport-related concussion (SRC) relate to return to play (RTP).
Collegiate athletes underwent preseason plasma sampling and cognitive testing and were followed. After a SRC (n = 46), athletes and controls (n = 37) had sampling at 6 hours, and at 24 hours, 72 hours, and 7 days after SRC. A sample of 21 nonathlete controls were compared at baseline. SRC athletes were grouped by long (>10 days, n = 23) and short (≤10 days, n = 18) RTP. Total tau was measured using an ultrasensitive immunoassay.
Both SRC and athlete controls had significantly higher mean tau at baseline compared to nonathlete healthy controls (F101,3 = 19.644, p < 0.01). Compared to SRC athletes with short RTP, those with long RTP had higher tau concentrations overall, after controlling for sex (F39,1 = 3.59, p = 0.022), compared to long RTP athletes, at 6 (p < 0.01), 24 (p < 0.01), and 72 hours (p = 0.02). Receiver operator characteristic analyses showed that higher plasma tau 6 hours post-SRC was a significant predictor of RTP >10 days (area under the curve 0.81; 95% confidence interval 0.62-0.97, p = 0.01).
Elevated plasma tau concentration within 6 hours following a SRC was related to having a prolonged RTP, suggesting that tau levels may help inform RTP.

“Right now, return-to-play [RTP] is based mostly on subjective measures,” the study leader Jessica Gill, PhD, RN, chief of the brain unit at the National Institute of Nursing Research, told Neurology Today. “If players resume playing too quickly, they may be vulnerable to ongoing symptoms such as headache, dizziness and cognitive deficits, and risk getting a repeat hit to the head before the brain is fully recovered.”

Dr. Gill said it would be helpful to have an objective blood test for tau to add to the clinical exam information and, in some cases, neurocognitive testing currently used to gauge whether a concussed athlete is ready to go back on the field.

“We really have no way to tell patients what is going to happen and prepare them so we can maximize care during recovery,” Dr. Gill said.

She noted, however, that more research is needed as is a refinement of the tau test before it would be ready for clinical use.

“Right now, [the tau test] has about an 81 percent prediction rate, but that's not good enough,” said Dr. Gill, who conducted the study along with researchers at the University of Rochester in New York.

The researchers noted that tau has been linked to axonal damage following traumatic brain injury (TBI), and that a Swedish study of professional hockey players found that higher levels of tau were predictive of a longer return-to-play period….

Dr. Hainline said data from the ongoing study suggests that more attention is being paid to clearing athletes for RTP compared to a few years ago. He said a study from 2001 found that “92 percent of repeat concussions happened with 10 days of a player returning to play.”

Data from the current study of college athletes show that the typical RTP is about 13 days and that the average time for the small percentage of athletes who suffer a repeat concussion is 75 days after return to play, he said.

“That means we are no longer sending people back right away and setting them up for a repeat brain injury,” Dr. Hainline said. “This represents a positive change in the culture of sport.”…

Dr. Diaz-Arrastia said the study, known as TRACK/TBI, plans to enroll 3,000 people; among objectives, the researchers hope to determine whether tau or other biomarkers might be useful to predict which patients may have an extended or incomplete recovery from mild TBI.

While the majority of patients with mild TBI recover quickly, about 10 to 15 percent have lingering symptoms and the mechanisms of why that is the case are not known. Being able to predict whether some are at higher risk for a long recovery might help steer the most vulnerable people toward rehabilitative services.


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