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Blood Tests May Help Diagnose Concussions

June 19, 2014
Elevated tau protein levels found to be useful biomarker of concussions among Swedish hockey players.

Tau protein levels and other types of biomarkers may help doctors better diagnose concussions and even monitor symptoms, according to new research. A recent study looked at professional hockey players in Sweden, monitoring their tau protein levels after physical exertion and concussion injuries.

Of the 288 player studied, 28 experienced concussions. The median total tau (t-tau) level was calculated from blood samples taken 1 hour after their injuries occurred, which came out to 10 pg/mL (range 2-102), an increase compared to the preseason samples of 47 other players, which was 4.5 pg/mL (range 0.06-22.7), according to Pashtun Shahim, MD, a researcher at the University of Gothenburg in Mölndal, Sweden.1

The study also looked at other biomarkers like S-100 calcium-binding protein B (S-100B) and levels of neuron-specific enolase (NSE). While S-100B showed similar results to t-tau levels, NSE did not, Dr. Shahim and colleagues reported in JAMA Neurology.

Median S-100B levels increased in concussed players compared to preseason levels, measuring 0.075 μg/L compared with pre-injury levels of 0.045 μg/L. NSE, by contrast, showed no noticeable changes before and after injury—pre-concusion NSE was 6.5 μg/L compared with post-concussion levels at 6.1 μg/L, a difference of 0.4 μg/L (P = 0.10).

S-100B and NSE levels also seemed to rise much higher after a game with purposefully light physical contact, which reduced the incidence of concussion injuries, making these biomarkers less predictable than t-tau, which showed no significant changes. Other researchers independent to the study believe that this may be indicative of S-100B and NSE levels being less reliable for detecting concussions and persistent symptoms.

According to Joshua Gatson, PhD, from the University of Texas Southwestern Medical Center in Dallas, Texas, and Ramon Diaz-Arrastia, MD, PhD, at the Uniformed Services University of the Health Sciences in Bethesda, Maryland, the study suggests that when monitoring milder concussions, S-100B and NSE levels are less useful as “traumatic brain injury biomarkers,” citing that their increases after the friendly game may prove their “lack of specificity” for detecting brain injuries.

T-tau levels did not fluctuate after the friendly game, however, and Drs. Gatson and Diaz-Arrastia believe this may stem from the fact that t-tau levels stem from neurons in the central nervous system being released after a brain injury. The physical exertion and muscle bruising may have been the cause of the S-100B and NSE levels changing, they wrote.

According to Dr. Shahim and colleagues, the recent study was a significant first step in measuring “T-tau in serial plasma samples from professional athletes” that have suffered from sports-related concussions. Other studies that looked at tau protein levels have been in people resuscitated after cardiac arrestl thet found that the levels were highest in those with the poorest outcome.2

Such recent findings on tau proteins may prove that this biomarker could be a helpful indicator of axonal injury, Dr. Shahim and colleagues wrote.

The study was conducted in collaboration with Swedish Hockey League during their 2012-2013 season. Players who suffered concussion injuries had their blood samples taken at 1, 12, 36, 48, and 144 hours after the injury occurred. The study also used a very new assay product called Quanterix that was used to measure the tau protein levels.

Two researchers involved in the study, Dr. David H. Wilson and Dr. Jeffrey Randall, are employees of Quanterix Corp. Dr. Henrik Zetterberg and Dr. Kaj Blennow are co-inventors of the US patent application for plasma tau as a brain injury marker. Dr. Blennow has also been advisor for Eli Lilly, Kyowa Kirin Pharma, Pfizer, and Roche. No other authors reported conflicts of interest.

The study was funded by grants from the Swedish Medical Research Council.

Last updated on: May 19, 2015