Concussion Leading to Long Term Cognitive Disability May Be Diagnosed by a Simple Blood Test

The blood level of the protein SNTF (calpain-cleaved alphaII-spectrin N-terminal fragment) measured on the day of a computed tomography (CT)-negative mild traumatic brain injury was used to identify a subset of patients at risk of white matter damage and persistent disability.

Mild traumatic brain injury (mTBI), or concussion, is not typically associated with abnormalities on CT. Nevertheless, it causes persistent cognitive dysfunction for many patients. Therefore, new prognostic methods for mTBI are needed to identify at risk cases, especially at an early and potentially treatable stage.

Investigators at University of Pennsylvania (Philadelphia, USA) in conjunction with colleagues at the Baylor College of Medicine (Houston, TX, USA) identified a new blood biomarker that correctly predicted which concussion victims had suffered white matter structural damage and persistent cognitive dysfunction following an mTBI.

The investigators evaluated blood samples and diffusion tensor images from a group of 38 individuals aged from 15 to 25 years who were participants in a larger mTBI study. Seventeen patients had sustained a head injury caused by blunt trauma, acceleration, or deceleration forces; 13 had an orthopedic injury (OI); and eight were healthy, uninjured, demographically matched controls.

Results revealed that SNTF levels were at least twice the lower limit of detection in 7 of 17 mTBI cases and in 3 of 13 OI cases, but in none of the control subjects. Increased plasma SNTF on the day of injury correlated significantly with cognitive impairment that persisted for at least three months, both across all study participants and also among the mTBI cases by themselves.

"The blood test identified SNTF in some of the orthopedic injury patients as well, suggesting that these injuries could also lead to abnormalities in the brain, such as a concussion, that may have been overlooked with existing tests," said senior author Dr. Douglas Smith, professor of neurosurgery at the University of Pennsylvania. "SNTF as a marker is consistent with our earlier research showing that calcium is dumped into neurons following a traumatic brain injury, as SNTF is a marker for neurodegeneration driven by calcium overload."

"New tests that are fast, simple, and reliable are badly needed to predict who may experience long-term effects from concussions, and as new treatments are developed in the future, to identify who should be eligible for clinical trials or early interventions," said first author Dr. Robert Siman, professor of neurosurgery at the University of Pennsylvania. "Measuring the blood levels of SNTF on the day of a brain injury may help to identify the subset of concussed patients who are at risk of persistent disability."

The paper was published in the November 18, 2013, online edition of the journal Frontiers in Neurology.

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University of Pennsylvania
Baylor College of Medicine