Concussion Symptoms Linked to Proteins in Spinal Fluid for First Time, Suggesting Possibility of Diagnostic Test

Levels of certain proteins in the brain and spinal fluid of people who suffer continuing issues as a result of concussions are different from those who haven’t had concussions, according to a new small study published today in JAMA Neurology, raising the possibility that doctors may soon have objective markers to assess the severity of brain damage after head trauma.

The study is the first to examine biomarkers in the cerebrospinal fluid of athletes with post-concussion symptoms.

Researchers studied 31 people, 16 of whom were Swedish professional hockey players with post-concussion syndrome -- a condition in which patients experience symptoms such as headaches, mood changes and difficulty concentrating for extended periods of time after a head injury. Players were compared to 15 neurologically healthy individuals.

After sampling the cerebrospinal fluid of all participants, researchers found that compared to the neurologically healthy individuals or players whose post-concussive syndrome symptoms lasted for less than a year, players who had symptoms that lasted for more than year had higher levels of proteins called Neurofilament Light (NF-L) proteins -- found in the white matter of the brain -- suggesting injury to areas that contain nerve fibers connecting various structures within the brain.

NF-L proteins were also higher in players who reported having had more concussions and those who had more severe post-concussion symptoms.

Researchers also found that players with post-concussion syndrome had lower levels of amyloid-beta in their spinal fluid. Amyloid-beta is protein that can clump together to form plaques that are associated with Alzheimer's disease. The lower levels found in the study suggests amyloid is being deposited in the brain, as is the case in Alzheimer’s disease.

“These findings could inform decisions about whether to continue to play or not,” Dr. Michael DeGeorgia, director of the Neurocritical Care Center at University Hospitals Cleveland Medical Center, told ABC News. DeGeorgia was not involved in this study.

“It could affect decisions around post-concussion syndrome management. If you have higher levels of NF-L proteins or low levels of amyloid, you may be on a trajectory toward more serious neurologic illness. The second or third concussion should be taken even more seriously," DeGeorgia said.

Every year, there are between 1.6 million and 3.8 million sports-related concussions in the United States, according to the U.S. Centers for Disease Control and Prevention. Symptoms of concussion usually resolved within days to weeks, but in about 10 to 15 percent of people, symptoms can last for more than 3 months, according to the CDC.

There is growing evidence that repeated mild traumatic brain injury -- often experienced by military personnel as well as those playing contact sports like football and hockey -- can lead to persistent long-term symptoms, including headaches, mood changes, and even a progressive neurodegenerative condition known as chronic traumatic encephalopathy (CTE). Currently, CTE can only be diagnosed posthumously by directly examining the brain with an autopsy.

“I’m not sure how soon this will be used in clinical practice,” DeGeorgia said, noting that the method examined in this study requires a lumbar puncture to draw a sample of spinal fluid.

"On the other hand, if you are a professional football or hockey player at high risk, I would think it may be worth an occasional lumbar puncture to see how levels of these proteins are being affected by head trauma," he added.

Until now, there haven’t been objective tools to measure the extent to which post-concussion symptoms are caused by injury to neurons in the brain. The diagnosis of post-concussion syndrome is based on symptoms reported by patients.

But the biomarkers identified in this study could possibly be used to assess the severity of brain injury in patients after concussions, as well as predict who might be at higher risk for developing CTE and potentially allow for behavioral modifications or other recommendations to prevent further deterioration.

“We now have increasing evidence that repeated mild traumatic brain injury can lead to significant and long-lasting structural changes in the brain,” DeGeorgia said. “We need to take all precautions necessary, not just for professional athletes, but amateur athletes, too -- kids playing soccer, high school football players. When anyone has any symptoms of concussions, we need to take that very seriously.”

Dhruv Khullar, M.D., M.P.P., is a resident physician at Massachusetts General Hospital and Harvard Medical School. He is also a resident in the ABC News Medical Unit. Follow him on Twitter @DhruvKhullar.