A concussion diagnosis
depends upon a careful assessment of symptoms. Now the largest study to date of
sports-related concussion points to a potential medical assist when evaluating
a college athlete for this injury.  

Certain proteins in the blood are elevated after a
concussion
, researchers report online
January 24 in JAMA Network Open. That
discovery may one day help with distinguishing athletes who have suffered this brain
injury from those who haven’t.

Researchers took blood
samples pre- and post-injury from 264 college athletes who had concussions
while playing football, rugby and other contact sports from 2015 to mid-2018.  Blood levels for three proteins were higher
than they were before the injury occurred, the researchers found.

Each of the three proteins
can serve as a sign that damage has occurred to a different type of brain cell,
says Michael McCrea, a neuropsychologist at the Medical College of Wisconsin in
Milwaukee. Glial fibrillary acidic protein is released in response to injury to
glial cells, which provide support to nerve cells in the brain. Ubiquitin
C-terminal hydrolase-L1 signals that nerve cells have been injured, and tau is
a sign of damage to axons, which transmit nerve impulses. These proteins have
been evaluated in past research as potential makers of more severe traumatic
brain injury.

McCrea’s team also measured these
proteins in 138 athletes who played contact sports but were not concussed, and
in 102 athletes who did not have the injury and played noncontact sports. The protein
levels for these two groups remained steady throughout the study. If there had
been large variability in the protein levels in non-concussed athletes, McCrea
says, that would have undermined the association between
the proteins and concussion.

Traumatic brain injuries —
which can result from a blow to head during falls, car accidents or while
playing sports, for example —  can range
from severe to mild. Sports-related concussions are considered mild traumatic
brain injuries, McCrea says. An estimated 10,560 sports-related concussions are
reported by college athletes in the United States each year, according to a 2015 American Journal of Sports Medicine
study.

A person suffering a
concussion generally experiences one or more of the following symptoms: headache,
nausea, dizziness, confusion and a brief loss of consciousness. But the
physical symptoms may not always make the diagnosis clear; a headache after a
tackle might not necessarily be a sign of concussion. So researchers have been
looking for chemical signals, called biomarkers, that may help reveal when a
concussion has happened.

It will take much more work before
concussion biomarkers would be ready to use in the clinic or on the field,
McCrea says, including determining which combination of proteins are most reliably
linked to the injury and how to quickly test for them.  

“The goal of a biomarker is
to provide a reproducible and accurate indicator of a medical state,” says
Juliana VanderPluym, a neurologist at the Mayo Clinic in Phoenix, Ariz., who
was not involved in the study.  She notes
that “it is important to consider [biomarkers] as an aide, and not necessarily
as the final determinant” of a diagnosis. For example, if an athlete gets
tackled in a game and reports symptoms that suggest a concussion, she says, but
has normal levels of these proteins, should that athlete be allowed to return
to the game? “These are questions that we will need to address before
biomarkers become part of clinical practice.”

Around 80 percent of the
study participants were male athletes. “It will be important in future studies
to see whether the results are similar” for women, says VanderPluym. Female
college athletes have a higher rate of concussions than males, according to a
2016 study in the Journal of Athletic
Training
. Women also can experience more severe symptoms after a blow to
the head than their male counterparts and may experience worse damage to the brain (SN: 7/31/18).