PA) - They may want to 'shake it off' and get back into
the game, but a single head injury - even a mild one
- can put athletes at risk for further traumatic brain
injuries. According to researchers at the University
of Pennsylvania School of Medicine, the brain has an
increased vulnerability to severe, perhaps permanent,
injury for at least 24 hours following a concussion.
Their results, published in the November issue of the
Journal of Neurosurgery, have serious implications
for victims of accidents and abuse, as well as amateur
and professional athletes. The researchers believe their
work provides a new model for looking at repetitive
head injuries (RHI). The prospect that athletes may
be returning to the field too soon after a head injury
is alarming, say the researchers. Indeed, the research
was funded by NFL Charities, the philanthropic arm of
the National Football League.
"If you look at the guidelines for mild head injuries
in athletes - from high school to the pros - you'll
see that they are written with little hard scientific
data," said Tracy K. McIntosh, PhD, the
Robert A. Groff Professor in the Penn Department
of Neurosurgery and Director of the Penn Head
Injury Center. "Our findings represent the
first real attempt to look at the science behind head
injuries - and we were startled to see how permanent
the damage can be."
According to the researchers, the effects of RHI may
not be felt for months later. By studying the effects
of brain trauma in mice, the researchers were clearly
able to see how a second head injury exacerbates the
effects of the first one when delivered within 24 hours.
Permanent cognitive damage, however, is not immediate.
In fact, the effects of the trauma seemed transient,
and mice returned to almost normal, doing well in a
number of tests to monitor cognitive and motor skills.
"However, at about 56 days we began to see a measurable
breakdown in motor skills and, subsequently, a breakdown
in the cells of the brain," said McIntosh. "This
correlates with what we know about the nature of repetitive
head injuries in humans, and its role as a factor in
There is already a growing body of data that suggests
that those that suffer RHIs in sports may be at greater
risk for neurodegenerative diseases later in life. In
fact, the damage to the brain found in victims of Dementia
Pugilistica, or "Punch Drunk Syndrome," closely
resembles that of Alzheimer's patients.
Although they do not know the exact mechanism that leads
to damage after repetitive head injuries, McIntosh and
his colleagues are interested in one brain cell protein
that has also been implicated in contributing to Alzheimer's.
Accumulations of the beta-amyloid precursor protein
(b-APP) was found in great quantities in the neurons
of mice that received RHIs, accompanied by an increase
in the amount of dead or dying neurons. They hypothesize
that the damage from injury causes b-APPs to gradually
accumulate in the cytoskeleton of neurons, which serves
as the support structure for the cell as well as the
roadway by which nutrients travel throughout the cell.
This roadblock slowly chokes off the cell and eventually
leads to its death.
"Clearly, we do not always recognize concussions
for what they are: brain injuries," said McIntosh.
"The damage is not always noticeable either. That
is, you do not have to fracture your skull to injure
According to McIntosh, traumatic brain injury (TBI)
is a 'silent epidemic' in our society. Each year, an
estimated two million cases of TBI occur in the United
States, with approximately 500,000 cases serious enough
to require hospitalization. Most patients, however,
do not seek professional medical help or are discharged
immediately after examination. As yet, there is no medical
treatment for TBI.
"The desire to get back into the game is admirable,
but ultimately not worth the risk," said McIntosh.
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