Fla. — Scientists have recently found evidence that
professional football players are susceptible to a progressive
degenerative disease, chronic traumatic encephalopathy (CTE),
which is caused by repetitive brain trauma. Now, researchers
on Mayo Clinic’s Florida campus have discovered a
significant and surprising amount of CTE in males who had
participated in amateur contact sports in their youth.
one-third of these men whose brains had been donated to the
Mayo Clinic Brain Bank had evidence of CTE pathology. CTE only
can be diagnosed posthumously.
study, published in the December issue of Acta
Neuropathologica, links amateur contact sports — football,
boxing, wrestling, rugby, basketball, baseball and others
played while in school — with the development of CTE, which
when severe can affect mood, behavior and cognition.
32 percent of CTE we found in our brain bank is surprisingly
high for the frequency of neurodegenerative pathology within
the general population," says the study’s lead author,
Kevin Bieniek, a predoctoral student in Mayo Graduate School’s
Neurobiology of Disease program.
1 in 3 individuals who participate in a contact sport goes on
to develop CTE pathology, this could present a real challenge
down the road," Bieniek says. It remains to be determined
if the brain changes produce any observable effects on
behavior or cognition of the former athletes.
study is the first to use CTE neuropathologic criteria
established by the National Institute of Neurological
Disorders and Stroke (NINDS) earlier this year to look for
incidence of the disease in nonprofessional athletes, says the
study’s senior author, Dennis Dickson, M.D., a
neuropathologist at Mayo Clinic.
these criteria, Bieniek’s report is the first detailed
description of CTE pathology in a brain bank. As such, his
work is groundbreaking," Dr. Dickson says. "The
frequency with which he found CTE pathology in former athletes
exposed to contact sports was surprising. It is pathology that
had gone previously unrecognized." Bieniek is a member of
Dr. Dickson’s laboratory.
purpose of our study is not to discourage children and adults
from participating in sports because we believe the mental and
physical health benefits are great," Bieniek says.
"It is vital that people use caution when it comes to
protecting the head. Through CTE awareness, greater emphasis
will be placed on making contact sports safer, with better
protective equipment and fewer head-to-head contacts."
led the team that examined the clinical records of 1,721 cases
in the Mayo Clinic Brain Bank. They found 66 males who had
documented participation in contact sports during their youth
and young adult years. Of these cases, 32 percent had CTE
pathology when the researchers examined brain tissue. In
comparison, none of the 198 brains of individuals without
documentation of participation in contact sports, including 66
women, had CTE pathology.
researchers also compared a number of clinical and genetic
features between cases with and without CTE pathology, and
found two genetic markers that seemed to possibly modify risk
of developing CTE. "These markers need to be further
studied in a larger group of CTE cases, but they could be very
important in determining whether an individual is at greater
risk of developing these brain changes," Bieniek says.
notes that the Mayo Clinic Brain Bank includes donors who have
died with varying disorders of dementia. "We decided to
examine our brain bank of neurodegenerative disorders, because
CTE, found in older people, rarely occurs in isolation,"
Bieniek says. "Many cases of CTE previously reported have
other neurodegenerative pathologies in addition to CTE. So,
the same risk factors that may increase risk for other
neurodegenerative diseases could very well play a role in
development of CTE."