Traumatic Encephalopathy in a Neurodegenerative Disorders Brain Bank

Bieniek KF., Ross OA., Cormier KA., Walton RL.,
Soto-Ortolaza A., Johnston AE., DeSaro P., Boylan KV., Graff-Radford NR.,
Wszolek ZW., Rademakers R., Boeve BF., McKee AC., Dickson DW. Acta Neuropathol 2015;

Take Home Message: CTE
pathology was only detected in individuals with documented participation in
contact sports.

Chronic traumatic encephalopathy (CTE) is a
progressive neurodegenerative disorder, where the onset is linked with a
variety of contact sports. In the past 26 years, over 160 million people
participated in high school or collegiate sports; however, the proportion of
this cohort at risk for developing CTE is unknown. Therefore, the authors conducted
a retrospective cohort study to screen for CTE among individuals with and without
a history of contact sports. Over 1,700 brains without known neuropathologic
conditions were received from a brain bank for neurodegenerative disorders. The
authors collected clinical and demographic data (type of sport, medical family
history, age at death, exposure to non sports-related head impacts) from available
medical records and obituaries. Brain tissue was assessed for neuropathologic
conditions (tau pathology) by immunohistochemistry,
and brain tissue samples were collected to determine genetic association (3
genes; MAPT, TMEM106B, APOE) to CTE. Sixty-six
patients (54 males, 65 Caucasian) participated in a contact sport (34 football,
8 boxers, 7 baseball, 1 basketball, 1 ice hockey, 1 soccer, 1 rodeo, 1 martial
artist). The authors matched every athlete with two people that had no history
of contact sports. Additionally, 66 females were included as controls. Within
the control group, 33 individuals had a history of head trauma (14 falls, 10
motor vehicle accidents, 4 violent assaults, 4 domestic abuse, and 2
unspecified head incidents). The immunohistochemistry results found 32% of
those that participated in contact sport had tau pathology consistent with CTE.
Of the 43 patients that participated in football, 16 had CTE pathology, where 6
played up to high school, 7 played up to college, and 1 played professionally. Among
the 27 former football players with no observed CTE pathology, 15 played up to
high school, and 7 played up to college. No CTE pathology was observed in the
control group. The authors found no differences between clinical or demographic
data between patients with/without exposure to contact sports and CTE
pathology. The authors also did not identify any genetic associations to CTE.

study has important implications for the public health given the number of
people that participate in contact sports. The results of this study suggest
that individuals that participate in contact sports are at a higher risk for having
CTE compared to those that do not participate in contact sports. It was
interesting to note that the authors did not observe any CTE pathologies in the
control group, including those that had previous head trauma. This suggests
that CTE may be related to repetitive impacts, and a single blow is not likely
going to initiate CTE. The authors did not find any genetic association to CTE
but they also found no clinical or demographic differences between those with
and without CTE that participated in contact sports; hence, genetic association
to CTE should not be discounted. This research should be continued in a larger,
prospective cohort that includes more females and other races due to the
current cohort of contact sport cases were predominantly white males. Furthermore,
future studies should try to recruit individuals that are reflective of the
general population of athletes and nonathletes rather than relying on a brain
bank that focuses on neurodegenerative disorders. This will help clarify the
true risk of CTE among athletes in contact sports. It will also be interesting
to see future research verify that individuals who do the assessments are
unaware which specimens came from athletes and nonathletes. In the meantime, medical
professionals need to be aware of these findings and educate patients on the
possible long-term consequences of repetitive head impacts during contact sport

Questions for Discussion:
Do you address CTE pathology when you educate parents, coaches, and athletes
about concussions? Do you believe there would be an increased risk of CTE
pathology in athletes that start contact sport in middle school or younger
youth leagues?

by: Jane McDevitt, PhD
by: Jeff Driban


Bieniek KF, Ross OA, Cormier KA, Walton RL, Soto-Ortolaza A, Johnston AE, DeSaro P, Boylan KB, Graff-Radford NR, Wszolek ZK, Rademakers R, Boeve BF, McKee AC, & Dickson DW (2015). Chronic traumatic encephalopathy pathology in a neurodegenerative disorders brain bank. Acta Neuropathologica, 130 (6), 877-89 PMID: 26518018