Chronic Traumatic Encephalopathy in Athletes Involved with Highimpact Sports

Abstract

Background and purpose—Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease
occurring most commonly in athletes and is caused by repeated concussive or subconcussive blows to the
head. The main purpose of this review is to evaluate the published literature on chronic traumatic encephalopathy (CTE) in athletes participating in high-impact sports. In particular, we highlight the significance of
concussive and subconcussive impacts in multiple sports, elucidate the differences between clinical/pathological features of CTE and related neurodegenerative diseases, and provide an explanation for the variation in clinical presentation between athletes of different sports.
Methods—A review targeting relevant publications to CTE was performed. The PubMed/MEDLINE
index was searched for keywords such as “chronic traumatic encephalopathy,” “repetitive traumatic brain
injury,” “mild traumatic brain injury,” and “concussion” from year 1924 through March 1, 2016.
Results—A consensus panel’s recent identification of a pathognomonic pathology in CTE, characterized
by an irregular distribution of phosphorylated tau deposits, is an important step in developing consensus
diagnostic criteria and clinicopathological studies. After review of major clinical studies, evidence suggests
that there are clear differences in neuropathological features, clinical progression, and manifestation of
symptoms between CTE and other neurodegenerative diseases. The literature suggests boxers tend to have
more severe symptoms than other athletes due to more frequent rotational and shearing impacts. Data
regarding genetic predispositions of CTE have been inconsistent in part due to low subject populations.
Positron emission tomography imaging involving tau-binding ligands has recently proven effective in differentiating CTE from control groups and other neurodegenerative diseases.
Conclusions—Further longitudinal studies should be conducted to correlate the number of suffered concussive/subconcussive forces to the likelihood of developing chronic traumatic brain injury symptoms.
Research striving for a reliable antemortem CTE diagnosis would be immensely beneficial, leading to more
accurate estimates of prevalence, allowing clinicians to assess future risk of athletes’ continued participation in sports, and enabling clinicians to make appropriate preventive recommendations.