Ann McKee is the director of BU’s CTE Center. Credit: Asia Kepka
Studying the brains of 152 young athletes exposed to repetitive head impacts (RHI) who died before the age of 30, the foremost experts in chronic traumatic encephalopathy (CTE) found that nearly half of them had neuropathological evidence of the disease at the time of their death. This includes a 28-year-old female collegiate soccer player, the first American female athlete to be diagnosed with CTE.
The study, published in JAMA Neurology, was led by Ann McKee, the director of the Chronic Traumatic Encephalopathy (CTE) Center at Boston University. All of the samples were pulled from the BU-led UNITE Brain Bank, a repository of more than 1,400 brains donated after death for study, which is run in partnership with the U.S. Department of Veterans Affairs and the Concussion Legacy Foundation.
According to study results, 41% (63) of the donated brains had neuropathological evidence of CTE. More than 70 percent of those diagnosed were amateur athletes.
Almost all CTE diagnoses were mild, with 39 athletes showing stage I CTE and 21 with the pathology of stage II CTE. However, three brains were diagnosed with stage III CTE, including one former NFL player, one college football player, and one professional rugby player. No brain donors were diagnosed with the most advanced stage IV CTE.
“It seems to be well accepted now that you can play at a very high level of elite American football or ice hockey and get CTE,” said McKee. “But we’re seeing the beginnings of this disease in young people who were primarily playing amateur sports.”
Male football players dominated the study sample, with 92 (61% of the overall sample) playing American football as their primary sport. Eleven of 12 professional football players were diagnosed with CTE, including 11 of 11 NFL players. But the research team also saw CTE in amateur football players—21 men diagnosed with CTE played in college and 16 played in high school. For those who played football, duration of playing career was significantly longer in those with CTE compared with those without CTE.
Of the 16 ice hockey players in the sample, 6 (38%) were diagnosed with CTE. Four were amateur ice hockey players diagnosed with stage I or II CTE. The researchers found that the sole NHL player had stage II CTE, while the one non-NHL professional hockey player had stage I CTE.
Additionally, 4 of 23 athletes (17%) who played soccer were diagnosed with CTE—two male high school players, one male semiprofessional player and one female collegiate player. The female player was 28-years-old at the time of her death. She had played soccer as a forward for 18 years, beginning at age 3 and playing through three years of Division I collegiate soccer. In addition to two concussions without loss of consciousness while playing the sport, at age 24, she experienced a syncopal episode and a traumatic brain injury with loss of consciousness for 3 minutes. Four years later, she developed paranoia and suicidal thoughts. At 28 years of age, she died by suicide. The researchers’ postmortem examination revealed stage I CTE. Among the 152 athletes, suicide was the most common cause of death, followed by unintentional overdose.
According to McKee and collaborators, the young athletes diagnosed with CTE often showed other evidence of brain injury, including the presence of a cavum septum pellucidum, enlargement of the ventricles, and more perivascular macrophages in the white matter. One 27-year-old brain donor with CTE stage II had sparse Lewy bodies in the medulla, and a semiprofessional soccer player was diagnosed with both stage II CTE and amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s Disease.
For football players, specifically, years of play was significantly associated with perivascular macrophages in the frontal white matter. Those diagnosed with CTE played, on average, 3.8 years more than those without the disease.
“This study clearly shows that the pathology of CTE starts early,” said McKee. “The fact that over 40% of young contact and collision sport athletes in the UNITE brain bank have CTE is remarkable considering that studies of community brain banks show that fewer than 1% of the general population has CTE.”
The researchers also found that clinical symptoms were common among the athletes, whether or not they had CTE. These symptoms included depression (70%), apathy (71%), difficulty controlling behaviors (57%), and problems with decision making (55%). Substance abuse also was frequent, with alcohol abuse present in 43% and drug abuse in 38% of the athletes.
The scientists say further necessary research includes analyzing young brain donors not exposed to contact and collision sports to better understand non-CTE brain damage from RHI, and what symptoms are related to concussions, RHI and/or CTE.
McKee and colleagues recently developed the first CTE Prevention Protocol, a series of evidence-based recommendations to help sports organizations develop policies, alongside their existing concussion protocols, to reduce CTE risk.