Experts are urgently calling for more oversight of junior contact sports, after the largest-ever study of chronic traumatic encephalopathy (CTE) in young athletes found signs of the condition in 63 out of the 152 young brains that had been autopsied.
The subjects of the study by the Boston University CTE Centre had competed in youth, high school and college competitions, and all died before the age of 30, write Stephen Townsend, Alan Pearce, and Kathleen Bachynski in The Conversation, who said the findings could have major implications for sporting leagues worldwide.
The case series includes the first American woman athlete diagnosed with the disease, just months after the Australian Sports Brain Bank reported the world’s first finding of CTE in a female athlete.
Like other dementias, CTE is often assumed to be a disease that develops later in life, but neuropathologist and Boston University CTE Centre Professor Ann McKee said: “This study clearly shows that the pathology of CTE starts early.”
The findings should push sporting organisations to do more to protect the brains of all athletes, especially in junior and recreational competitions.
CTE and young athletes
CTE is a devastating and currently incurable form of dementia that causes neurodegeneration and has long been associated with contact sport participation.
While dementias like CTE are often considered diseases of the elderly, a number of high-profile cases of CTE have been identified among younger athletes.
In Australia, NRL player and coach Paul Green was 49 when he died and was later found to have CTE. Former AFLW player Heather Anderson was only 28. Another study in the United States also found CTE in the brain of an 18-year-old athlete.
The disease is known to cause mood disorders and behaviour changes. People with CTE may be at higher risk of suicide.
These cases and the latest Boston University study indicate the risk of developing CTE is not restricted to those in their middle or older years.
Although there is some evidence that developing brains are more vulnerable to trauma – it creates a chronic inflammatory response affecting brain development – the pathology of CTE is still being studied.
The risk factors for young athletes are complex and multi-faceted but it is likely that playing junior contact sport heightens an athlete’s risk of developing neurodegenerative diseases as an adult.
The strongest predictor for developing CTE is cumulative exposure to repeated brain trauma, rather than the number of diagnosable concussions.
Prolonged exposure to repeated low-level impacts appears to produce a greater lifetime volume of brain trauma, compared with athletes who sustain a small number of more forceful injuries.
Again, the reasons for this dynamic require further study. One potential explanation is that low-level impacts, which often do not reach the clinical threshold for a concussion diagnosis, are easier to ignore and play through.
For the athletes in the Boston University study to have developed CTE before of 30, it is possible they were exposed to repeated brain trauma from an early age through youth sport.
Are contact sports safe for kids?
Public health advocates in a number of countries have long expressed concerns about the risks of contact sport for children.
Improved oversight would go some way toward reducing the serious health risks of mild traumatic brain injury (concussion). These include post-concussion syndrome (where symptoms do not resolve within the expected time period of about one month) and second impact syndrome, (where a young athlete who has previously been concussed receives a second impact either on the same day or up to a week later, resulting in catastrophic outcomes).
Although professional athletes are increasingly monitored for brain injuries, these practices are not consistently in place for semi-professional, club or junior competitions.
It is essential sports bodies implement the same reporting, monitoring and exclusion protocols all the way through their competitions, especially in junior sport.
First steps
Existing concussion guidelines are not designed to account for the types of sub-concussive injuries (where an impact does not result in observable symptoms) most strongly associated with CTE. To protect them from the disease, contact sporting bodies must reduce young athletes’ lifetime exposure to brain trauma. One way to do this would be to restrict contact in training and games for juniors.
Some sporting bodies have already taken the initial steps. Australian Rules football players are restricted to modified tackling until the age of 12. The National Rugby League will soon implement a ban on tackling until midway through under-7s competitions.
The US Soccer Federation prohibits children under 11 from heading the ball, and the UK Football Association will trial a ban on deliberate heading before age 12 – a clear acknowledgement of the dangers of repetitive low-grade brain trauma.
The prevalence of CTE in this latest study from the US, where athletes routinely wear helmets to play football and ice hockey, is further evidence that helmets do not protect young players from concussions or the risk of CTE.
The study shows CTE can develop in young brains, and builds off previous research suggesting the origins of this pathology may lie in junior contact sport.
To protect players from neurodegenerative diseases like CTE, sports must reduce cumulative exposure to brain trauma for all athletes, beginning with the junior leagues.
Stephen Townsend, Lecturer, School of Human Movement and Nutrition Sciences, The University of Queensland;
Alan Pearce, Professor, College of Science, Health, Engineering, La Trobe University;
Kathleen Bachynski, Assistant Professor, Public Health, Muhlenberg College.
Study details
Neuropathologic and Clinical Findings in Young Contact Sport Athletes Exposed to Repetitivev Head Impacts
Ann McKee, Jesse Mez, Bobak Abdolmohammadi, et al.
Published in JAMA Neurology on 28 August 2023.
Abstract
Importance
Young contact sport athletes may be at risk for long-term neuropathologic disorders, including chronic traumatic encephalopathy (CTE).
Objective
To characterise the neuropathologic and clinical symptoms of young brain donors who were contact sport athletes.
Design, Setting, and Participants
This case series analyses findings from 152 of 156 brain donors younger than 30 years identified through the Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE) Brain Bank who donated their brains from February 1, 2008, to September 31, 2022. Neuropathologic evaluations, retrospective telephone clinical assessments, and online questionnaires with informants were performed blinded. Data analysis was conducted between August 2021 and June 2023.
Exposures
Repetitive head impacts from contact sports.
Main Outcomes and Measures
Gross and microscopic neuropathologic assessment, including diagnosis of CTE, based on defined diagnostic criteria; and informant-reported athletic history and informant-completed scales that assess cognitive symptoms, mood disturbances, and neurobehavioral dysregulation.
Results
Among the 152 deceased contact sports participants (mean [SD] age, 22.97 [4.31] years; 141 [92.8%] male) included in the study, CTE was diagnosed in 63 (41.4%; median [IQR] age, 26 [24-27] years). Of the 63 brain donors diagnosed with CTE, 60 (95.2%) were diagnosed with mild CTE (stages I or II). Brain donors who had CTE were more likely to be older (mean difference, 3.92 years; 95% CI, 2.74-5.10 years) Of the 63 athletes with CTE, 45 (71.4%) were men who played amateur sports, including American football, ice hockey, soccer, rugby, and wrestling; 1 woman with CTE played collegiate soccer. For those who played football, duration of playing career was significantly longer in those with vs without CTE (mean difference, 2.81 years; 95% CI, 1.15-4.48 years). Athletes with CTE had more ventricular dilatation, cavum septum pellucidum, thalamic notching, and perivascular pigment-laden macrophages in the frontal white matter than those without CTE. Cognitive and neurobehavioral symptoms were frequent among all brain donors. Suicide was the most common cause of death, followed by unintentional overdose; there were no differences in cause of death or clinical symptoms based on CTE status.
Conclusions and Relevance
This case series found that young brain donors exposed to repetitive head impacts were highly symptomatic regardless of CTE status, and the causes of symptoms in this sample are likely multifactorial. Future studies that include young brain donors unexposed to repetitive head impacts are needed to clarify the association among exposure, white matter and microvascular pathologic findings, CTE, and clinical symptoms.
See more from MedicalBrief archives:
Landmark US health body decision on collision sports link to CTE
Neuro-degeneration found in Australian athletes playing codes at risk of head injury
All Blacks star joins international class action following early onset dementia diagnosis