CTE & Young Athletes

Date: August 28, 2023

Signed by: Ann C. McKee, MD (Corresponding Author)

Executive Summary

This research article, published in JAMA Neurology, presents findings from 152 brain donations of contact sport athletes under 30 years old who were exposed to repetitive head impacts (RHIs). Conducted through the Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE) Brain Bank, the study aimed to assess the presence and effects of chronic traumatic encephalopathy (CTE) and other neuropathological changes. CTE was found in 41.4% of donors, the majority in mild stages (I or II). Despite high symptom reports across all donors, the presence of CTE was not directly associated with symptom severity. The study concludes that symptoms in this population are likely due to a combination of CTE and other factors, emphasizing the need for further research including individuals not exposed to RHIs.

Key Provisions

Study Design and Participants (Methods)

Case series involving 152 of 156 brain donors under age 30 with a history of contact sports and RHIs.
Brains donated between February 1, 2008, and September 31, 2022.
Clinical data collected through interviews and questionnaires with informants (pg. 1037, para. 3).

Neuropathologic Diagnosis Criteria

CTE diagnosis based on National Institute of Neurological Disorders and Stroke (NINDS) criteria.
CTE was categorized into stages I through IV using the McKee staging system (pg. 1039, para. 2).
CTE was present in 63 out of 152 donors (41.4%); 60 had mild (stage I or II) and 3 had stage III CTE.
No cases of stage IV CTE were found (pg. 1039, para. 2).
McKee CTE Stages:

Stage I (Mild): Isolated focal accumulation of tau in the cerebral cortex with minimal brain atrophy. Symptoms may include very minimal and mild headaches, attention problems, and confusion.
Stage II (Mild to Moderate): Tau pathology in multiple cortical area, light atrophy of the frontal cortex and enlargement of the ventricles. Symptoms may include, mood swings, depression, short-term memory loss.
Stage III (Moderate): Widespread tau deposits in the frontal and temporal lobes. Hippocampus, amygdala, and thalamus begin to show signs of degeneration.
Stage IV (Severe): Extensive tau pathology throughout the cerebral cortex, brainstem, and white matter and marked brain atrophy, ventricular enlargement, shrinkage of the hippocampus. Profound cognitive decline and dementia, severe memory loss and language difficulties

Sports Participation and CTE Association

Most with CTE had played American football (76.2%).
CTE was also found among ice hockey players, soccer players, rugby players, and wrestlers.
Longer duration of football play was linked to CTE presence (pg. 1040, para. 2-4).

Pathologic Brain Features in CTE Cases

Frequent signs included:

cavum septum pellucidum: A small, fluid-filled space in the middle of the brain between two thin walls. If it stays open in adults, it can be a sign of brain injury or conditions like CTE.
ventricular enlargement: The ventricles are open spaces in the brain that hold fluid. When they enlarge, it can mean the brain around them is shrinking.
thalamic notching: The thalamus is a part deep in your brain that acts like a relay station for messages going to different parts of your brain. Notching means it has little dents or damage in it.

Increased white matter damage and pigment-laden macrophages in frontal brain regions (pg. 1042, Table 2).

Microscopic and Immunopathologic Markers

CTE lesions mainly found in frontal, temporal, and parietal cortices.
Tau pathology predominantly involved 4-repeat tau protein in neurons, with no astrocytic tau observed (pg. 1043, para. 2).

Translation: They found that a harmful protein called tau was building up inside brain cells called neurons.

Clinical Symptoms Reported

Symptoms of cognitive difficulty, mood changes, and behavioral issues were common across all donors.
No statistically significant symptom differences between those with and without CTE (pg. 1043, para. 4-5).

Substance Use and Mental Health Indicators

High prevalence of substance use and psychological symptoms, including impulsivity, apathy, and depression.
Suicide was the most common cause of death (pg. 1043-1044, Table 1).

CTE in Female Athletes

One female collegiate soccer player was diagnosed with stage I CTE.
Female donors overall had fewer years of exposure to RHIs (pg. 1040, para. 5-6).

Limitations of the Study

Non-random, convenience sample with potential selection bias.
Lack of a comparison group unexposed to RHIs or representative of the general population (pg. 1046, para. 6).

Conclusion

Young athletes exposed to RHIs may develop early-stage CTE, but symptoms can arise from multiple causes.
Further research with non-exposed control groups is necessary to isolate the effects of RHIs and CTE (pg. 1047, para. 1).

Source: Neuropathologic and Clinical Findings in Young Contact Sport Athletes Exposed to Repetitive Head Impacts

CTE & Young Athletes