The story of chronic traumatic encephalopathy is not as simple as it seems

McKee AC, Mez J, Abdulmohammad B, et al. JAMA Neurology. Published online 2023. doi:10.1001/jamaneurol.2023.2907
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Take home message

Less than half of young adults exposed to repetitive head impacts through sports and who suffered from mental health and cognitive disorders before death met clinical criteria for a diagnosis of chronic traumatic encephalopathy (CTE). Other factors may contribute to CTE-like symptoms in this group.

Background

The sports community is increasingly concerned about the long-term consequences of repetitive head impacts (e.g. CTE). CTE can cause cognitive impairment, mental health problems and mood disorders. Very few studies have examined the presence of CTE in a large group of young adults, which could provide insight into CTE in former youth athletes without other age-related brain changes.

Study aim

The authors sought to understand the pathological brain changes and symptoms of former contact athletes under the age of 30 at death.

Methods

The authors used donated brains from 152 young individuals (13 to 29 years) with a known history of repeated head impacts. These brains come from the Brain Bank Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE). Researchers contacted next of kin to conduct cognitive and mental health assessments of the donor. A team of four neuropathologists diagnosed CTE or other neurodegenerative diseases based on established evaluation criteria.

Results

Overall, based on the 152 brain samples, 41% of donors had CTE. Of these, all but three brains had only mild CTE. Older donors and former American football athletes with a longer history of participation in contact sports were more likely to develop CTE. Clinical cognitive and mental health problems were common among participants regardless of CTE diagnosis.

Viewpoints

The authors found that ~41% of people under the age of 30 with a history of contact sports and cognitive and mental health problems have CTE. Thus, for individuals under age 30 at death, their cognitive and mental health problems may be caused by something other than CTE (e.g., life stressors, genetics, and other underlying mental health problems). It is important to avoid applying these findings to the broader athletic population because most, if not all, brains were donated due to observed pathology before death. Additionally, this study group was predominantly male (93%) and white (73%), further limiting interpretation.

Clinical implications

In practice, this research suggests that CTE may be just one of many causes of cognitive and mental health problems after exposure to repetitive head impacts through sports. As a result, physicians must be prepared to support patients with mental health needs and promote timely referral to mental health professionals for further care. We must also educate our patients that not all cognitive and mental health problems in athletes are due to CTE and that it remains unknown how many people have CTE among those with or without a history of sports participation.

Questions for discussion

What other factors may contribute to CTE-like symptoms in former contact athletes? What experiences have you had with former/current athletes suffering from CTE or CTE-like symptoms?

related posts

1. Few definitive CTE cases have been detected with and without history of brain injury and collision sports
2. Most military service members don’t have to worry about CTE
3. Treatable conditions should be explored in former athletes with CTE-like symptoms

Written by Cade Watts
Reviewed by Jeffrey Driban