Mounting evidence has suggested a linkage between American football and chronic traumatic encephalopathy (CTE). Recently, a study examining the deaths of 111 National Football League (NFL) players found an overwhelming 110 CTE cases. CTE is a neurodegenerative disease associated with repeated blows to the head. Normally, tau proteins in the brain provide a scaffold for neurons, but repeated head trauma causes hyperphosphorylation of these proteins, which then aggregate to form neurofibrillary tangles (NFTs). NFTs can progressively spread throughout the brain over many years and disrupt function in critical regions, such as the hippocampus (responsible for memory and emotion), the amygdala (aggression), and the frontal cortex (cognition and executive functions). As a result, CTE symptoms include memory loss, aggression, and suicidal behaviour.
Although CTE is well-known for its presence in high-profile NFL players, like the late Aaron Hernandez, a two-year study on high school football players suggests that CTE-associated pathology can be found in young, amateur athletes as well. Given that more than 1.1 million high school athletes play football in the United States, the impact of CTE may be more widespread than commonly assumed. Moreover, a recent study published in Nature suggests that playing football from a young age can result in more severe long-term symptoms of CTE. Specifically, the investigators noted that athletes who began playing before age 12, in comparison to those who started at or after this age, faced triple the odds of depression and more than double the odds of executive dysfunction, as characterized by poor impulse control, working memory, and cognitive flexibility. Nevertheless, studies providing evidence of the link between football and CTE have many limitations, including small sample sizes, and self-selected participants often with greater-than-average concern for their health. Moreover, these studies focus on the correlation, rather than the potential causal relationship, between football and CTE. Such considerations have prompted researchers to recognize the need for prospective, longitudinal studies in validating the causal link between football and CTE.
Research on CTE is an increasingly popular field because of its social impact and widespread applicability. Results from previous studies that linked CTE and football have already facilitated a $1 billion settlement between the NFL and players who suffer from concussion-related diseases. However, a major difficulty facing future studies on CTE is that a definitive diagnosis can only occur through a post-mortem brain autopsy, highlighting the need for research on potential diagnostic tools. A reliable, in-vivo diagnostic method may come from a seven-year, $16 million study conducted by Boston University. The NFL was initially set to fund the study but later backed out amidst accusations that it attempted to direct funding to scientists with previous connections to the league.
Further research on CTE may have implications beyond the football field. Athletes in other injury prone sports, such as hockey and wrestling, are at risk of developing CTE. 20% of the two million American troops deployed to Iraq and Afghanistan are also affected by traumatic brain injuries. Additionally, tau proteins and NFTs are present in other neurodegenerative diseases, including Alzheimer’s disease. Accordingly, diagnostic tools and treatments developed for CTE may lead to breakthroughs for other diseases as well
Written By James Yu
References may be found in the journal.