Playing American football will likely lead to brain disease, research says

A new study examining the brains of deceased American football players has shown some pretty damning results for current athletes. The researchers were examining the link  playing the sport and contracting chronic traumatic encephalopathy (CTE), a degenerative brain disease often associated with repeated head trauma.

CTE commonly causes symptoms such as memory loss, confusion, depression and dementia. The disease is also often associated with a severely damage amygdala — a part of the brain that helps regulate emotional response, aggression and anxiety.

For the study, neurologists analysed 202 brains — making it the largest of its kind to date. The level, play time and positions of the football players whose brains were used in the study varied, and the numbers are staggering. 87% of the brains were diagnosed with CTE, and 99% of the brains of the former National Football League (NFL) players showed signs of CTE, which can only be diagnosed after death.

The more advanced the player was, the more likely they are to be diagnosed with CTE and the more severe the disease is likely to be. For example, 21% of former high school players were diagnosed with CTE, all having mild pathology. 91% of former college players were diagnosed with the disease, and the majority of former college, semi-professional and professional players had severe pathology.

One important caveat, however: the study’s findings are susceptible to selection bias, since the only brains eligible to use were donated by families specifically because the former player showed signs of CTE. Despite this, it’s hard to argue that these are the results of a sport with no side effects.

The NFL has previously denied a relationship between tackle football and long-term brain disease, until Jeff Miller, the league’s senior vice president of health and safety policy, answered “yes” when asked if there is a link “between football and degenerative brain disorders like CTE” at a roundtable discussion on Capitol Hill in March 2016. He also cited McKee’s previous research, stating that she and her colleagues had diagnosed many players who died with the disease. Several months later, the NFL invested $100 million in support of independent medical research on neuroscience-related topics. One innovative example is a collar for athletes based on the anatomy of woodpeckers, which consistently sustain blows to the head in their line of work.

In a statement released in response to McKee’s new study, the NFL said it supports CTE research, but still pointed to the unknown.

“There are still many unanswered questions relating to the cause, incidence and prevalence of long-term effects of head trauma such as CTE,” it read.

Another one of the study’s findings pointed to its grave importance: suicide was the most common cause of death for the former players whose brains were analysed in the study.

Other published studies list suicide as a clinical feature of the disease, but McKee said more research needs to be done before a correlation is established. 72 of the 202 former players in the study committed suicide, such as Junior Seau — a former NFL linebacker who shot himself in the chest in May 2012.

Substance use disorders and family histories of psychiatric illnesses were also common, occurring in 77 cases. Interestingly enough, there is a significant difference of diagnosis rates between former NFL and Canadian Football League (CFL) players. 88% of the former CFL players brains’ showed signs of CTE, while 99% of NFL players were diagnosed.

The study is limited by factors such as its selection bias and lack of a control group, the researchers write. But the percentages are so shocking and the implications of the disease are so debilitating that it warrants attention.