Does football cause dementia? Those who have seen the movie “Concussion” starring Will Smith or heard about chronic traumatic encephalopathy (CTE) in the media may wonder if playing football is damaging to the brain. First observed in boxers and named “dementia pugilistica,” CTE is a controversial diagnosis, but evidence in favor of this disease is growing. The truth may have major ramifications for powerful organizations such as the NFL and American sports culture as we know it.
In 2013, McKee et al. published a study in Brain which analyzed the post-mortem brains of 85 subjects with histories of repetitive mild traumatic brain injury. In 68 of these brains, they found evidence of CTE, seen on pathology as a unique deposition pattern of neurofibrillary tangles, a biochemical maker of dementia. The majority of these patients were athletes, and their brains were compared to age-matched controls who did not have history of repetitive brain injury. The amount of neurofibrillary tangles varied and was classified into different stages (I-IV). Patients in stage I had experienced mild concussive symptoms like headache and loss of attention, while stage IV subjects had experienced advanced dementia. The authors also found evidence of axonal loss in the white matter in all of these brains, suggesting damaging of connectivity between different brain regions. The stage of CTE correlated with increased duration of football play. This group went on to publish a study in JAMA of 202 brains of American football players, of which 177 showed signs of CTE. The authors acknowledge the role of selection bias in this study as the brains were from a brain bank, and many of the families donating brains may have been motivated by clinical signs of dementia they had noticed in the participant. Nonetheless, the body of evidence in favor of CTE cannot be ignored and warrants larger studies.
Despite McKee et al.’s characterization of CTE as a disease entity with different stages, however, not all neuroscientists accept this diagnosis. Neuropsychologist Christopher Randolph argued in 2018 in the Archives of Clinical Neuropsychology that the evidence is not strong enough to call CTE a true disease. He acknowledges that while the brains in the previously described study show a specific pattern of p-tau deposition, this may not necessarily correlate consistently with clinical symptoms of dementia. Another study at SUNY Buffalo found no increased rate of dementia in a study of 21 ex-professional football and hockey players compared to players of non-contact sports. However, there was some concern of conflict of interest because this study was funded by the Buffalo Bills football team owner.
Where do these studies leave us? So far, the NFL and other major contact sports leagues have made a few changes to mitigate risk of CTE. For example, the NFL has banned players from initiating contact with the crown of their helmet. Nonetheless, some argue that the NFL is using tactics similar to those of tobacco industries to shut down claims about the dangers of their sport. Football is clearly an important part of American culture, but the potential risks of dementia should not be ignored. Larger studies that minimize selection bias would be informative, and the influence of NFL funding on outcomes should be considered. Even if CTE is an undeniable risk of contact sports, however, this doesn’t necessarily mean we need to ban football entirely. At the very least, people considering going into the sport should be well-informed about risks, and investment should be made into more protective equipment and safety rules.
1. Chen, I. (2020, February 1). Exactly How Dangerous Is Football? The New Yorker. Retrieved from https://www.newyorker.com/culture/annals-of-inquiry/exactly-how-dangerous-is-football
2. McKee, A.C., Stein, T.D., Nowinski, C.J., Stern, R.A., Daneshvar, D.H., Alvarez, V.E., et al., 2013 Jan 1. The spectrum of disease in chronic traumatic encephalopathy. Brain 136 (1), 43–64.
3. Mez J, Daneshvar DH, Kiernan PT, et al. Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football. JAMA. 2017;318(4):360–370. doi:10.1001/jama.2017.8334
4. Randolph, C. (2018). Chronic traumatic encephalopathy is not a real disease. Archives of Clinical Neuropsychology, 33(5), 644–648. doi: 10.1093/arclin/acy063
5. Willer, B. S., Zivadinov, R., Haider, M. N., Miecznikowski, J. C., & Leddy, J. J. (2018). A Preliminary Study of Early-Onset Dementia of Former Professional Football and Hockey Players. Journal of Head Trauma Rehabilitation, 33(5). doi: 10.1097/htr.0000000000000421
Natalie Neale is a graduate of the Perelman School of Medicine. Natalie can be reached by email at [email protected].
