The risk of CTE increases by 14% per year of rugby play, even in amateurs
By Melissa Brown. This article was initially published in the 2/1/24 edition of our Concussion Update newsletter; please consider subscribing.
In October 2023, Willie Stewart et al. published a paper in Acta Neuropathologica demonstrating an association between the development of CTE and the length of a person’s rugby career. In this retrospective study, researchers analyzed brain autopsies from three international brain banks, including those at the Boston University School of Medicine (UNITE), the Glasgow TBI Archive, and the Australian Sports Brain Bank in Sydney. Of the 32 brains, 21 brains (68%) showed a range of severities of CTE. When Stewart and the team adjusted for a number of factors, they found a dose-response relationship between rugby career length and severity of CTE presentation, with risk increasing by 14% per year of play. Additionally, 23 brains (74%) were from individuals who only ever played amateur rugby. The authors note that “in respect of CTE, at least, our data suggest that level of participation does not protect against development of this neurodegenerative pathology.”
These authors note a limitation in sampling. In particular, only brains donated to these banks were used, making selection bias a possible factor; brains donated are often from individuals whose families were concerned that the individual’s symptoms might indicate CTE. Also, only one of the 31 brains was female, and most of the donated brains were amateur players. Generally, study conclusions, such as the dose-response effect of increasing CTE risk per year of play, should only be applied to the sample analyzed. However, the authors reference a 2023 study finding professional athletes to have increased risk for neurological diseases (e.g., ALS and dementia) with no such association in amateurs, thus contextualizing their findings (particularly those pertaining to amateur players) into the broader picture of the relationship between neurodegeneration and contact sports history.
This study adds to growing evidence that playing contact sports increases players’ risk for developing neurodegenerative disease and, independently, CTE pathology. Previous studies demonstrate a significantly greater risk of concussion in rugby players compared to other contact sports like American Football, ice hockey, and wrestling. Also, Over the past 20 years, the risk for concussions at the professional level has been increasing. However, a recent study by the Boston CTE center found that repetitive subconcussive hits contributed to the risk of CTE and that concussions were not a significant risk factor for CTE. Stewart’s team had similar findings, as they write, “While history of TBI with loss of consciousness and/or concussion was common among cases with CTE, this was not significantly different to prevalence among cases without CTE.” This current study by Stewart et al. signifies a need greater than ever to develop safety precautions and protocols for players at all levels.