A landmark international study has identified a link between Rugby Union career length and the risk of the degenerative brain condition chronic traumatic encephalopathy (CTE).

In a world-first collaboration between leading laboratories at the University of Glasgow, Boston University and the University of Sydney, researchers find new evidence to link playing rugby – either at amateur or an elite level – with risk of developing CTE. Led by Prof Willie Stewart at the University of Glasgow, the work follows major findings from his group last year which reported neurodegenerative disease risk among former Scottish international rugby union players approximately two and a half times higher than expected.

CTE is a degenerative brain condition which has been shown to be, at least in part, a result of exposure to repeated head impacts and head injuries. Over the past decade or so, there have been increasing reports of the unique pathology of CTE following postmortem examination of the brains of former contact sports participants, including football, American football, boxing and rugby.

This latest study, which is published in Acta Neuropathologica, looked at the results of detailed postmortem brain examinations of 31 former amateur and elite rugby union players whose brains were donated for research purposes to one of three leading centres in the UK, United States, and Australia. CTE was found in around two thirds (68%) of the brains examined, and in both amateur and elite players.

Importantly, risk of CTE pathology was associated with length of a player’s rugby career, with each additional year of play adding 14% to risk of CTE. Player position or level of participation, either amateur or elite, did not appear to influence risk of CTE.

The current study, which is the first research collaboration between these leading international research groups, is a continuation of the University of Glasgow’s ground-breaking research into brain health outcomes associated with traumatic brain injury and contact sports.

Among sports, rugby union is known to have a high risk of mild traumatic brain injury (concussion), with injury rates highest in the professional game. To date, the only recognised risk factor for CTE is traumatic brain injury and repeated head impact exposure.

Professor Willie Stewart, consultant neuropathologist and Honorary Professor at the University of Glasgow, lead author of the study, said: “In this study, we have combined the experience and expertise of three leading international brain banks to look at CTE in former rugby players."

“These results provide new evidence regarding the association between rugby union participation and CTE. Specifically, our data show risk is linked to length of rugby career, with every extra year of play increasing risk. Based on this it is imperative that the sport's regulators reduce exposure to repeated head impacts in match play and in training to reduce risk of this otherwise preventable contact sport related neurodegenerative disease.”

In this latest study, the average rugby career length was around 18 years, with an equal number of forward and backs. Twenty-three (74%) played rugby exclusively as amateurs, with 8 (26%) reaching elite level, either as professional or representative internationalists.

Ann McKee, MD, director of the BU CTE Center and UNITE brain bank, and co-author of the study, said: “CTE is a preventable disease; there is an urgent need to reduce not only the number of head impacts, but the strength of those impacts, in rugby as well as the other contact sports, in order to protect and prevent CTE in these players.”

The director of the Australian Sports Brain Bank, Associate Professor Michael Buckland, points to the conclusions drawn by the Australian Senate Inquiry into Concussions and repeated head trauma in contact sports. He said: “The findings of the recent federal government inquiry are unambiguous: there is clear evidence of a causal link between repeated head trauma and concussions and subsequent neurodegenerative disease such as CTE. Sports regulators need to develop and implement CTE risk minimisation protocols as a matter of urgency.”

Brain autopsies for the study were accessed from three international sites: the Understanding Neurologic Injury and Traumatic Encephalopathy Brain Bank (UNITE), Boston University School of Medicine, the Glasgow TBI Archive (GTBI), University of Glasgow and the Australian Sports Brain Bank (ASBB), Royal Prince Alfred Hospital and University of Sydney, Australia.

The paper, ‘Risk of chronic traumatic encephalopathy in rugby union is associated with length of playing career’ is published in Acta Neuropathologica. The work was funded by National Institute of Neurological Disorders and Stroke of the National Institutes of Health, the National Institute on Aging, the US Department of Veterans Affairs, The Concussion Legacy Foundation, Nick and Lynn Buoniconti Foundation, Andlinger Foundation, and an NHS Research Scotland Career Researcher Fellowship. The ASBB is supported by Sydney Local Health District and unrestricted philanthropic donations.