A new study shows that participation in elite adult rugby may be associated with changes in brain structure. The research was published today (22 July 2021) in Brain Communications, by senior author Prof David Sharp, Centre Director of UK DRI Care Research & Technology, and colleagues at Imperial and UCL.

The study included 44 elite rugby players, almost half of whom had recently sustained a mild head injury while playing.

The research - called The Drake Rugby Biomarker Study - found a significant proportion of the rugby players had signs of damage to the white matter, in addition to abnormal changes in white matter volume over time.

White matter is the ‘wiring’ of the brain, and helps brain cells communicate with each other. The research team say more work is now needed to investigate the long-term effects of professional rugby on brain health.

Prof David Sharp, UK DRI Centre Director, said: “Despite relatively high rates of head injury and an increasing focus on prevention, there has been relatively little research investigating the long-term effects of rugby participation. Previous work in retired rugby players have found evidence of higher self-reported rates of depression and mild cognitive impairment compared to non-rugby players. However, the causes of these problems are unclear.

Lauren Pulling, The Drake Foundation’s CEO, said: “The Drake Foundation would like to thank the RFU, rugby clubs and research team for their support in this vital study. At present, the long-term consequences of these brain structure abnormalities are unknown and require further research. However, taken together with existing evidence across different sports, as well as recent cases of rugby players being diagnosed with brain diseases in their 40s, they are painting a concerning picture when it comes to players’ long-term brain health.”

The study, which took place between July 2017 and September 2019, assessed 41 male players, and three female.

All underwent a type of brain scan called an MRI, and around half then had a second MRI scan a year later. The study used two advanced types of MRI called susceptibility weighted imaging and diffusion tensor imaging. This allowed them to look at the structure of blood vessels and the white matter. The study is the first to assess long-term changes in MRI images of professional rugby players.

The rugby players were compared to athletes in non-collision sports, as well as individuals who were not athletes.

Among the group of rugby players, 21 were assessed shortly after sustaining a mild head injury, called a mild traumatic brain injury. In professional rugby union in England, these types of head injuries, which often cause concussions, are the most common reported match injury – accounting for one in five injuries.

The scientists analysed the brain scans for changes in the white matter of the brain, and compared these to the athletes in non-collision sports, and the non-athletes.

The results revealed that 23 percent of all of the rugby players showed damage to their cell axons (the ‘wires’ of brain cells), or small tears in blood vessels. These tears cause small leaks in the brain, called microbleeds.

These changes were seen in both players with and without a recent head injury.

In addition, the scans provide evidence for unexpected changes in white matter volume across the whole group of rugby players. These could indicate a longer-term effect of damage to connections in the brain. However, further research is needed to understand the significance of these changes in brain structure.

The research team also asked the players to complete assessments, such as memory tests, to analyse their brain function. The results revealed players with abnormalities in their brain structures did not perform worse than players without abnormalities.

The study team add that long-term studies are needed to investigate the long-term effects on brain health. They add that other health benefits of sports participation must also be taken into account when assessing impact on the brain health.

Mr Karl Zimmerman, lead author from Imperial’s Department of Brain Sciences, said: “The implications on an individual level of the brain changes associated with elite rugby participation are unclear, although obviously it is concerning to see these changes in some of the players’ brains. It is important to note that our results in adult professional rugby union and league players are not directly comparable to those who play at local or youth levels. The overall health benefit of participating in sports and physical exercise have been well established including the reduction in mortality and chronic diseases such as dementia. Long-term studies are now needed of both active and retired rugby players to investigate the effect of participation on long-term brain health.”

Dr Simon Kemp, Medical Services Director at the Rugby Football Union added: “The RFU is fully committed to advancing our understanding of the short, medium and long term consequences of head impacts and concussions so that we can ensure we can make continued improvements in player welfare. We welcome any research that helps to advance our knowledge which is why we actively collaborated with the academic institutions on this research project from its inception, particularly to promote the recruitment of players. As the science evolves, so too does our focus around player welfare and head impact prevention and management. While it is unclear from this research what the individual long-term implications are regarding the brain changes seen, it is clearly critically important to investigate this further. To further develop this understanding, the RFU, in partnership with Premiership Rugby and independent experts, will be providing a specialist clinical service for the assessment and management of retired elite male and female rugby players between the ages of 35-50 to individually assess their brain health. An integrated and parallel research programme will review the risk, causes, assessment and management of brain problems for those who have participated in elite rugby.”

The work was funded by The Drake Foundation, who brought together academia and sport for this pioneering study, and was supported by the NIHR Imperial Biomedical Research Centre, the UK Dementia Research Institute and the Rugby Football Union.

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Article published: 22 July 2021

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Professional rugby may be associated with changes in brain structure