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Participation in elite rugby may affect brain structure

Researchers assessing long-term changes in the brain in professional rugby players found almost half showed an unexpected reduction in brain volume and nearly a quarter displayed abnormalities in brain structure.

Research supported by the NIHR Imperial Biomedical Research Centre assessed long-term changes shown in the brain scans of 44 professional adult players. Almost half of the group were assessed shortly after sustaining a mild head injury. 

All the players underwent an MRI, and around half then had a second MRI scan a year later, the first time long-term changes in MRI images of professional rugby players have been assessed. The study used two advanced types of MRI called susceptibility weighted imaging and diffusion tensor imaging, allowing the researchers to look at the structure of blood vessels and the white matter. 

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

The results, published in the journal Brain Communications, also 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. Changes were seen in both players with and without a recent head injury.  

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.

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.

Further long term research is needed to understand the significance of these changes in brain structure. The study team underlined that other health benefits of sports participation must also be taken into account when assessing impact on brain health.

Professor David Sharp, senior author from Imperial’s Department of Brain Science and NIHR Research Professor, said:

“Our research using advanced MRI suggests that professional rugby participation can be associated with structural changes in the brain that may be missed using conventional brain scans. What is not clear at this stage is the long-term clinical impact of these changes.

“Further research is needed to understand the long-term implications of repeated head injuries experienced during a rugby career and to provide more accurate ways to assess risk for an individual.”

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.”