REPETITIVE IMPACTS – AS opposed to single events – are key to understanding concussive brain injuries in sports such as MMA and rugby, according to scientists at Trinity College Dublin. 

Mild head trauma has come to the fore in recent years as being associated with collision and combat sports such as MMA and rugby, the researchers noted. 

However, it is also a very common injury in children and young adults. This represents a significant challenge to doctors due to the lack of any robust biomarkers or objective imaging approaches to manage the injury, they said. 

The study, which was undertaken by the Trinity-led concussion research interest group, used both sensor-enabled mouthguard technology and dynamic contrast-enhanced MRI.

These were used to confirm the number and severity of head impacts that would result in the the appearance of “leaky” blood vessels within the brain. 

Participants of combat and collision sports such as mixed martial arts (MMA) and rugby took part in the study, which took four years to complete.

The researchers noted that while it is clear that concussive brain injuries cause clinical symptoms such as dizziness, nausea and confusion, these symptoms all happen independent of any adverse findings on CT or MRI scans, and without the presence of any clear blood-based biomarkers. 

Therefore, it can prove challenging to clinically manage concussive brain injuries, they said.

“Our findings for the first time suggest that repetitive head trauma can lead to an MRI signal that we can definitively link to the number and severity of impacts to the head,” study lead Dr Colin Doherty said. 

“It appears that the repetitive nature of these impacts as opposed to single events are causing damage to the capillaries of the brain,” he said.

The study reports that repetitive impacts to the head, not necessarily just concussions, are likely able to induce changes to the micro-vessels of the brain. 

It is these changes that are then readily visible when using a regular form of MRI-based images. 

While the study was based on a selected group of MMA fighters and rugby players, the findings could eventually pave the way for more robust and objective return-to-play guidelines and improved player safety in the longer term, the researchers noted. 

“This study has highlighted the critical importance of continued efforts to study the underlying effects of concussive brain injuries in all sports,” co-author Professor Mick Molloy said.

“It is imperative that the governing bodies take note of these findings and work together to protect athletes now and in the future.” 

The research has been published in the Journal of Neurotrauma.