The brain damage associated with concussion may be caused by repetitive impacts, as opposed to single events, research conducted by scientists at Trinity College Dublin indicates.
The authors say their work marks a significant advance in the understanding of mild head trauma, or concussive brain injury, and how it may be managed and treated in the future.
Rugby players and mixed martial arts fighters were recruited to take part in the four-year clinical research study, which is continuing.
While concussive injuries are of increasing concern within sports involving collision or combat, they are also a very common injury in children and young adults. They also represent a big challenge to doctors due to the lack of any strong biomarkers or ways of imaging the injury.
"This was a hypothesis-driven project whereby we challenged the hypothesis that repetitive head trauma would induce damage to small blood vessels in the brain that we would then be able to image with a novel form of MRI-based brain scans," said Dr Matthew Campbell, assistant professor at Trinity's institute of neurosciences.
‘Leaky’ blood vessels
The study used both sensor-enabled mouthguard technology and dynamic contrast-enhanced MRI to confirm the number and severity of head impacts that would lead to the appearance of “leaky” blood vessels within the brain.
While concussive brain injuries cause clinical symptoms such as dizziness, nausea and confusion, these symptoms all occur independently of any adverse findings on scans, or without the presence of any clear blood-based biomarkers.
"Our findings suggest for the first time 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," said Dr Colin Doherty, consultant neurologist at St James's Hospital and clinical lead on the study. "It appears the repetitive nature of these impacts as opposed to single events is causing damage to the capillaries of the brain."
The study, published in Journal of Neurotrauma, found 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 MRI-based imaging.
The authors say their findings could pave the way for better guidelines on players returning to play, and improved player safety, in the longer term.
