Medical News Today: Concussion leaves mark in brain's white matter 6 months after injury

Breaking research shows changes in white matter function 6 months after a head injury.

In short, a concussion is a brain injury that changes the way the brain functions.

Concussions can happen in a myriad of ways, but contact sports are most commonly to blame.

The Centers for Disease Control and Prevention (CDC) estimate that 1.6-3.8 million concussions occur each year; and, up to 10 percent of athletes suffer a concussion in any given sports season.

The primary effects of a concussion include thinking (cognitive) problems, headaches, and issues with balance; these are normally temporary problems.

However, as researchers investigate this type of injury more thoroughly, using new brain imaging techniques, longer-term changes are being brought to light.

The long-term effects of concussion

The most recent study to investigate the longer-term effects of concussion will be presented at the Sports Concussion Conference in Chicago, IL, July 8-10. The conference is being hosted by the American Academy of Neurology, who are leaders in the field of sports-related concussions.

The study was headed up by Melissa Lancaster, Ph.D., at the Medical College of Wisconsin in Milwaukee; the team examined 17 high school and college football players, all of whom had sustained a sports-related concussion.

Each participant received an MRI scan, their concussion symptoms were rated, and other parameters – such as cognitive deficits, balance problems, and issues with memory – were also recorded.

The scans and assessments were carried out after 24 hours, 6 days, and 6 months following the trauma. The results of these assessments were compared with 18 matched athletes who had not sustained a head injury.

The participants were given advanced brain scans – diffusion tensor imaging and diffusion kurtosis tensor imaging. These exams checked for short- and long-term changes in the functioning of the brain’s white matter.

White matter changes

White matter is so called because, as the name suggests, it is lighter in color than the gray matter that surrounds it. Initially considered to be a relatively passive and unimportant part of the brain, white matter is now known to play a vital role in brain function and learning.

Gray matter can be thought of as the processing and cognition center, while white matter acts as a relay station, communicating between different areas. Its tracts and projections make up the bulk of the deep regions of the brain. In fact, white matter makes up around 60 percent of the brain’s volume.

Tensor imaging is a relatively new imaging technique; it measures how water moves (diffuses) through brain tissue and charts changes in the way that information passes between regions of the brain through white matter tracts.

White matter and concussion

The scans showed that the concussed athletes had a reduction in water diffusion throughout the white matter at the 24-hour and 6-day markers, compared with athletes who had not sustained a head injury.

These alterations in the brain’s microstructure persisted 6 months later. The athletes who had experienced the most severe symptoms following the concussion were the most likely to display white matter anomalies at the 6-month mark.

Despite the persistent changes seen in the scans in the 6-month tests, there were no differences between the injured and non-injured athletes’ self-reported concussion symptoms, balance, or cognition.

“In other words, athletes may still experience long-term brain changes even after they feel they have recovered from the injury. These findings have important implications for managing concussions and determining recovery in athletes who have experienced a sports-related concussion.”

Melissa Lancaster, study author

Of course, further study is necessary to understand what these changes mean and how they relate to long-term health outcomes. But, due to the prevalent nature of head injuries in sports, follow-up research is likely to come hot on this study’s heels.

Learn more about medical advances in treating head injuries.