New research suggests that after a person experiences mild concussion, brain abnormalities are still evident from diffusion tensor imaging brain scans months later, even though most symptoms of concussion have gone. This is according to a study published in the journal Neurology.

Concussion, also know as traumatic brain injury (TBI), is defined as injury to the brain as a result of a hard blow or violent shaking to the head. According to the Centers for Disease Control and Prevention (CDC), around 1.7 million people in the US experience TBI every year.

For their study, the investigators analyzed 100 participants, of which 50 people had suffered a mild concussion, while 50 had not. Both groups were of similar age and education.

The participants were required to carry out memory and thinking skills tests, and symptoms of anxiety and depression were monitored up to 2 weeks after injury. The subjects also had diffusion tensor imaging brain scans.

All tests and scans were repeated up to 4 months after concussion in 26 participants from each group.

Results of the tests revealed that subjects who suffered concussion had more self-reported problems with memory and thinking skills, more physical problems including headaches and dizziness, as well as more symptoms of depression and anxiety 2 weeks after injury, compared with participants who did not have concussion.

When analyzed again 4 months after injury, the researchers found that the symptoms of patients who suffered concussion reduced by 27%.

Damage to gray matter found 4 months after injury

But from the diffusion tensor imaging scans, the investigators found that those who had concussion showed more evidence of abnormalities in the gray matter in the frontal cortex region of both sides of the brain, and these abnormalities could be seen 4 months after concussion.

Andrew R. Mayer, of the Mind Research Network, the University of New Mexico School of Albuquerque and study author, says that cytotoxic edema may explain the brain abnormalities shown in the scans.

This occurs when fluids situated in and around the brain cells experience changes, or if reactive gliosis occurs - the change in the shape of glial cells in the response to damage of the central nervous system.

Researchers say their findings suggest that there are potentially two different recovery modes from brain concussion, with memory, thinking and behavioral symptoms recovering more quickly than psychological brain injuries.

Furthermore, Mayer notes that these results suggest the body may approach healing of concussion in a similar way to recovering from a burn.

He explains:

"During recovery, reported symptoms like pain are greatly reduced before the body is finished healing, when the tissue scabs.

These findings may have important implications about when it is truly safe to resume physical activities that could produce a second concussion, potentially further injuring an already vulnerable brain."

Mayer points out that standard brain scans, such as computed tomography (CT) or magnetic resonance imaging (MRI) would not be able to detect these "subtle changes" in the brain.

"Unfortunately, this can lead to the common misperception that any persistent symptoms are psychological," he adds.

Medical News Today recently reported on a study suggesting that athletes who have suffered concussion may need a break from school after injury.