Understanding Concussions

Emerging research reveals the lasting effects of concussions and traumatic brain injuries (TBIs). 

The issue received unprecedented attention after former NFL players who sustained numerous concussions during their careers reported a higher rate of depression, dementia, and other mental health problems than non-players.

Concussions are fairly common. In 2009, an estimated 2.4 million people in the U.S. had a mild brain injury of some kind.

A new study in the journal Neurology involving 80 concussion-free Division I NCAA Dartmouth College varsity football and ice hockey players shows that even without concussions, enough damage to the brain’s white matter can have an effect on test scores, learning, and memory.

Now, research from the National Institutes of Health is pinpointing exactly what happens when the brain is injured and how long its effects can last.

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What Happens During a Concussion

Lawrence Latour, a scientist at the Center for Neuroscience and Regenerative Medicine in Bethesda, Md., studied people who had recently suffered a concussion but didn’t appear to have any physical damage to their brain tissue. Using a contrast dye during MRI scans, Latour and his team saw the chemical leaking into the meninges—the protective outer membranes covering the brain—in half of 142 patients with a concussion.

The researchers developed a mouse model to study trauma to the meniges and observe how damage spreads into the brain over time. They found that the skull bone, even if it wasn't damaged, was porous enough to allow small molecules to enter the brain. Their research was published in the journal Nature.

“It was surprising to discover that all these protective barriers the brain has may not be concrete. You can get something to pass through them,” senior author Dorian McGavern, a scientist at the National Institute of Neurological Disorders and Stroke, said in a press release.

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A Window for Treatment

Under a powerful microscope, researchers watched what happened to mouse brains after a concussion. They found that cell death can create holes in the glial limitans, the brain’s last defense against dangerous molecules. But cell death in the underlying brain tissue did not occur until nine to 12 hours after the injury.

While other studies have found that the body’s immune response after an injury can actually cause more damage to the brain, McGavern’s research suggests that this response during a mild brain injury may protect brain tissue for up to 12 hours after the initial trauma.

And there’s another silver lining: researchers found that applying glutathione—an antioxidant that is normally found in our cells—directly to the skull surface after brain injury reduced cell death by 67 percent, and by 51 percent when applied three hours after injury.

“This idea that we have a time window within which to work, potentially up to three hours, is exciting and may be clinically important,” McGavern said.

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