Study of concussions shows mild ones risky

Even a single concussion appears to cause changes in the structure of the brain that may raise the risk of cognitive problems and depression, a new study has found.

The study, which used magnetic resonance imaging to compare healthy subjects’ brains with those of patients a year after a mild traumatic brain injury, indicated that those with such injuries had shrinkage in brain regions that are key to memory, executive function and mood regulation.

The study, published online in the journal Radiology last week, is the first to show that even a single concussion can leave measurable scars on the brain. It used three-dimensional MRI scanning to measure the brain volume of 28 recent concussion victims and 22 matched controls. A year later, researchers conducted the same scans of 19 patients with mild traumatic brain injuries and 12 people in a healthy control group.

Although the atrophy in the brains of the concussion victims was “global” – it affected the brain’s overall volume – it was particularly pronounced in the anterior cingulate and the precuneal regions. The anterior cingulate appears to serve as a switchboard for connecting the areas of the brain that are crucial to memory, attention, judgment and higher-order reasoning. Altered activity in the precuneus has been linked to depression, anxiety and post-traumatic stress disorder.

“This study confirms what we have long suspected,” said the study’s lead author, Dr. Yvonne W. Lui, neuroradiology chief at New York University’s Langone Medical Center. After a mild traumatic brain injury, “there is true structural injury to the brain, even though we don’t see much on routine clinical imaging,” she said.

That finding could help those who have enduring symptoms after a concussion understand that there are probably “biological underpinnings” that explain their problems, she added.

For all of the increased focus the injury is getting, concussions remain mysterious to physicians: Patients who never lose consciousness may suffer life-threatening crises of bleeding in the brain or have lasting cognitive problems.

Others whose traumatic brain injuries seem severe recover without lingering effects. CT scans, which are most widely used in emergency departments to evaluate concussions, are often poor indicators of the severity of brain injury with head trauma.

A second study, presented at the recent American Academy of Neurology’s annual meeting, suggests that an MRI might be used to detect differences in the post-concussive brain that would lead to better diagnosis and treatment.