Research suggests traumatic brain injury recovery may be influenced by gene

By Claire Hettinger

University research suggests that one gene in particular plays a role in how well a person recovers from a traumatic brain injury.

Aron Barbey, study leader and professor of speech and hearing science, psychology and neuroscience, explained that patients with different variations of the brain-derived neurotrophic factor gene react differently to brain injury.

The variants involve a change in either the valine or methionine amino acids in this gene. The gene combinations are either Met/Met, Met/Val or Val/Val, depending on which genes were received from parents.

“What our findings indicate is that if an individual has the Val/Val combination then their performance on a battery of cognitive tests was remarkably lower than that of individuals who had the Val/Met or Met/Met combination,” he said.

This research found a molecular genetic marker predicting cognitive outcome following a brain injury. It shows that patients with certain genes will react to injuries in certain ways, and it predicts their recovery, Barbey said.

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The participants of the study were found on the Vietnam Head Injury Study registry, which includes American male veterans who all suffered brain damage from penetrating head injuries during the Vietnam War. These veterans did not show any difference in general intelligence prior to their brain injury.

After their injury however, those with the Val/Val gene variant scored an average of eight points lower on general intelligence tests.

The brain-derived neurotrophic factor gene is involved with the growth factor and the production of new neurons in the brain, Barbey said. The study also considered the relationship between the gene variation and the preservation of general intelligence after a traumatic brain injury. General intelligence is measured by standardized tests of intelligence including verbal comprehension, perceptual organization, working memory and processing speed.

Barbey said the research team was interested in understanding how individuals recover from traumatic brain injury because little is currently known. They wanted to study individuals with previous brain injuries and identify specific principles that predict recovery or continued problems following traumatic brain injury.

Jim Monti, postdoctoral research associate at Beckman Institute, said there are three levels of traumatic brain injury — mild, moderate and severe. These are classified by how long a person is unconscious — mild being zero to 30 minutes, moderate 30 minutes to 24 hours and severe more than 24 hours, he said.

He said brain injuries can occur when any force acting on the body “causes the brain to rapidly accelerate and decelerate.” He explained that these injuries can come from many situations ranging from a person falling and hitting their head, to the whiplash of a car accident or a bomb going off near a person.

“There is definitely growing interest on our campus in doing (traumatic brain injury) research,” said Rachael Rubin, postdoctoral research associate at Beckman Institute who is involved in traumatic brain injury research.

She said her research seeks to revamp traumatic brain injury classifications. She said the current system of mild, moderate and severe has been used since the 1970s and is outdated. Things like concussions are considered a mild brain injury, and penetration of the brain is usually considered severe, she said.

“The term ‘mild’ is misleading, because there can actually be pretty severe consequences as a result,” Rubin said.

She said it would be better to characterize a range of brain injuries to better understand what impairments a patient has at neurological and behavioral levels.

“It is a challenge developing treatments and therapies for traumatic brain injury just because there are so many different kinds of traumatic brain injuries that we are not always sure what the underlying cause is,” she said.

If the specific variant of the brain-derived neurotrophic factor gene is known, then treatment can be tailored to fit the needs of the individual, Barbey said. A patient with the Val/Val combination, as the study found, is more likely to need treatment focused on their cognitive functioning ability.

“We want to understand … what principles predict the kind of cognitive impairments an individual might have following a brain injury and the time course of those impairments, like how long and to what extent can individuals recover over time,” Barbey said.

He said patients may be tested in the future following a brain injury to see which gene variant they have and that this information may help guide clinical therapy and identify a specific treatment approach that is tailored to the needs of the patient.

“These findings also emphasize the importance of a multidisciplinary approach to understanding traumatic brain injury that incorporates neuroscience, psychology, molecular genetics, and medicine — to understand the mechanisms and treatment approaches that make recovery from traumatic brain injury possible,” Barbey said in an email.

Claire can be reached at [email protected].