Even mild traumatic brain injury may cause brain damage, including thinking and memory problems, according to a new study.
For the study, 44 people with a mild traumatic brain injury and nine people with a moderate traumatic brain injury were compared to 33 people with no brain injury.
All of the participants took tests of their thinking and memory skills. At the same time, they had diffusion tensor imaging scans, a type of MRI scan that is more sensitive than traditional MRI for detecting damage to brain cells and helps map fiber tracts that connect brain regions, according to the researchers.
The people with brain injuries had their scans an average of six days after the injury. A year later, 23 of those with injuries had another scan and took the cognitive tests again, the researchers reported.
The study found that compared to the people with no brain injury, those with injuries had damage in brain white matter consisting of disruption to nerve axons, those parts of nerve cells that make up white matter and that allow brain cells to transmit messages to each other.
The study also found that scores on a verbal letter fluency task, a test of thinking, and memory skills, were 25 percent lower in people with a brain injury than in the healthy people. This was strongly related to the imaging measures of white matter damage, the researchers noted.
“Most of the studies thus far have focused on people with severe and chronic traumatic brain injury,” said study author Andrew Blamire, Ph.D., of Newcastle University in the United Kingdom. “We studied patients who had suffered clinically mild injuries, often from common accidents, such as falling from a bicycle, or slow speed car accidents.
“This finding is especially important, as 90 percent of all traumatic brain injuries are mild to moderate.”
One year after the injury, the scores on thinking and memory tests were the same for people with brain injuries and those with no injuries, the researchers noted. However, the researchers found that there were still areas of brain damage in people with injuries.
“These results show that thinking skills were recovering over time,” Blamire said. “The areas of brain damage were not as widespread across the brain as previously, but focused in certain areas of the brain, which could indicate that the brain was compensating for the injuries.”
The study, supported by the Sir Jules Thorn Charitable Trust, was published in Neurology, the medical journal of the American Academy of Neurology.