It only takes mild trauma to the brain to cause brain damage that leads to cognitive and memory issues. This is the finding of a study funded by the Sir Jules Thorn Charitable Trust and published online in Neurology, the journal of the American Academy of Neurology in 2014.
The study compared 44 people with mild brain trauma and nine people with moderate brain trauma to 33 people who had not experienced any kind of brain trauma. Researchers tested participants’ cognitive skills and memory. Participants were also given diffusion tensor imaging scans. These scans are a kind of MRI that is better able than conventional MRIs to identify damaged brain cells. This type of MRI can also help to outline the pathways that connect different areas of the brain. Those who had brain injuries were given their scans an average of six days after the trauma. Brain injury is considered mild if unconsciousness, disorientation or confusion lasts less than 30 minutes. Injury is considered moderate when these effects last more than 30 minutes, but less than 24 hours.
When the results of the scans were compared with the scans of those who had not suffered brain injury, those with brain trauma showed damage in the white matter that appeared as damage to the axons. Axons are the part of nerve cells that are known as white matter in the brain. Axons are the way the brain cells relay messages from one to the next.
Patients with traumatic brain injury scored an average of 25% lower than individuals without brain injury on tests of verbal letter fluency, cognitive skills and memory. The differences in results correlated strongly with the amounts of damage to white matter as measured by the imaging scans.
A year after their first scans and tests, 23 of the brain injured participants had repeat scans and were again given similar tests of cognition and memory. The scores of the brain injured participants at a year after the trauma were similar to their uninjured counterparts, but their scans still showed evidence of the damage.
Study author Andrew Blamire, PhD, of Newcastle University in the United Kingdom explained that most studies that have been previously conducted on brain injured patients have concentrated on severe traumatic brain injury, and not more moderate and mild brain trauma. This study was the first to examine the effects of brain injuries that were clinically more mild and resulted from everyday incidents such as falls from a bicycle and low speed car crashes. He points out that 90% of all brain injuries are mild to moderate, making the results of this study especially important. “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.”