An athlete's brain may still not be fully recovered one year after being allowed to return to play, according to new research.
In a study published in the latest online issue of Neurology, the medical journal of the American Academy of Neurology, researchers used magnetic resonance imaging (MRI) to scan the brains of 24 college athletes with concussion and 122 without concussion.
For athletes with concussion, the first scan was performed an average of four days after injury. There was then a second scan when the athlete was cleared to return to play and a third scan one year after return to play. Athletes who did not have concussion had one brain scan at the start of their seasons. Brain scans of the concussed athletes were compared with the brain scans of the healthy athletes.
"There is growing evidence that recovery from a concussion may not be complete even when symptoms such as headache and dizziness are gone and the athlete is allowed to return to play, so it is important to determine if various aspects of the brain injury resolve over time or are perhaps permanent," explained study author Nathan W. Churchill, PhD, of St. Michael's Hospital in Toronto, Canada.
The analysis revealed that the brain scans of concussed athletes still showed signs of brain injury when they were allowed to return to play, and there was also evidence of brain injury a full year after return to play.
When compared with healthy athletes, those who returned to play after concussion had significantly reduced blood flow in the brain one year later. When examining brain scans that map how water molecules move in the white matter of the brain, the researchers also found the brains of concussed athletes still showed possible signs of tissue swelling one year after return to play.
However, measurements of brain connectivity had returned to normal one year after return to play. This included measurements of both the patterns of resting brain activity in the brain's grey matter and measurements of the lines of communication in the brain's white matter.
The long-term effects of concussion in the brain depended on the severity of an athlete's symptoms and how long it took them to return to play.
"The principal finding of this study was that different aspects of brain physiology have different patterns of long-term recovery," Dr Churchill added. "These findings significantly enhance our understanding of the natural course of brain recovery after a concussion. Future studies are needed to look beyond one year after return to play to see if these longer-term brain injuries eventually heal or remain permanent."