Concussions in college athletes lead to brain changes lasting a year

For college athletes with concussion, brain changes may remain visible in brain scans up to a year after they are cleared to return to play, according to a study published on March 12, 2025, online in Neurology^®, the medical journal of the American Academy of Neurology (AAN).

Concussion can have long-term effects on brain health, and there is growing evidence that brain recovery may persist months to years, even after symptoms like headache, fatigue and balance problems resolve. Our study followed athletes before and after concussion for over a year, using multiple brain scans to examine biomarkers that signify brain injury. Our results provide strong evidence, suggesting incomplete recovery of brain function when returning to play and beyond."

Nathan Churchill, PhD, author, St. Michael's Hospital in Toronto, Canada

For the study, researchers looked at 187 college athletes, of which 25 had concussion during regular season play. They competed in the following sports: basketball, football, hockey, lacrosse, rugby, soccer and volleyball. The concussed athletes were also compared to 27 athletes without concussion, matched for factors such as sex and sport.

Athletes completed pre-season testing for factors such as balance, thinking and memory. They also had a magnetic resonance imaging (MRI) brain scan before their seasons began.

Participants who later had concussions had additional brain scans at the following stages: an average of five days after concussion; when cleared to return to play; one to three months after returning to play; and one year after returning to play. Those without concussion had brain scans during their next pre-season assessment. Brain scans of the concussed athletes were then compared to their own pre-injury brain scans, and these brain changes were further compared to those of healthy athletes.

Researchers found that the brain scans of concussed athletes still showed signs of brain injury when they were allowed to return to play and up to one year later.

When compared to their pre-injury brain scans, those who returned to play after concussion had significantly reduced blood flow in the brain in the fronto-insular cortex, a part of the brain that helps control thinking and memory, emotion and social behavior. Specifically, at return to play, concussed athletes had an average decrease in blood flow of nine milliliters (mL) per 100 grams of blood per minute compared to healthy athletes. At one year, they had an average decrease of 11 mL per 100 grams of blood per minute. These blood flow changes were also greater than those seen in uninjured athletes.

When examining how water molecules move in the white matter of the brain, researchers also found the brains of concussed athletes still showed possible signs of brain injury, compared to their pre-injury brain scans.

"The presence of significant, long-lasting brain changes after injury reinforces concerns about the consequences of repeated concussions, and to what extent these effects accumulate over time," said Churchill. "More studies are needed in larger groups of people to further investigate the long-term effects to the brain."

A limitation of the study was that it included only young athletes with concussion. Churchill noted that future research should also follow non-athletes with concussion as well as people in other age groups.

The study was supported by the Canadian Institutes of Health Research, the Canadian Institute for Military and Veterans Health Research and Siemens Healthineers Canada.