A longitudinal study of college football players found alterations in the white matter in their brains after a single season. But the research also suggests that athletes might benefit from periods of rest where they abstain from head impacts.

“We had performed multiple imaging studies on contact sports athletes in the past where we found changes in white matter diffusion over the course of a single season of sport (and exposure to repetitive head impacts),” explained study author Inga Katharina Koerte of the University of Munich and Harvard Medical School.

“We were wondering whether those brain alterations are transient or persistent. This is why we decided to study a cohort of American Football athletes over the course of a play season and after a period of non-contact rest (athletic training but no hits to the head).”

The researchers examined the white matter of 15 male athletes from the University of Rochester football team before the start of the football season, after the season, and after six months of rest. They also examined five non-athlete controls.

The researchers used diffusor tensor imaging (DTI), an advanced type of magnetic resonance imaging that measurements of water movement along white matter tracts in the brain.

During the football season, the athletes were also monitored for concussions at every game. But none of the athletes sustained a concussion.

The researchers observed alterations in the brainstem, left temporal lobe, and left parietal lobe among the athletes after the football season. But, in some of the athletes, these alterations returned to normal after six months of rest.

“All players showed signs of brain alterations over the course of a play season of collegiate American football,” Koerte told PsyPost. “After a period of non-contact rest those changes resolved in most cases and persisted in some. This suggests that some individuals might be more vulnerable to repetitive head impacts and might either take longer to recover or won’t recover at all.”

The findings were recently published in the scientific journal Brain Imaging and Behavior.

The preliminary research had a small sample size, but provides opportunities for more research.

“Interestingly, in our sample, those with persistent white matter changes were among those with the hardest hits. Future studies need to investigate the association with frequency and force of sustained head hits and duration of recovery,” Koerte added.

“Also, we only included American Football players and head hits might vary between different contact sports. Future studies also need to identify other potential risk factors for persistent symptoms (e.g., sex) and should therefore include athletes of different contact sports and females. We also still don’t know the relationship with behavior and cognitive function with a more long-term perspective (e.g. later-life risk for anxiety and depression).”

The study, “White matter alterations in college football players: a longitudinal diffusion tensor imaging study“, was authored by Michael Christian Mayinger, Kian Merchant-Borna, Jakob Hufschmidt, Marc Muehlmann, Isabelle Ruth Weir, Boris-Stephan Rauchmann, Martha Elizabeth Shenton, Inga Katharina Koerte and Jeffrey John Bazarian.