Research has shown that repetitive hits to the head are bad for an athlete's brain.
Now scientists are looking at how white matter, the part of the brain affecting how we learn and function, changes after multiple hits.
Researchers, led by the University of Rochester, studied 15 college students.
Ten were division-three college football players and the other five were non-athletes.
Compared to the non-athletes, the football players’ brains showed changes in white matter, and some of the players' brains had not recovered after six months of rest.
"We really found out that there are some hits that have no consequence, they are very low level, and then there are hits that accumulate over time to the point of equalizing, in a way, a concussion," said Damir Janigro, Ph.D. Cleveland Clinic
Researchers say the study shows there may be new ways to detect early signs of brain damage--using the white matter.