(CNN) - Over the past few years, physicians have been learning more about the long term effects of playing sports, especially when it comes to concussions.
"What it does to the brain, it can cause cells or tissues to strain or stretch that can result in cell dysfunction," said Ryan Tierney with Temple University.
Tierney has been investigating whether some athletes are more prone to developing concussions than others.
He tested more than 200 college football and soccer players to see if they had a specific variation of a certain gene that helps make proteins that repair neurons in the brain when they are damaged.
Out of 200, nine of those athletes had suffered multiple concussions, and eight of those had the same variation of the gene.
"Now this variation is normal throughout the population, but for people who are going to put themselves in an environment where they are going to receive repetitive head impacts, it becomes more important," Tierney said.
Although more research is needed, Tierney believes if concussions are genetic, scientists could ultimately come up with a saliva test that could alert athletes if they are prone to concussions.
It would also help coaches and athletic trainers make better decisions on how to treat certain athletes on the field.
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