While fans flocked to the Superbowl tournament in the US Sunday, scientists were also trying to study the brain damages caused by head injuries.
Super Bowl decides the National Football League (NFL) champion and is a widely watched event. But scientists have another reason to make it there, to figure out how many NFL players are likely to experience debilitating brain damage later in life.
Head injuries and concussions in sports players can lead to severe brain degeneration long after the physical impacts have stopped, it is known. In the NFL, seven former players died of various causes before they were 50. Researchers are still trying to figure out how many players might be affected by brain problems and to what degree of severity.
Studies — mostly of boxers — show that at least 20 percent of people who suffer repeated brain trauma go on to develop degenerative brain disease, Dr. Ann McKee of Boston University's Center for the Study of Traumatic Encephalopathy told the NPR Radio.
McKee has examined the brains of seven former NFL players who died of various causes before they reached 50. The most recent was Tom McHale of the Tampa Bay Buccaneers, who died of a drug overdose last year at age 45.
McKee says these players' brains have the same sort of damage found in some aging boxers — the brain cells shrivel, and tangles begin to appear.
"You don't see anything like this in the normal population," McKee says.
The damage may not begin appearing until decades after a player has retired. But, she says, "once it's triggered, it just keeps on progressing."
And it can lead to memory problems, depression, incoherent thoughts and, eventually, dementia.
However, McKee says it's hard to use research on boxers to draw conclusions about football players. After all, football players wear helmets and aren't allowed to deliver blows to the head with their fists.
"There's so little we know about this," McKee says. "We need to find out how many hits. Do the hits need to come in close succession? Does it matter how old a person is when they get their injuries?"
She says it's also likely that some players carry genes that make them more vulnerable to head injuries.
McKee hopes to know a lot more after studying at least 100 brains from former football players. That will take years, though, because the studies can only be done on players who have died after agreeing to give their brains to science.
Even with more data it won't be easy to assess the risk to an individual player, says Mark Lovell, who runs the Sports Medicine Concussion Program at the University of Pittsburgh and consults for the NFL.
"You can see athletes who've had numerous concussions who seem to be functioning perfectly well," Lovell says. "You can see athletes who've had one concussion who aren't functioning."
Lovell says it's not even clear how many players actually sustain concussions during the season. That's because many won't say anything that might get them removed from a game. And medical technology doesn't offer trainers and coaches much help in getting a quick answer.
"The problem is that the traditional ways of detecting brain injuries, such as CAT scans, and MRIs and things like that are really not at all sensitive to concussion," he says.
Lovell says that may change in the next decade. In the meantime, he says, teams appear to be keeping players off the field longer than they used to after a blow to the head.