Medical researchers say they can predict which NFL players will suffer brain damage decades after they hang up their cleats by looking at their history of concussions – as well as their reading ability, job history and general life skills.
A new study by neurological researchers at the University of California, Los Angeles developed a formula that uses "cognitive reserve," a measure of a person's experiences and how they handle stressful situations such as a demanding job.
They combine cognitive reserve with a detailed look at how many concussions they suffered, how often they occurred and whether they suffered any kind of amnesia as a result.
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"We are trying to come up with rules of thumb for concussions, but I think we need a data-driven approach that can be used to forecast if you had another concussion, how would you look down the road," said Matthew Wright, a clinical and cognitive neuropsychologist at the Harbor-UCLA Medical Center and lead author on the paper published Monday in the Journal of Clinical and Experimental Neuropsychology. The study was conducted by Wright and colleagues at UCLA and Boston University.
"Some players will do better than others," Wright said. "The index can be used to predict whether somebody has normal cognition or may be severely impaired."
The study reviewed the cases of 40 former NFL players who had been retired for an average of 20 years. Many of the participants had suffered "cognitive deficits," according to the study.
Players who had a higher cognitive reserve did better than those that did not.
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"Having a higher cognitive reserve means there is a greater neural efficiency in the brain, so you can take more hits," Wright said.
Other studies have linked cognitive reserve with higher education and IQ, or the ability to make flexible and efficient use of available brain reserve during tasks. Having a high cognitive reserve can also help in warding off the effects of diseases of aging like Alzheimer's.
Of course, smart football players who get pounded more times during their college or pro careers will have more problems that less-intelligent ones who don't, said Wright.
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The most important variable is whether the player had post-concussion amnesia -- for example, whether he could remember what he did the day of the game.
"We found that a more powerful factor than the loss of consciousness," Wright said.
One neurologist who works with NFL players questioned the format of the study and whether the results are accurate.
"The biggest criticism is that it uses people later in life trying to remember what happened to themselves 30 or 40 years earlier," said Kevin Crutchfield, director of the Sports Neurology Center at LifeBridge Health in Maryland.
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Crutchfield, who is a consulting neurologist with the Baltimore Ravens, Baltimore Orioles and DC United soccer team, said a more accurate study would follow a larger group of players over time, rather than trying to reconstruct their past.
Wright said his index is just a start. However, when refined, the index could be used to help current players make decisions about when they have had too many hits.
"It's a proof of concept, not something we can go out and use right now," Wright said. "But it accounts for large amount of cognitive variance 20 years out."