Exposure to Tackle Football at Young Age Linked to Later Cognitive Problems
Former National Football League players who began playing tackle football before the age of 12 fared worse as adults in terms of executive function, memory, and estimated verbal IQ compared to those who began playing tackle football later, according to a study published online Wednesday in the journal Neurology.
The authors examined 42 former National Football League players between the ages of 40-69, dividing them into two groups: those who played tackle football before the age of 12 and those who began at 12 or later. Each player underwent three specific neuropsychological tests: The Wisconsin Card Sort Test, which measures executive function; the Neuropsychological Assessment Battery List Learning test, which measures verbal memory; and the Wide Range Achievement Test, 4th edition, which is a word pronunciation test that measures verbal IQ. The study authors sought to determine whether the age of first exposure to football had an impact on later-life cognition, hypothesizing that those who began earlier would perform significantly worse.
Among these 42 players, the authors' hypothesis proved correct. The 21 players exposed to tackle football before the age of 12 fared significantly worse on all three tests than those exposed at 12 or later, even after controlling for education and duration of play.
"They were worse on all the tests we looked at," said lead author Dr. Robert Stern to ESPN.com's Tom Farrey. "They had problems learning and remembering lists of words. They had problems with being flexible in their decisionmaking and problem-solving."
Notably, those exposed to football at an early age averaged two fewer years in their NFL careers than those exposed later. "Longer duration of NFL play could have been expected to contribute to poor cognitive performance in the [latter] group," Stern and his colleagues wrote, but the opposite proved true. However, the latter group did fare worse than average in many of the tested measures, so it's not as though the study is suggesting exposure to tackle football after the age of 12 comes without the chance of long-term consequences.
Based on the study's results, the authors conclude that "sustaining [repeated head impacts] during critical periods of brain maturation could alter neurodevelopmental trajectories, leading to later-life cognitive impairments." They highlight the ages of 10 to 12 as a particular concern, since it is a "period of peak myelination rates and increased cerebral blood flow, which has been shown to predict rapid neurodevelopmental periods" .
Stern and his colleagues note that the small and specific sample size—namely, only former NFL players within a 30-year age range—is a limitation of the study, as it's unclear whether the same would hold true with youth-athletes in other sports, or with female athletes. Dr. Julian Bailes, the chairman of Pop Warner's medical advisory committee, dubbed the study "flawed," in speaking with Farrey.
"There's absolutely no information on the number of concussions that the [study subjects] had in high school or college, or the severity of the concussions," Bailes said. "I think what probably happened is lots of them get no concussions in youth, but three in high school, five in college and 10 in the NFL. They're trying to say it's the age of first exposure that is the problem, when it's more likely cumulative exposure."
This study isn't the first time doctors have banged the drum for limiting youths' exposure to tackle football. In his 2012 book "Concussions and our Kids," Dr. Robert Cantu, the co-director of Boston University's Center for the Study of Traumatic Encephalopathy, recommended restricting youth-athletes under the age of 14 from playing tackle football.
In speaking with Cantu about why he chose age 14 specifically, he explained his rationale behind the recommendation:
It's a good question. Some people at age 14 are physiologically 11 or 10. Other people are skeletally mature adults. So, the age is not perfect, no age would be. I chose it simply because that means high school and above. You have to start playing sports at some point similarly to the way you're going to play them in college, if you plan to play them at college. I use the age of 14—and don't have any problems with 16 or 17 if [the student-athletes aren't] skeletally mature—but the reason besides that is the increased vulnerability of youngsters. ... They're bobble-head dolls with big heads and weak necks.
I also asked him whether he's lukewarm about youths' participation in contact sports such as football and ice hockey after the age of 14. He replied:
I am if they're skeletally immature. If they haven't developed any pubic or axillary [armpit] hair, I think you can make the case that you should hold them out a bit longer. I feel very strongly that if an individual starts playing a sport in high school, they'll be up-to-speed with someone who's been playing the sport since age 5 by college. It'll make you better at those early years, but it won't make you better by the time you get to college. Tom Brady is a good example. His dad held him out of tackle football until high school, and he doesn't seem to be any worse for the wear, does he?
In a world where 8- and 9-year-old football players are the stars of a reality TV show, the results of this study—and Cantu's recommendation about limiting exposure to tackle football at a young age—are certainly food for thought.
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