Breaking Down the Study on Former NFL Players, Brain Injuries and Youth Football

Last week, a study was published in the medical journal Neurology about the cognitive performance of retired NFL players, based on how early they had started playing tackle football. The general findings were that the group of players that had started playing tackle football before age 12 performed worse on cognitive tests than the other NFL players tested.

This, of course, has potential ramifications going forward, beyond just looking at some retired NFL players. Dr. Robert Cantu has stated that kids should not play tackle football before age 14 because their brains are still developing.

"The reason is simple. Tackle football is too dangerous for youngsters. Exposure to head trauma is too risky. What we know about football and the vulnerabilities of children’s brains leads me to this conclusion. More worrisome is what we don’t know. How will the hits absorbed by a 9-year-old today be felt at 30, or 50?"

I talked with Julie Stamm, the person who spearheaded the recently published Boston University study. Stamm, a doctoral candidate in anatomy and neurobiology, is a certified athletic trainer who worked at both the major college and high school levels with football players. “It was the time seeing the kids in high school that really spurred me with this line of research,” she said.

So what was this study, and how did it come about?

It’s part of a larger DETECT study at Boston University, researching CTE in NFL players. There are currently 74 players in that study, though not all were selected for this sub-study into the impact of age of onset of playing youth football.

“When we looked at the two groups, just dividing them [into those that played tackle football] before 12 and after 12, there was a significant difference in age,” Stamm said. “The ones that were older didn’t have as many opportunities to play the sport before age 12, because at the time, those opportunities just weren’t around. So, we felt it was better to use these age-matched pairs, rather than just trying to correct for age. That’s how we got to 42 players, 21 for each group.”

The assignment of players was random, trying to get as many matched pairs as possible with one former player from the under 12 and one from the 12 or over group. Those players had undergone cognitive testing and the results across the two groups of pairs were compared.

One of the tests used was the Wisconsin Card Sorting Test (you can see a demonstration here). It’s testing the ability of the subject to properly sort a series of cards by rules (color, number, shape) based on rules, which can change after enough correct answers.

The former NFL players in the DETECT study who had started playing football at 12 or older averaged a score of 45 (50 is an average score for the population). Those who began playing tackle football before age 12 averaged a score of 37.

The study has its limitations, primary of which is the limited number of subjects so far. Because of the age/youth football experience issue, the number of participants were reduced even below the 74 former players in the larger study.

Also, as of right now, only former players who have complained of cognitive difficulties are part of the study, and going forward, testing on a larger group of retired NFL players would be necessary. “That’s a huge thing we need in future research, is people who aren’t complaining of symptoms,” Stamm said, “But I also think it’s striking that even within a group that is complaining, we still see quite a significant difference between those that started [playing tackle football] earlier.”

Stamm mentioned doing larger cross-sectional studies that could include former college players, or even those that played through high school, to increase the sample sizes. The ideal study, though, is what is termed a longitudinal study: following the same kids around from testing through early adulthood.

“For kids, for example, the executive functions in normal-developing people don’t develop until the late teens and early twenties,” Stamm said. “The thought is that with concussions, if someone has a concussion when they are eight years old, they may have a difficulty with executive functioning when they are twenty. It’s not always attributed back to that injury in childhood. They seem like they’ve compensated and figured out how to get through life without that skill. That’s something that needs further research, and something we can’t figure out unless we have longitudinal studies in the future.”

The big problem, in addition to cost? Time. That is a fifteen year study. Think about what we were talking about in the year 2000 in regard to head injuries and football, and how much we have changed and learned in the interim. A hypothetical study that would have begun before 2000 would just now be wrapping up and ready for peer review.

Do we have that long, until at least 2030, to wait for a massive study following a generation of children to assess contact sports? It’s one step, but probably not. Our view may be totally different by then, independent of a study.

Stamm concluded with what drives the motivation for studying this issue. “We really think kids should play sports. Sports are really, really important for kids for so many reasons, learning leadership skills, work ethic, social relationships, health benefits. We just want to figure out how they can play these sports safely.”

[Images by USA Today Sports, youth football image by Concussion Blog]