Questions linger about long-term impact of hits to the head

During a recent debate addressing whether the United States should ban college football, an argument against the sport was summed up this way: Schools should not be in the business of encouraging young men to hit themselves over the head.

The reasoning behind that argument (by New Yorker magazine staff writer Malcolm Gladwell ): Concussions  are not what afflicts football, rather it is the cumulative effects of punishing, comparatively subtle, subconcussive hits.

"There isn't a helmet in the world that can be designed to take the sting out of those hits," said Gladwell, at the Intelligence Squared Debate  hosted by Slate Magazine in New York last week. "What's the effect of all that neurological trauma? We know it's a condition called CTE."

CTE , or chronic traumatic encephalopathy, is a degenerative brain disease found among contact sport athletes - and associated with repeated head trauma - that can lead to dramatic cognitive, memory and mood problems. What scares some people about CTE is that it resembles dementia , except that it can strike people in their prime.

And considering a football player could suffer around 8,000 subconcussive hits to the head across four years of high school and college games, those hits would seem to be a recipe for neurological disaster for millions of athletes.

Yet so far, studies have not proven CTE to be a compelling issue for more than a fraction of them.

"The question that's being framed is, 'Is hitting your head bad for you? Is it going to lead to all sorts of terrible troubles down the road?'" said Dr. Thomas McAllister, director of neuropsychiatry at the Dartmouth-Hitchcock Medical Center . "That may be wrong question. The better question may be, 'For whom is that exposure bad?'"

In a study of college football players at three Division I universities, McAllister and his colleagues found that subconcussive hits were not causing the dramatic lapses in cognition that might be considered a precursor to CTE. But when they re-examined the data, they found something slightly alarming.

A significant subgroup of the contact sport athletes - 22% - performed worse than expected on tests of verbal learning, compared with only about 4% of the non-contact sport athletes.

The data were gathered by nestling sensors in the helmets  of 214 varsity football and hockey players and recording subconcussive hits during one full season. The sensors measured things like the force, location and rotation caused by hits to the head.

The contact sport athletes were compared to a control group of 45 athletes participating in non-contact sports like track, crew and Nordic skiing. Each group took cognitive tests before and shortly after the season.

According to the study, published in the journal  Neurology , by the end of the season some contact sport players came up short on those tests.

"It's a good news-bad news thing," said McAllister. "The study suggests that at a group level, a single season of contact sports is not associated with widespread systemic changes in cognition for the majority of people."

"But it has to be qualified that for some, that may not be true," he added.

Other data, including a similar study from researchers at University of North Carolina at Chapel Hill , suggest that subconcussive hits do not cause short-term neurological problems after one season. But there is no verdict - yet - about whether they are causing long-term problems, such as those associated with CTE.

"[The McAllister study] does keep the door cracked for the possibility of season-long effects from head impacts in certain athletes," said Kevin Guskiewicz , co-author of the UNC study and chair of the department of exercise and sport science at UNC Chapel Hill, in an e-mail.

"Let's say there is a subgroup," said McAllister. "What is it about those people that makes them more vulnerable to impact and how can we identify who they are in advance?"

These are questions that cannot be answered by the current crop of scientific studies.

And what about the risk of CTE among college football players?

"It has not been proven, in my view, that everyone who has these repetitive hits to the brain gets CTE," said McAllister. "Sadly, there is a lot that we still don't know."

As for the debate to ban college football - Gladwell's team, arguing in favor of banning the sport, won.