Ask Dr. Hallberg: Traumatic brain injuries

Football season is in full swing, and with it, we've seen more focus on concussions and traumatic brain injury.

The New England Journal of Medicine recently published an article linking repeated head injuries to more serious brain disease. The military is also reviewing NFL guidelines about the value of full recovery intervals between concussions.

MPR News medical analyst Dr. Jon Hallberg joined All Things Considered host Tom Crann on Thursday to discuss concussions and traumatic brain injury.

Hallberg is a physician in family medicine at the University of Minnesota and medical director of the Mill City Clinic in Minneapolis.

Tom Crann: How is (a traumatic brain injury) different from a concussion?

Dr. Jon Hallberg: About 20 years ago, when I was in medical school, the accepted definition of concussion was a transient or temporary loss of consciousness. If someone got knocked out playing sports, they had a concussion, it was pretty clear. But what's really obvious now is that you don't need to be knocked out to have a concussion.

Crann: This past baseball season the Minnesota Twin Justin Morneau was out for much of the end of the season because of an earlier concussion. It's football season and there's a lot of attention being paid here in both the NFL and at the school level. How much attention?

Hallberg: There's so much more attention. The NFL's now mandating that posters be in all of the NFL locker rooms, indicating that repeated head injury can be serious. The fact that Justin (Morneau) sat out half the season basically attests to that as well.

I've even experienced it a little bit with my son, who is 30 years younger than I am, (and) is now playing football. (In the) late summer, we were told, as parents, the kinds of helmets they're going to wear, the fact that they have to be approved and have a certain degree of protection in them.

These kids also had to take computerized tests to sort of assess their cognitive function when they're at their best. In case they get their bell rung or get some traumatic brain injury, they can sort of be tested, and then they can use that as a baseline to know when they're ready to go back and play.

Crann: What actually happens inside your head during one of those bell-ringing episodes?

Hallberg: You've got the skull that's protecting the brain. You've got very rigid, hard tissue protecting very soft fragile tissue. When you are moving and you suddenly stop, the skull has stopped, but the brain has not. And there's a little bit of extra movement that's involved. So it's sort of squishing up against the side. That's sort of an obvious (way of looking at it).

We can all imagine that happening, but it's also more than that. We think that there might be -- on a very, very microscopic sub-microscopic level -- swelling that's going on. That the axons, which is the middle part of a nerve cell, gets stretched, and so the messages have a hard time. They're not connecting to one another, the nerve cells, the way they should.

Crann: What is the most serious lingering effect we're dealing with here?

Hallberg: What they've found is that if people have serious traumatic brain injury -- that they've been sort of knocked unconscious for 30 minutes, let's say -- they have a much greater chance of actually developing Alzheimer's disease. In fact, if you look at people with Alzheimer's, a higher percentage of them have had traumatic brain injury than those who have not developed that.

We think it's because there's these proteins that sort of degenerate the nerves, these amyloid-beta proteins. They're the exact same proteins involved in Alzheimer's disease.

Crann: And also this idea of the cumulative effect makes it worse down the line?

Hallberg: Yes, and some of that's coming from the boxing studies that have been done. We've all heard about punch-drunk syndrome, and what they've found is that it didn't matter what your win-loss record was for retired boxers, but it was how many rounds did they go in the ring. The more rounds and the more head pounding that they took, the greater the chance that they developed Parkinson's or an Alzheimer's-like picture.

Crann: What do you tell your patients and their kids, or even what advice do you have for your own son who's playing football, about this?

Hallberg: We're all agreeing that it's not cool to fight through this and push through it. If you've had your bell rung, if you feel funny, you're not remembering things very clearly, that you're not hearing things quite right, you've got to step out of that. You've got to tell somebody. Then we need to really take our time until that athlete has recovered from this sort of injury before going back in.

(Interview edited and transcribed by MPR reporter Madeleine Baran)