Last week, when former NFL linebacker Junior Seau died from a self-inflicted gunshot wound to the chest, the familiar debates resumed. Was this another Derek Boogaard? A tragedy that can best be understood by looking at the individual's history of blunt-force trauma to the head?
The long-term consequences of head injury are being debated everywhere, in anxious discussions about whether football should be banned, whether hockey should be sanitized, whether high-school sports are causing teens irreparable harm, and whether soldiers should be sent on consecutive tours in a war fought with IEDs.
Head injury, says Jamshid Ghajar, president of the Brain Trauma Foundation in New York, “is like the Ebola virus. We don’t know where it’s going to come from, we don’t know who it’s going to hit. And it could happen anywhere, at anytime.”
As society gains an increasingly sophisticated awareness of the human brain, we're seeing a heightened demand for more accurate methods of identifying and responding to head injury. Many of us, then, might be surprised to learn just how much ambiguity remains in understanding that so-called mild brain injury we hear so much about: concussion.
Even the most basic question is yet to be answered: what is it? There’s no standard definition of concussion. Quite the contrary—there are more than 30, each with varying criteria, each one subject to a doctor’s discretion. There are a host of symptoms that can lead to concussion diagnosis, like dizziness, headaches, loss of consciousness, problems with balance, and memory lapses. But many of these symptoms depend on what the patient says he or she is experiencing, which means that diagnosing concussions is often at least partially a subjective process.
The Brain Trauma Foundation, which gained renown a decade ago for vastly improving treatments for coma, has now become a major player in trying to solve the puzzle of concussion. “Most of the public thinks we already know what concussion is,” says Ghajar. “But no, we still have to go back and define it. Once we define it, then we can move forward and find out what’s causing all these problems.”
To this end, the foundation, together with the Centers for Disease Control and Prevention, are working to establish one standard definition. Their research is funded by the Department of Defense, one among many institutions with a vested interest in understanding the exact nature of mild brain injury.
It’s long been evident, however, says Ghajar, that “the major brain function change that occurs in a concussion after head injury is attention. People can’t pay attention as well.”
“Most of the public thinks we already know what concussion is. But no, we still have to go back and define it."
This impaired ability to pay attention is tied up with all the cognitive problems that can follow from concussion: difficulty concentrating, impaired reaction times, lapses in memory. Impaired attention is, in fact, one of the main reasons why getting one concussion raises your chances for subsequent concussions. If you can’t properly attend to the world flying at you, you are significantly more likely to smack right into it.
“You have to understand the workings of attention to understand what a concussion is,” Ghajar says. “So we had to step back and really think about it. And we realized that attention is the front end of processing. You focus in on what you want to pay attention to and then you process it.”
We’re often not even aware of it, but focusing on the world around us requires an ability to predict exactly when things will occur: when to put out our hand to give a handshake to the person walking toward us, when to start swinging in order to hit the baseball hurtling our way. Doctors have observed that after concussion, people can temporarily lose the ability to perform this kind of automatic predictive timing that most of us take for granted.
The Brain Trauma Foundation has even invented new technology—a pair of high-tech goggles—that can measure predictive timing by tracking eye movement, the way someone moves his or her eyes to follow a moving image. In 30 seconds, the software in the goggles can produce a measure of how well that person is able to sync up with the target he or she is looking at. The U.S. military is testing the goggles now for use as a measure of cognitive performance, hoping to be able to determine soldier readiness on the spot.
But eye tracking will likely prove to be only one element of characterizing concussion.
“Everyone’s looking for a diagnostic for concussion," says Ghajar. "But at the end of the day, there’s never one thing that makes a diagnosis."