The brain on the table once belonged to a pro football player. It’s also much bigger than average, so it may have been the brain of a very big man—perhaps he played lineman. Those are the only things I know about it before Ann McKee starts cutting it into pieces.
Several minutes later something else is becoming clear: this brain is pretty messed up.
“I think this guy had CTE,” says McKee, a professor of neurology and pathology at the Boston University School of Medicine and director of neuropathology for the New England Veterans Administration Medical Centers. She and her colleagues will ultimately examine the brain’s tissue down to the microscopic level to determine for sure whether it was afflicted with the progressive neurodegenerative disorder called chronic traumatic encephalopathy, or CTE. But she can already see telltale patterns of atrophy, or shrinkage of the delicate tissue in several areas.
I’m part of a small audience watching as McKee proceeds to slice this football player’s brain up like she might a loaf of bread. As she goes along, she lays the slices on the table and points out various signs of disease.
“It’s amazing what they do to their brains,” she says more than once with a hint of exasperation. We’re in a lab on the campus of a VA hospital just outside of Boston, where McKee runs the nation’s leading brain bank studying the effects of head trauma. In recent years this has become a popular destination for the brains of pro football players, usually donated shortly after death by family members who want to help the researchers develop a better understanding of CTE.
Many studies over the past decade and a half, including prominent work from McKee’s group, have linked the disease—whose outward signs include cognitive difficulties, mood disorders, headaches, suicidal thoughts, and aggressive behavior—to the type of repetitive head trauma experienced by many football players and other athletes who play contact sports (see “Are Young Athletes Risking Brain Damage?”).
The brain I’m watching McKee calmly disassemble seems to be telling an undeniable story about what football did to it. Indeed, the whole body of evidence her group has collected seems to tell an undeniable story. McKee and her colleagues have found evidence of the disease in 88 of the 92 brains of former NFL players they’ve studied, and in 45 of 55 brains of former college players. But as striking as they are, these numbers should be taken with a grain of salt. As McKee acknowledges, it is a biased sample, since in many cases the family donated the brain because they already suspected a problem.
The numbers don’t tell us how common the disease is, and they don’t even tell us much about the role of concussions. When she first started studying CTE, McKee says she thought concussions were “the key.” Now she and her colleagues are finding that about 20 percent of the individuals diagnosed with CTE suffered head trauma but never had a documented concussion. There are also cases in which the patient had a relatively large number of recorded concussions and didn’t develop the disease.
In other words, the brains of deceased football players can only tell us so much about how and why CTE arises. And the questions they leave unanswered have sparked a debate in the scientific community over the relationship between exposure to head trauma, symptoms, and the postmortem pathological findings. It’s not even clear if the disorder, which can only be diagnosed postmortem, is present in the general population of those who’ve experienced head trauma, says Rebekah Mannix, an emergency medicine physician at Boston Children’s Hospital and the co-director of the brain injury center there, as well as an assistant professor of pediatrics at Harvard Medical School. “It’s hard to make any kind of diagnostic criteria based on a self-referred population,” says Mannix.
McKee says her data suggests that the duration of exposure to repetitive head trauma—concussion-inducing blows as well as smaller, “subconcussive” hits—is correlating with the severity of the disease. Imperative, she says, are studies that use accelerometers to track the head impacts that individuals sustain, cumulatively, throughout their lives. Ideally, such studies would also track things like nutrition, neuropsychological performance, and other measures of health, she says, and scientists could eventually use that data to tease out important relationships.
Unfortunately that means it may take decades to clear up the debate over CTE, how and why it arises in individuals, and what that means for football players. But my experience at McKee’s lab convinced me that at least one thing is undebatable: it’s amazing what they do to their brains.