As much as fans will have to spend to attend the Feb. 11 Super Bowl, the game of football costs some professional players a vastly higher price, particularly when it comes to brain health. Researchers have found high rates of chronic traumatic encephalopathy (CTE)—a degenerative brain disease characterized by memory loss, confusion, mood swings, violence, suicidality and more—in autopsy studies of professional football players. CTE is caused by the head trauma and whole-body hits that are characteristic of the sport, which can lead to the dangerous buildup of certain proteins around blood vessels in the brain.
Now it appears that the risk of brain trauma may also affect much younger athletes. According to a new study in JAMA Network Open, high-school football players can show alterations in brain tissue too. While it’s impossible to determine the presence of CTE without conducting an autopsy of the brain, the work provided disturbing evidence that playing the game early in life may lead to serious problems later on.
“It’s a risk,” says Keisuke Kawata, an associate professor of clinical neuroscience at the Indiana University School of Public Health, and a coauthor of the new paper. “There are some brain changes that are normal over time. But among adolescent football players, we saw changes that it usually takes until middle age to exhibit.”
To conduct their work, Kawata and his colleagues recruited 275 athletes from five Midwest high schools, 200 of whom were football players and 75 of whom participated in noncontact sports—specifically swimming, cross country, and tennis. All of the volunteers were males ages 13 to 18. Magnetic resonance imaging (MRI) scans were taken of their brains from May 2021 to July 2022, spanning two sports seasons.
The researchers discovered disturbing changes across multiple regions of the brain. One of the most significant was in the so-called sulcal regions, or the bottoms of the multiple folds that give the brain its characteristic cauliflower-like look. In a number of areas—including the cingulate cortex, which helps govern decision-making; the precentral gyrus, which controls volitional muscle movements; and the frontotemporal regions, which are broadly associated with personality, behavior, and language—the investigators saw a pronounced increase in sulcal depth. It is in the sulcal pits that spinal fluid can pool, and, when set in violent motion, can damage adjacent tissue.
“It’s called the water-hammer effect,” says Kawata. “The torque and force are more pronounced there, and we start to see possible degeneration.”
Pits were deeper in the football players than they were in kids who play noncontact sports, but the peaks of tissue around the sucal region, known as the gyri, were higher—again in the cingulate cortex, as well as in the frontoparietal region, associated with goal- or task-directed behavior; the precuneus, which, among other things, is involved in memory and mental imagery; and the lingual gyrus, which has a hand in memory and processing vision. The mechanism behind the growth of the gyri is not as clear as it is with the water-hammer effect, but there are clues. The researchers cite a 2016 study, which looked at mild cases of traumatic injury and suggested that elevated gyri might be a compensatory mechanism the brain switches on to support other impaired regions.
Elsewhere in the football players’ brains, the MRIs detected atrophy of tissue. The outer surface of the brain, covering both cerebral hemispheres and representing about half of the organ’s overall mass, is the cerebral cortex, which takes part in a range of functions including learning, reasoning, memory, decision-making, intelligence, personality, and emotion. The researchers found thinning across much of the cortex—a discovery that particularly worries Kawata.
Ordinarily, he says, “it takes years and years to show this kind of macro level structural change. Some studies show 30 or 40 years before we see such cortical shrink.”
The paper reaches no conclusions on what impact the cortical thinning has on the players’ cognitive processes; the cerebral cortex has so many jobs, distributed across so much brain area, that it will take further research to survey that landscape. But cognition and information processing are not the only functions in play. As with CTE and dementia, any changes to the morphology of the brain can have a hand in the development of psychiatric disorders. The researchers point to a 2019 paper which showed that increased cortical thickness and the growth of gyri in the cingulate cortex appear to be associated with major depressive disorder.
“This is quite relevant,” says Kawata. “[Professional] football players with degenerative brain disorders almost always have psychiatric comorbidities. They become combative, irritable, violent. The student athletes are very well-behaved, respectful, nice football players. But there is a neurological sign that they may be at risk for psychiatric conditions.”
For now, the investigators are not calling for a ban on full-contact football for youth, and Kawata, for one, sees virtues to the game. “It would be very detrimental to some kids to just go home in the middle of the season,” he says. “They’d be on the couch, eating chips and watching TV all day long. I think that's much worse than being on the field and learning.” But as the pros and scientists know, time on the field may exact a steep toll.
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