During a football game last October, an opposing player head-butted Jordan Sawyer, a six-foot-two, 220-pound offensive lineman at Chicago’s Walter Payton College Prep High School. “There was one giant blow where my head just hurt,” he says. “[It] was really killing me.”

At the time, Sawyer, then 17, didn’t think much of it. After all, unlike his friends who had suffered a concussion, he did not feel dizzy or throw up. So he put some ice on his head and played the second half of the game.

That weekend, Sawyer’s mother, Marla Kushner, a volunteer team doctor at the school, made sure her son took a cognitive test—and the results showed that he had a concussion. The following Monday in school, the normally nimble linguist had trouble focusing on words. That same day, Sawyer saw a neurologist, and for a while, he took it easy. But three weeks later, during drills with his team, he received a second concussion. The doctor told him he needed to take six weeks off from football (which was winding down for the season anyway). “Otherwise,” Sawyer says, “I’d risk brain damage.”

Scared, he listened. “I realized I could really screw myself over,” acknowledges Sawyer, who heads to Michigan State this fall. “I haven’t played any contact sports since then.”

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Each year, more than 1.5 million people in the United States suffer a concussion with loss of consciousness. “Concussions are ubiquitous,” says Christopher Randolph, director of the neuropsychology service at Loyola University Medical Center.

But those blows are far from innocuous. They can cause headaches, confusion, and trouble with concentration, memory, balance, and coordination. (In Sawyer’s case, the mental aftereffects continued for weeks.) Preliminary evidence suggests that repeated concussions can lead to the onset of dementia-related symptoms—a major problem for athletes in high-impact sports such as football. A study coauthored by Randolph found that 61 percent of retired professional football players had had at least one concussion and that 24 percent had had three or more. With the February suicide of the former Bears safety Dave Duerson—who shot himself in the chest in order to preserve his brain for future study—concussions are getting even more attention.

“Concussions are indeed a mystery,” says Hunt Batjer, chairman of the department of neurological surgery at Northwestern Memorial Hospital and cochair of the National Football League’s medical committee for head, neck, and spine injuries. “There are a thousand things we don’t know.” Among them: “How can a condition that presents clinical symptoms that are unassociated with obvious structural changes ultimately lead to permanent neurological damage?”

But there is one thing about which Batjer is certain. “Does repetitive brain injury put you at risk for permanent neurological problems?” he asks. His answer: an unequivocal yes.

There lies the problem. Loyola’s Randolph notes that, beginning in high school, about 4 to 5 percent of football players will get a concussion each year—and repetitive blows to the head are even more commonplace in professional and college football. “The average college football player can sustain over 1,000 blows to the head in excess of 10 Gs every year,” he says, explaining that that’s the equivalent of a robust slap to the head. (Hits in the range of 100 to 150 Gs are not uncommon in the National Football League.) “I think the issue is the quantity of cumulative impact overall,” Randolph adds. “Your brain is meant to take a certain amount of punishment. But the more concussions you have, the more likely you are to have another one”—which is why he suggests that high-school and college football coaches reduce the number of full-contact drills in practice.

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Doctors aren’t the only ones concerned about the long-term effects of concussions. Earlier this year, the City of Chicago passed an ordinance requiring athletes to sit out the rest of a game when they exhibit symptoms of a concussion; they also need written medical clearance before they can play again.

At the state level, similar legislation has passed in both the House and Senate; at presstime, it awaited the approval of Governor Pat Quinn, who was expected to sign the bill. It is based on a state law in Washington named after Zackery Lystedt, a middle-school football player who suffered permanent brain injury when he returned to play after a concussion in a 2006 game—only to take a second hit that caused a brain hemorrhage. After years of therapy, the wheelchair-bound Lystedt has resumed some semblance of a normal life, which makes him one of the lucky ones. In some cases, the so-called second-impact syndrome can be fatal.

“[The new legislation] really takes all of the social stigma out of [declining to play after a concussion] and makes it a purely medical decision,” says Cherise Russo, a doctor who treats many young athletes at the Northwestern Orthopaedic Institute. “Sports like football and hockey—these kids want to be tough,” adds Kwame Raoul, an Illinois state senator—and the father of a 13-year-old football player—who was one of the sponsors of the Illinois legislation. “They don’t realize the potential impact of returning to play prematurely.”

Kids take seven to ten days longer than adults to recover from a concussion, says Holly Benjamin, a specialist in sports medicine and musculoskeletal injuries at the University of Chicago’s Comer Children’s Hospital. After suffering a blow to the head, they should be cautious about overdoing schoolwork, texting, and watching TV—and teens who are old enough to drive should refrain for a while (their reaction time will be slower). “You crawl in a cocoon if you want to get better faster,” she says. “They just have to be quiet and eat and sleep. No exercise. No caffeine.”

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Some local doctors are taking the message directly to student athletes. Daniel Derman, president of the Northwestern Memorial Physicians Group, is surveying the football teams at seven local high schools: New Trier, Evanston, Glenbard East, Prospect, Chicagoland Jewish, Waukegan, and Lake View. As part of a preliminary effort to reach out to all of the state’s 300,000 high-school athletes, he wants to teach students, coaches, and parents at the seven schools about concussions and their repercussions. Among other things, he hopes to ensure that athletes are wearing proper helmets—not just “repurposed” ones used by players in previous years.

Derman also wants to determine each player’s base-line cognitive score on a computerized neurocognitive test called ImPACT. Players could then retake the test within 24 hours of a hit to the head, and doctors would be able to measure any changes to their cognitive abilities.

The pending state legislation—which also requires the Illinois High School Association (IHSA) to provide educational materials to all elementary and secondary school districts—should help elevate awareness about concussions. “It’s going to make it easier for young kids to battle that peer pressure to return to play sooner than they need to,” says Marty Hickman, executive director of the IHSA. “They’re going to understand it’s not worth the risk.”

To further educate high-school coaches, trainers, and athletic directors—as well as the parents of student athletes—Northwestern Memorial Hospital, the Northwestern University Feinberg School of Medicine, and the IHSA are joining forces to present a symposium called “Playing It Safe: Changing the Mindset Around Concussion Safety in Sports.” The event—at Northwestern’s downtown Feinberg Pavilion on July 27 from 8 a.m. to 1 p.m.—is free, but preregistration is required. For more information, call 877-926-4664 or go to northwesternmedicine.org/playingitsafe.