Jan 29, 2015
The Invisible Injury

While some aspects of concussion remain shrouded in mystery, medical research is offering a clearer picture than ever of how the brain reacts after injury. Armed with the latest information, you can make your concussion prevention and management strategies more effective.

By Kyle Garratt

Kyle Garratt is an Assistant Editor at Training & Conditioning. He can be reached at: [email protected].

In Chris Nowinski’s years as a defensive tackle at Harvard University, and after graduation as a World Wrestling Entertainment (WWE) performer, concussions weren’t something he worried about. He dished out and took his share of hits on the field and in the ring, but he never thought the blows had caused any significant trauma. However, his perspective changed abruptly during a WWE match in June 2003.

“I got kicked in the chin, and forgot where I was, what I was doing, and who was supposed to win the match,” recalls Nowinski. “Afterward, I had headaches, lethargy, nausea, and memory loss. When those symptoms didn’t go away, I started going to doctors. The eighth doctor I saw finally helped me understand what a concussion really is–and as we discussed my history, we realized I’d had six in the previous five years.”

As he learned more about concussions, Nowinski focused his energy on researching head injuries and raising awareness in the athletic world. In June 2007, he co-founded the Sports Legacy Institute (SLI), which is dedicated to research and education on concussions and concussion-related degenerative brain conditions. Today, the institute focuses on Chronic Traumatic Encephalopathy (CTE), a brain disease believed to be caused by repeated concussions.

Thanks to groups like the SLI and individuals like Nowinski, concussion research and education are constantly progressing, and more people are recognizing the need for extra caution when treating athletes who receive blows to the head. Recent studies have expanded our knowledge of the short- and long-term risks of concussions, return-to-play considerations, and ways to prevent and manage concussions to keep athletes as safe as possible.

“Concussions are a lot more serious than people once thought,” says Nowinski. “But if you treat them with the respect they deserve, you can prevent a lot of potential harm.”


In September 2008, the SLI partnered with the Boston University School of Medicine to form the Center for the Study of Traumatic Encephalopathy (CSTE). Their goal was to study and eventually prevent CTE, and the center has already succeeded in raising awareness of this serious condition. For instance, the CSTE grabbed headlines when it performed autopsies on six former NFL players between the ages of 36 and 50 who had suffered concussions during their careers, and found signs of CTE in all six. The researchers also discovered early signs of CTE in a recently deceased 18-year-old who suffered multiple concussions while playing high school football.

“This condition is unusual because it is progressive and appears to be triggered by repetitive trauma that typically occurs in a person’s earlier years,” says Ann McKee, MD, Associate Professor of Neurology and Pathology at the BU School of Medicine and co-director of the CSTE. “When athletes with CTE retire from their sport they usually appear to be fine. The symptoms get worse and worse as they age, and it becomes really noticeable by their 40s and 50s.

“That’s when we typically see behavioral changes,” continues McKee. “Sometimes it’s impulsivity and rage behaviors. They show a lot of aggressive violence, lack of inhibition, memory loss, and signs of depression.”

McKee says that each brain the center studied showed tissue degeneration and abnormal tau protein buildup. The tau deposits occurred in the amygdala and other areas of the brain that control rage and impulsivity, likely causing symptoms such as aggression, poor impulse control, and memory loss. This helps explain the disturbing deaths of several of the NFL players who were found to have CTE. Justin Strzelczyk, a former Pittsburgh Steeler, died in a head-on car collision in 2004 as he was fleeing police after leaving the scene of a previous accident. Terry Long, another former Steeler, committed suicide in 2005 by drinking antifreeze, and several other players died from self-inflicted gunshot wounds after bouts with depression, drug abuse, or financial failure.

To help others avoid similar fates, the CSTE now has a clinical registry of over 100 athletes who are being studied longitudinally through annual neurological and neuropsychological testing, and have agreed to donate their brains for analysis after their deaths. “There is so much we don’t understand about this disease,” says McKee. “Does this happen to everybody who gets hit in the head? Does it require a certain number of injuries? Does it matter how closely spaced the injuries are? We’re trying to nail down exactly which structures seem to be affected earliest by this disorder, and the sequence of the abnormalities as they occur. The ultimate goal is to be able to identify individuals who are living with this disorder so we can treat it.”

All of the autopsied NFL players with CTE were linemen or linebackers, and McKee believes the disease is caused by the repetitive head trauma common at these positions, including sub-concussive hits (those not serious enough to trigger a concussion). Currently, the condition can only be diagnosed through autopsy, and the delay between the injuries that lead to CTE and the onset of symptoms increases the difficulty of diagnosis.

“I now get why it took so long for people to understand that smoking causes lung cancer,” says Nowinski. “It doesn’t make intuitive sense that puffing on a cigarette today makes your lungs disease ridden 40 years later. This is the same type of thing–you can get hit in the head, get up and seem fine, but then you might turn into a suicidal maniac 20 years later.”

While researchers continue exploring CTE, Nowinski is already spreading the word about its dangers. He conducts coaches clinics on concussions and CTE that include a presentation, a workbook for each coach, and a Web-based quiz they take afterward. He wants to put the entire program online so it can reach more people, and he’s working with high school state associations and public health organizations to make concussion education mandatory for coaches and players. In the meantime, he believes it’s crucial for athletic trainers to educate their athletes.

“Athletic trainers need to talk about terrible cases of CTE,” Nowinski says. “They need to show players pictures of a damaged brain and say, ‘I can protect you from this if you tell me when you think you have a head injury. If you don’t, you’re opening yourself up to this tragic condition down the road. Missing a game or two is okay. No one should trade 40 years of life for a little more glory on the field.'”

With so many unanswered questions about CTE, McKee says the take-home message from her research thus far is that post-concussion return-to-play timelines may need to be adjusted. “It’s shocking how little research has been done on the chronic effects of head trauma,” she says. “I think we’re going to find it affects a lot more people than we ever imagined, because you can get traumatic injuries in so many ways. The brain is usually capable of fully recovering from a concussion, but the recovery takes weeks. In my opinion, athletes need four weeks of rest after a concussive injury.”


Other scientific inquiries into the long-term effects of concussion reveal a potential link between these injuries and depression. A study performed at the Montreal Neurological Institute and Hospital at McGill University in Quebec suggests that post-concussion symptoms of depression reported by athletes may be caused by a neurological dysfunction in the brain.

“Until now, people thought concussed athletes probably show depression symptoms because they like to participate in their sport, and when they cannot return to play, they feel depressed,” says Alain Ptito, PhD, Associate Professor in the Department of Neurology and Neurosurgery at McGill. “But our research suggests that it’s actually part of a dysfunction coming from the brain itself.”

The study is ongoing, but the initial findings were published in January 2008 in the Archives of General Psychology based on evaluations of 56 varsity male hockey and football players from McGill. The athletes were divided into four groups: concussed and showing no depression symptoms, concussed and showing mild depressions symptoms, concussed and showing moderate depression symptoms, and a healthy control group.

The athletes filled out the Beck Depression Inventory II questionnaire (a widely used instrument for detecting the presence and severity of depression), along with a post-concussive symptom checklist. They also underwent magnetic resonance imaging (MRI) and functional MRI sessions while performing a working memory task.

“We saw that the more severe the depression symptoms reported by the athlete, the more similar the brain activation patterns were to those associated with major depression,” explains Ptito. “There is decreased activation in the dorsolateral prefrontal cortex among those who have depression after a concussion, and we don’t see this pattern in those who have a concussion without depression. We’re talking about the frontal lobes–those are the most sensitive, and most likely to receive the major impact when there is trauma to the brain.”

Functional MRI is expensive and not readily available to many athletic programs, but Ptito says there are effective, low-cost ways to identify athletes who may be struggling with concussion-induced mental health issues. He recommends neuropsychological baseline testing–a series of tests athletes perform at the beginning of the season to measure balance, memory, and reaction time that can be administered again after a concussion for comparison. He also advises screening all concussed athletes for signs of depression, administering the Beck Depression Inventory II if an athlete shows any depression symptoms, and using tests that measure frontal lobe function, such as the Wisconsin Card Sorting Test, which shows mental flexibility, and the Tower of London test, which assesses planning ability.

Coaches and athletic trainers are especially well positioned to notice any mental health issues, since they’re close enough to the athletes to catch changes in mood, attitude, and behavior. “The best way to measure emotion is through observation,” says Ptito. “Look at whether the athlete is more irritable, anxious, or sensitive to stress than they were before the concussion.”

Ptito says his findings validate scale-based tools such as the Beck Inventory and could accelerate treatment of depression. “The first line of assessment is having scales to evaluate symptom severity,” he says. “If you say, ‘I assessed this athlete and he appears to be moderately depressed,’ that may be grounds for referral to a doctor.”


By now, there’s no debate that multiple concussions are worse than one. What researchers are exploring is just how much worse.

A landmark study conducted by the National Center for Catastrophic Sport Injury Research at the University of North Carolina in 2000 surveyed 17,549 high school and college football players and found that athletes who suffered a concussion were three times more likely to suffer a second concussion within the same season than athletes who had not suffered a concussion initially. A later UNC study showed that 30 percent of college football players who suffered three or more previous concussions reported symptoms for longer than one week, while just 14.6 percent of players with one previous concussion reported symptoms lasting that long. And a study at Michigan State University found that multiple concussions lead to prolonged post-concussion symptoms, such as memory loss and slowed reaction time.

“It seems that the more concussions you get, the less force it takes for you to sustain another one, the longer it takes to recover from that concussion, and the more symptoms you have,” says Tracey Covassin, PhD, ATC, Assistant Professor in the Department of Kinesiology at Michigan State. “Once an athlete sustains a third concussion, they need to consider not playing for the rest of the season, or even permanently. The question of how many concussions is too many is constantly debated, and treatment should always be done on a case-by-case basis, but some researchers would say that three is the magic number.”

In the Michigan State study, 57 concussed collegiate athletes completed an Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) neurocognitive test, which measures verbal memory, visual memory, reaction time, and visual processing speed. The athletes performed the test within two days of their concussion and again five days after the concussion. In the latter test, athletes who had suffered their first concussion scored higher in verbal memory and reaction time than those who had suffered two or more previous concussions.

The exact effect of multiple concussions is still an unresolved issue, but these studies highlight the importance of close observation and knowing an athlete’s background. “The most important part of treating concussions has always been knowing the history of the athlete and performing a proper evaluation,” says Scott Trulock, ATC, Head Athletic Football Trainer at UNC. “We are more cautious with those individuals who have a history of concussions. We check them for persisting symptoms on a more regular basis and keep them out longer in order to prevent multiple concussions within a season or career.”


Sports with frequent, brutal collisions such as football and men’s ice hockey are most commonly associated with concussions. But female athletes face serious concussion risks as well, and recent research suggests concussion affects each gender differently.

For one study, Covassin looked at the NCAA injury surveillance data from 1997 to 2000 in lacrosse, soccer, basketball, baseball, and softball to compare injury rates between males and females. “I found that almost 14 percent of all injuries in women’s lacrosse were concussions,” she says. “In women’s soccer, over 11 percent of injuries were concussions, and basketball was at eight percent. All those percentages were higher than the rate for males in the same sport. If you take out football, females actually have a higher percentage of concussions relative to all injuries, and suffer concussions more frequently.”

In addition to different incidence rates, males and females also recover differently after a concussion. Both the University of Pittsburgh and Michigan State have conducted studies in which concussed athletes performed the ImPACT test–Michigan State studied 79 athletes across all sports, while Pittsburgh researchers worked with 234 soccer players. The Michigan State study found that females performed worse than males on visual memory tasks, while Pittsburgh found that females performed worse in reaction time tests and reported more post-concussion symptoms.

“Females don’t need to be evaluated or treated completely differently,” says Alexis Colvin, MD, co-author of the Pittsburgh study and sports medicine Fellow in the Department of Orthopedics at the University of Pittsburgh Medical Center. “But athletic trainers should be aware that females tend to have more symptoms and perform worse on the post-concussion testing when compared to their baseline testing.”

Several theories on gender differences exist, but no research has yielded definitive conclusions. “As for the higher incidence rate, one idea is that females are more likely to report their concussion,” says Covassin. “Sometimes there’s a culture in male sports to ‘play tough’ and play through it.” Colvin and Covassin agree that more research is needed, and that there isn’t enough evidence to make any concrete suggestions on holding females out longer than males or managing them differently.

However, the researchers suggest it might be helpful for females to strengthen their necks and shoulders as a preventive measure. “One theory is that males have stronger necks, so when they hit another player they are better able to absorb the impact,” Colvin says. “But even when we controlled for body mass index in our study, we still found a difference between genders.”


As research expands, so will our understanding and awareness of concussions. But the lingering uncertainty over long-term effects, repercussions of multiple concussions, and gender-specific differences only reinforces the need for a cautious and individualized approach to treatment and prevention. Educating coaches, parents, and players about the symptoms and implications of concussions remains an essential step, and sometimes it’s a major struggle.

“I once spoke at a school meeting where 50 parents showed up, but 40 of them had kids who had suffered concussions and that’s why they cared about it,” says Nowinski. “The other parents didn’t show up because apparently they didn’t think it was a problem. But those are the parents who need to be there. If their kid gets a concussion, they need to intervene right away and get the athlete proper medical attention and rest.”

Education also plays a key role in changing a culture that has long downplayed the severity of concussions. “We need to educate athletic trainers, coaches, parents, and players so athletes don’t ignore the symptoms, try to play through them, or fail to talk openly to their coach because they’re afraid of being replaced,” says McKee. “Some athletes believe a concussion is almost a badge of honor–that needs to change.”

Many in the medical and athletic communities also believe athletic programs need to rethink treatment protocols and return-to-play guidelines. There are now clinically proven, objective measures to determine when an athlete’s brain has returned to normal function, using baseline levels of neurocognitive performance. Some athletic trainers are also becoming increasingly restrictive during the recovery period.

“When you’re dealing with an injury to the brain, any type of stimulus can aggravate it, especially early on,” says Trulock. “In those first couple of days, we manage the number of meetings a concussed athlete can attend, and they certainly don’t practice. We try to control overall mental stimulation as much as we can, and that essentially helps the brain rest just as any other tissue needs to rest after injury. We allow them to progress back into normal activities, and ultimately back to practice, only once they have become totally symptom-free and have successfully completed neurocognitive and balance tests.

“We still have a long way to go in concussion treatment, but the goal is to be better off today than we were yesterday,” continues Trulock. “Rarely, if ever, do we enter an area of medical research and come up with a definitive conclusion. That’s not the nature of science. When we answer a question, we raise two more. But the most important thing is that we are improving the way we manage concussions on a year-to-year basis.”


Visit these Web sites for more information on the topics discussed in this article.

Sports Legacy Institute: www.sportslegacy.org

Center for the Study of Traumatic Encephalopathy: www.bu.edu/alzresearch/research/encephalopathy/index.html

Brain Injury Association of America: www.biausa.org

For a list of neuropsychological tests, such as the Wisconsin Card Sorting Test and the Tower of London Test, go to: www.brainsource.com/nptests.htm


The University of North Carolina is one of a handful of college football programs to outfit players with Head Impact Telemetry System (HITS) helmets, made by Riddell. These high-tech helmets, which contain six sensors, a processor, and a transmitter, record the g-force of impacts (a measure of acceleration) and wirelessly send data to a computer on the sidelines. Last season, 50 UNC players wore HITS helmets, and 90 will have them this year.

“When we begin assessing an athlete who’s reporting concussion symptoms, we check the system to see if he sustained a high-impact hit,” says Scott Trulock, ATC, Head Athletic Football Trainer at UNC. “That helps us evaluate him. For instance, if we find he didn’t have a big hit, we’ll consider whether something else might be going on. If he’s suffering from dizziness and nausea, that might be a sign of dehydration or another problem. Knowing about the hits he took helps us treat him appropriately.”

The HITS technology also helps North Carolina athletic trainers be proactive about potential head injuries. “The system is set up to notify us any time a hit occurs above a certain impact level,” says Trulock. “There have been times when we’ve checked an athlete because of that notification, and sure enough, he showed concussion symptoms. Without that system, we might not have evaluated him–if we didn’t see the hit, nothing else would tell us there might be an issue.”

Several helmet makers have joined in the fight against concussions by creating helmets that offer enhanced protection. Schutt’s ION 4D is equipped with advanced air cushioning and an energy wedge feature to absorb impact to the faceguard. Xenith’s X1 model is lined with 18 thermo-plastic air-filled shock absorbers, and Adams USA’s A4 model has an expanded polypropylene liner and a skeletal sub-structure system designed to reduce impact.

There are signs these efforts are paying off. A study by the NFL’s Mild Traumatic Brain Injury Committee published in 2006 tested five newer helmets against a traditional model through reconstructed game collisions, and showed a 10 to 20 percent lower risk for concussions with the newer helmets.


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