Thomas Hum-Hyder

On Thursday March 3^rd, Prof. Dan Lloyd, the Brownell Professor of Philosophy presented the idea that everything in the brain is “as music,” contrasting the playful expression “brain on music.” He posited the internal functional dynamics of the brain resemble the dynamics of music. He began with the analogy of an app – phenomenologically, one can look at low level and high level understandings of how apps work. On the lower level, we know that the flow of electrons is involved with someone seeing the screen on their phone; similarly, one can realize that wires and circuits form the structure of the phone that houses the app. The middle level, the code of the program or the phone, connects the lower level to the higher level. This idea of finding the middle level of our understanding of behavior is where Prof. Lloyd’s research comes in. He believes that music can be distinguished from language through a measure of “zipf-y-ness” which goes along the idea that every modern speaking language, ancient language, un-interpreted language, and even programming language, have words that appear more frequently than others, and that the plot of the most occurring words appear as a power curve. Using fMRI data from the Institute of Living as well as from the national archives, Prof. Lloyd manipulated the data that allowed for a musical tone to play as the brain scan plays out. After listening to some sample scans, I was surprised to learn that it was rather easy to distinguish between the sounds of an fMRI scan from a healthy control from a schizophrenic patient. The idea that an untrained ear could actually hear the difference in the ways in which the brains of these individuals sounds suggests that music can provide the basis for the ways in which our brains work.

Julianna Maisano

On Tuesday, February 16^th, Trinity College held a “Concussion Awareness Day”, a day with a purpose to inform students not only about concussions, but the severe consequences one can endure in the long run. The evening, the film “Head Games” was played for the Trinity community, and a discussion was held after, led by Arleigha Cook ’16, Casey Cochran, retired UConn football player, Casey Cochran, and Deb Shulansky, JD, CBIS, from the Brain Injury Alliance of CT, as the panel.

“Head Games”, directed and produced by Steve James, focuses on the concussion crisis across the United States. The plot of the film is based off of former WWE Wrestler and All-Ivy Football Player, Christopher Nowinski’s book entitled, Head Games: Football’s Concussion Crisis. After being diagnosed with post-concussion syndrome, Nowinski was not only interested to learn more about his condition, he was eager to educate parents, coaches, and athletes about traumatic brain injuries such as concussions and their potential consequences. Nowinski conducted extensive research on the prevalence and documentation of concussions endured by athletes within the National Football League (NFL). As a concussion activist, Nowinski’s book and research enable investigations to be conducted and for the film to be produced.

The documentary, details the long-term consequence NFL players endure having suffered a concussion(s), the most prevalent being chronic traumatic encephalopathy (CTE), an incurable disease in which normal brain functions are compromised by an accumulation of proteins (Head Games: The People, 2016). The disease is so detrimental, that patients often experience anxiety and depression. In certain circumstances, the psychological and physical pain the patients endure is so severe, that the patients commit suicide. Throughout the film, former NFL, NHL, and college football players and their families are interviewed. The documentary emphasized that the concussions should be taken seriously no matter how mild the symptoms may appear, and that with proper care, caution, and the right information, we can limit the amount of concussions and long-term consequences that victims endure, but can not completely eliminate them.

Immediately following the film, was a panel based discussion hosted by three individuals who have dealt with concussions first-hand. Alreigha Cook and Casey Cochran, former college athletes shared their reasons as to why they both decided to retire from their sports careers and the emotional toll that this not only took on them, but their families as well. While it was very difficult for Cook and Cochran to cease playing soccer and football, respectively, they were sure that their decisions were in the best interest of their health and well-being. Together Cook and Cochran, confirmed that things change a lot when one endures a concussion(s). Both experienced severe post-concussion symptoms such as anxiety and depression, that drastically impacted how the functioned, thought, and performed daily tasks. Cochran emphasized that players are hesitant to admit that they have received a concussion or are experiencing concussion like symptoms, as players are too invested in their game to give up and sit out. However, he notes that admitting to feeling dizzy, nauseous, or “not right” after a hard hit or bad fall, is one of the most important things an athlete can do. Deb Shulansky, a director of the Brain Injury Alliance of CT, noted times when her daughter experienced a concussion and expressed that treating concussions effectively involves adequate rest, patience, limited stimulating activities, and most importantly a strong support network that consists of family, friends, and doctors, all of which Cook and Cochran deemed were important and remain vital in their recovery process.

References

Head Games: The People. (2016). Retrieved from http://headgamesthefilm.com/about/the-people/

Khaoula Ben Haj Frej

Despite all of the attention towards concussions and preventing them, athletes continue to experience blunt trauma to the head and return to the game, particularly in football, hockey, and soccer. If a change isn’t made, a decline in participation in such sports could occur, particularly as parents steer their children away from collision sports, out of fear of brain damage and concussions.

As a major focus of his presentation, Dr. DiFiori spoke about a “vulnerable window,” a time of Increased Cerebral Vulnerability (ICV), during which one should avoid a return to the collision sport or work, or else one may experience more long-term and drastic damage (Chloe et al., 2012). After a blow to the brain, there is an increased need for energy but a lesser supply, in the form of a decrease in cerebral blood flow, normalizing only after 7-10 days. Thus, one would assume that one should wait at least that amount of time before returning to the game, to allow for normalization.

When it comes to individual cases, the hard part isn’t determining if a concussion has occurred but more so whether or not someone can return to work yet. A concussion is not a catastrophic injury in the way that other brain injuries are, although it can result in loss of brain function, loss of consciousness, or amnesia (Chloe et al., 2012). However, a misdiagnosis (or unreported case) can lead to ignoring more dangerous brain damage. Among athletic trainers and trained personnel, SCAT3 is a standardized survey of questions meant to determine if a concussion has occurred. However, not all athletes will notice or report these symptoms and 40% will go on playing, putting themselves in danger for acerbating their damage. Those who have had a concussion in the past is more likely to have another, subsequent concussion with worse and more prolonged symptoms. Often, the second concussion occurs within 10 days, which is also how long it takes to normalize cerebral blood flow, as aforementioned. Multiple studies have been made on rat models to show the impact of concussion occurring multiple times within the vulnerable window, supporting the conclusion that repeated concussions do in fact have worse and worse impacts and a new disposition for more concussions.

So, how does one decide when someone is back to normal and ready to go back to the game? Computerized neurocognitive testing is the main way in which that’s determined. It’s not as good as had been hoped; it’s faster than a complete neuropsychological battery but isn’t very reliable in terms of consistency between studies. There are too many problems with it for it to the end-all be-all approach. For example, you can easily cheat on it, since all you have to do is put forth a smaller effort before your concussion and then you look normal when concussed. Secondly, the reaction time isn’t very accurate. Someone needs to come up with something better but for now, individualized, “best practice” involves rest for a period of time before slowly training them back to the level when they can return to their sport, in a 6 step-approach (not necessarily over the course of 6 days, especially in children), according to Dr. DiFiroi and Semple et al. (2014).

He showed a lot of clips of a player hitting his head multiple times in a game, only to keep going back to play. A week later he played again and was so concussed he was knocked unconscious. A potential helpful solution is metabolic, involving implementing something like a ketogenic diet, which is being studied here at Trinity labs, or glucose supplementation. When it comes down to it however, concussions are a common problem to which a solution has not entirely been found.

Jonah Meltzer

The talk given by Dr. DiFiori was both eye opening, with regards to the research and techniques being used in modern sports medicine, and informative in terms of how these techniques are actively applied to the athletes around the NCAA. While most of his talk centered around repetitive concussive brain injury (r-CBI), I found the bits about traumatic brain injury (TBI) the most interesting. In regards to TBI, Dr. DiFiori spoke about how these r-CBI sustained by the UCLA athletes become more and more serious when they are left untreated, which can largely be due to players not reporting their injuries or coaches not wanting to take their best players out of the game. The result of multiple untreated or mistreated CBI can lead to a progressive degeneration of neurons and the brain injury known as CTE. The intersection of CTE and Dr. DiFiori’s work has manifested itself in a project on TBI spearheaded by the NCAA and the DOD that is looking to explore the effects of TBI and CBI in relation to conditions such as CTE. The DOD has taken an interest in these head trauma studies because of the similar concussive and traumatic injuries that soldiers see during combat. The larger problem with active duty soldiers is that they cannot be treated as readily for these injuries as an athlete can be on the field. Therefore, it is more likely that an active duty member of the military will sustain repeated traumas within a short period of time, traumas that are more likely to go untreated. Furthermore, it has been shown that repeated head injuries, sustained within days of one another, can be far more impactful than single traumas sustained in a similar time frame (Weil, 2014). This causes further problems for veterans because of the overlapping symptomology of post-traumatic stress disorder (PTSD) and CTE. The symptoms manifested by the two disorders have a striking similarity and often lead to a misdiagnosis, and as a result, mistreatment. When the symptoms of either disorder are manifested clinicians tend to treat for CTE first because it is a biologically occurring disorder that can be mediated with drug therapies, however, PTSD is cognitive and can be left untreated as a result of being more difficult to treat. Through the discovery of novel information with regards to CTE through studies conducted by researchers such as Dr. DiFiroi the two disorders are becoming more accessible to diagnose and treat individually, making for quicker and more complete rehabilitation of veterans.

Georgia Mergner

Dr. DiFiori presented to us a series of studies regarding repetitive mild traumatic brain injury in mice animal models and the presence of proteins released from sheared microtubules such as tau and beta amyloid. The presence of these proteins and their relation to chronic traumatic encephalopathy found in contact sports athletes, and neurodegenerative diseases such as dementia and Alzheimer’s, give rise to many questions about preventative measures and treatment. How can we protect contact sport athletes from developing CTE? Is there any way to repair the damage done from a mild traumatic brain injury, and prevent further injury from being more damaging then the first?

Dr. DiFiori’s focus on the “vulnerable window” could be the start to answering at least some of these questions. From his research on animal models studies and implementing his findings in his patient care protocol of the football players at UCLA, Dr. DiFiori and his colleagues have found that there is a window of time where re-injury could be the most damaging, if a player returns to play too soon. This is due to the window of time it takes for regular metabolic function to return to the brain. As we have learned from Brain and Behavior, the brain accounts for the use of about 25% of the body’s metabolic function. As Dr. DiFiori mentioned, a return of cerebral blood flow of normal glucose and glutamate levels takes roughly 7-10 days. With that in mind, in most of the animal model studies mentioned in the presentation, there was a peak at 3-5 days where another closed-headed injury caused heightened symptoms and increased damage to the brain; whereas a repeated injury at 7 days after the initial injury reported that histological and cognitive symptoms were no more severe than the initial injury.

This finding should be enough to pull athletes off the field at even the suspicion of brain injury. Coaches, athletic trainers and team physicians should be mindful that at collegiate and professional level, athletes are extremely competitive and less likely to report symptoms if it means staying in the game. Although 7-10 days in an athlete’s career or season may seem like forever, the risks of permanent brain damage in their later lifetime will keep them sidelined from much more. An interesting point made by Dr. DiFiori reminded me of something I had recently seen online. Besides the fact that concussions themselves should never go ignored or unreported, he mentioned that concussions could be the gateway to discovering more severe brain and spinal injuries. Recently, I watched the Tuft’s men’s lacrosse team’s documentary on their road to the national championship of their 2015 season. Their program is one of the best in the country, having won the NCAA National Championship for Division III back to back the past two years. This past season, the Jumbos’ leading scorer and returning All-American attackmen was knocked unconscious with what was believed to be a pretty high-grade concussion. After some complaining of numbness in the fingers and toes and careful observation by the athletic trainer, some testing was done and Chris Schoenhut was diagnosed with spinal stenosis. A blow to the lower back on the field could cause irreversible damage. Though his athletic career as a Jumbo has now been cut short, Chris’ future quality of life has been preserved because of this discovery. All because a trainer and a coach did not allow him to return to play after a suspected concussion and gave him the appropriate medical care he needed. As I was listening to Dr. DiFiori present, it reminded me of this discovery, and the incredible importance and responsibility that medical professionals have, at any level, to give their patients the best care possible – even if that means pulling them off the field for an extra 7-10 days.

Alex Bednarek

I thought the presentation by Dr. DiFiori on Concussion Awareness Day was very informative. Although he did not get to give us his full presentation, he focused on an extremely important aspect of concussion injury; the recovery. One of the most difficult aspects of concussive injury today for doctors and sports scientists is determining the best time for an affected athlete to return to play.

When a football or hockey player experiences a hard hit, their brains experience a phenomenon known as cerebral rotation, where the rotational force of their head, in response to the hit, causes axons to tear in a process known as axonal shearing. The shearing of the axon can cause excitotoxicity, where a series of chemicals, normally confined by the axon, are released into the cytoplasm of the brain. The tearing of the axons and release of chemicals can result in significant cognitive impairment. Dr. DiFiori alluded to the fact that some players recover quicker than others, but most concussion victims do not see a significant improvement in their symptoms until 8-10 days after their incident, as he also states in the article.

After hearing that the recovery time is usually 8-10 days after the incident, I thought that, if a player were to get a spinal tap, their results would show a high amount of chemicals in CSF. These chemicals would come from the tearing of the axon and the breaking of the microtubule filaments, which would release damaging tau proteins. This process would also alert the astrocyte cells of the nervous system, which would release S100B molecules, in addition to the cytokines, APP and TDP-43 molecules being released. The release of tau proteins and glutamate causes neuronal cell death. In one of Dr. DiFiori’s articles titled, “A pediatric perspective on concussion pathophysiology”, it is stated that the release of glutamate and other excitatory neurotransmitters causes an ionic flux. Essentially, NMDA and AMPA receptors are activated by the neurotransmitters causing a massive calcium and sodium influx into neurons and surrounding glia. This ionic imbalance can also facilitate the degradation of the axons.

I think the fact doctors and athletic trainers are cracking down on coaches who want to put their injured players back in the game is a good thing for the safety of the players. Coaches and doctors, like the ones at UCLA, should be working cooperatively to deduce not only when their players get concussions, but also when the best time is for them to return to play. Watching the video footage of the University of Washington quarterback getting hit and still playing was a perfect example of what not to do when faced with a situation like that. The first hit that he sustained was quite alarming, as he tried to get up and fell down 3 times, all the while holding his head. It was quite alarming watching him attempt to stand, but his limbs would simply crumble beneath him. It is as if his whole IPO (Input Processing Output) was not functional. He knew he was trying to stand up, but through a confusion of stray neural processing, most likely in the cerebellum and motor cortex, he was not able to properly stand.

Hopefully, through the use of new fMRI technology and various other imaging techniques, neuroscientists will be able to convince coaches, players and families of players of the dangers of concussions. If a recently concussed player gets a concussion, it can be assumed that his brain scan in an fMRI may show signs of neuronal cell death. These images of damaged brains should cause players, families and football fans to really consider helmet safety and TBI. Dr. DiFiori’s talk should be nationally distributed by the NCAA to warn players of what can happen if they get a concussion and worse, lie about the symptoms

Julianne Maisano

On Tuesday, February 16, 2016 Dr. John P. DiFiori, Chief of the Division of Sports Medicine at UCLA, held a lecture entitled, “The Vulnerable Window in Concussion: A Challenge in Determining Return to Play”. Dr. DiFiori discussed the process by which a concussion is diagnosed on the sideline of a game, the pathophysiology of a concussion, and some of the most recent research studies that have examined the consequences of concussions on a cellular and physiological level. In his lecture, Dr. DiFiori the average time (10 days) that it takes for a collegiate athlete’s concussion symptoms to resume, the fact that most athletes are not willing to report a concussion, and that one is most vulnerable to endure long-term cognitive function problems if they receive a second concussion three days after they receive their first one. However, one of the most important things he mentioned was protocol that details the length of time a player should sit out before they are allowed to return to play (RTP), a process that is not only vital to the patient’s immediate well-being, but for their long-term well-being as well.

A concussion can be defined as a traumatic brain injury induced by a disruption in the anatomical structures and pathophysiological processes of the brain (Harmon et al., 2013). Classified as a traumatic brain injury (TBI), concussion severity can range from a mild to severe depending upon the patient’s symptoms. According to the Center for Disease Control (CDC), approximately 1.6-3.2 million people endure concussion a year within the United States, and of those concussions endured, most as classified as mild (Choe et al., 2012). While many people are under the impression that concussions are primarily caused by direct head to head contact, this predisposed notion is not completely true. Dr. DiFiori mentioned, that while most concussions occur as a result of physical contact, most concussions are a result of head to ground or wall contact (DiFiori, 2016).

According to Dr. DiFiori, there is a decline in participation in youth football, as children as being swayed away from participating in contact sports. This decision can be attributed to the increase of knowledge about the symptoms, severity, and long-term effects of concussions, such as chronic traumatic encephalopathy (CTE). It is known that children’s brain heals more slowly than a mature adult brain. Children’s skulls are not proportional to their neck, which makes them susceptible to concussions. This lack of maturity, allows for the brain to move around significantly during a collision due the weight of the head overwhelming the neck. Likewise, a child’s brain is not completely myelinated and numerous neuronal connections and synapses have yet to be formed. When the brain becomes concussed, it endures an electrical shock and smacks against the inside of the skull. This rapid movement causes axons to tear and disrupt numerous neural connections. As a result, an influx of the protein tau is found within the axons is released into the cerebral spinal fluid (Semple et al., 2015). On average, it takes collegiate athlete cerebral blood flow between nine and ten days to normalize. This is not to say that it takes approximately ten days for all athletes to get back on the field and return to play, but this time point gives the brain a longer rest time and allows it to reset itself, something which is found to be longer in children (DiFiori, 2016).

Dr. DiFiori also discussed the vulnerable window, a period of time after someone receives a concussion, that if they continue to play and received another concussion are at a greater risk to encounter long-term cognition issues, such as chronic traumatic encephalopathy (CTE), as well as psychological disorders. Serious long-term consequences such as CTE could result in depression and/or anxiety, and could possible lead athletes to commit suicide. Dr. DiFiori detailed the various consequences of an athlete retuning to play before they are physically, mentally, and emotionally ready. Subsequently, to explained the differences in and importance of neurological tests prior to athletes beginning a season to determine their baseline score, which will be used to evaluate the athlete’s progress while they have a concussion and post concussion. To express the significance of the vulnerable window, Dr. DiFiori discussed Huang et al. (2013) research study, which analyzed the impact of concussions on animal models and found that of the time points at which concussions were given to mice after they received their first surgery, three days post concussion number one resulted in the worst long-term cognitive functions for the animal.

To conclude his lecture, Dr. DiFiori stated that the best practice for treating a concussion is to remove an athlete immediately from a sporting event if they are expressing concussion symptoms, properly evaluate their symptoms and document them, and to inform the athlete how to rest while they have concussion, as well as to limit their use of light and brain stimulating devices and activities. Dr. DiFiori mentioned that it is important to gradually integrate stimulation while treating a concussion, and to always keep in mind the best interest of the athlete for both the short-term and most especially the long-term, when developing a treatment plan.

References

Choe, M. C., Babikian, T., Difiori, J., Hovda, D. A., & Giza, C. C. (2012). A pediatric perspective

on concussion pathophysiology. Current Opinion in Pediatrics, 24(6), 689-695.

DiFiori, J. P. (2016, February 22). The Vulnerable Window in Concussion: A Challenge in

Determining Return to Play. Lecture presented at Concussion Awareness Day in McCook Auditorium, Hartford, CT.

Harmon, K. G., Drezner, J., Gammons, M., Guskiewicz, K., Halstead, M., Herring, S., . . . Roberts,

18. (2013). American Medical Society for Sports Medicine Position Statement. Clinical Journal of Sport Medicine, 23(1), 1-18.

Semple, B. D., Lee, S., Sadjadi, R., Fritz, N., Carlson, J., Griep, C., . . . Noble-Haeusslein, L. J.

(2015). Repetitive Concussions in Adolescent Athletes – Translating Clinical and Experimental Research into Perspectives on Rehabilitation Strategies. Frontiers in Neurology Front. Neurol., 6, 1-16.

Thomas Hum-Hyder

Last week, Dr. John DiFiori, the head physician of the University of California at Los Angeles’s Bruins football team came to Trinity to speak of his work with athletes with concussions and best to approach the idea of return to play. What was most striking about Dr. DiFiori’s talk was the apparent discontinuity between the rules regarding when players are to be taken out of a game and what actually happens. Research out of his lab and colleagues at UCLA seem to suggest that return to play is most acceptable after a nine-day period, as it seems as though the risk of sustaining another concussion would be reduced. However, in a video that Dr. DiFiori showed, it showed a quarterback sustaining repeated blows to the head throughout the second half of play after having a hard impact in the first quarter, which left him clearly dazed. While official policies seem to indicate that coaches are required to take players out of games after there is a blow to the head that looks as though it could result in a concussion, it is clear that these general guidelines tend to not occur, due to pressures from higher ups. When the incidence of chronic traumatic encephalopathy in on the rise, most prevalently in individuals who sustained many blows to the head during playing careers, it is incredibly worrying that coaches and sports organizations tend to prefer a potential win over a lifetime of degenerative brain damage.

Morgan Williams

John DiFiori, Professor at UCLA and Head Team Physician of their Department of Intercollegiate Athletics gave a challenging glimpse into the world of sports-related concussions. One profound fact Professor DiFiori opened with was that there is legislation in all fifty states surrounding concussion management- especially as it pertains to high school students (DiFiori, 2016). Although I am not a huge sports fan in general, my immediate understanding was that concussions are both serious and common. What exactly is a concussion? Essentially a subset of Traumatic Brain Injury Brain Injury (Semple et al., 2015). The pathophysiology of this condition includes the release of neurotransmitters, and irregular ion fluxes with and efflux of potassium(K) and an influx of calcium (Ca) (DiFiori, 2016). There is also a decline in the brain’s ability to utilize glucose which leads to a lessened cerebral flow (DiFiori, 2016). Symptoms include headache, fatigue, nausea, fatigue, balance problems, anxiety, difficulty concentrating, and more (Semple et al., 2015). Despite how common and serious this injury is, there is still a surprising amount on this subject still being learned, and there are still many challenges. One of those Professor DiFiori shared with us is the actual reporting of concussions (or potential concussions) is less than perfect. Sometimes athletes do not recognize the symptoms, and other times they do, they hide them because they want to continue playing. A lot of responsibility is notably on the coaches as well. In one of the video clips of a past UCLA football game, the audience was shown a prime example of a player who noticeably hit his head on the ground during the game, not being taken on the sidelines and checked out, but continuing to play. Looking at the player’s eyes it was obvious that he was fighting to remain focused after the blows, at one point visibly shaking his head and blinking his eyes as to ward of the haze of confusion after he was knocked to the ground. The risky part in loving the the sports these athletes play is that in wanting to remain in play, and win, acknowledging a concussion may fall lower on the priority list. The bottom line is that after a concussion the brain is believed to be in a much more vulnerable state. The question for these players is when is this state improved and when can the player return to the game?

Despite how common and serious this type of injury is, especially in sports there is still much to be learned about when playing can definitively be resumed for the player. In describing the return to play (RTP) protocol, Professor DiFiori discussed the present 6 best practice steps and then described some different initiatives being used. This includes graded exercises. The problem with these approaches is that the tests are not definitive. DiFiori has even seen players who ‘dumb themselves down’ when taking the initial assessment as to offset their feedback in the case that they have a concussion and are given the assessment again (DiFiori, 2016). There is much believed to be at risk in a player returning to play before they have properly healed. Current research supports that if a second concussion happens within 1-3 days the cognitive function was significantly worse and the individual was more likely to have long term learning impairments. If the second concussion happened after 10 days (for an adult athlete), it is as if they are experiencing a concussion for the first time (Choe et al., 2012). Yet there is no science that backs a definitive 10-day rule for athletes with concussions. Yet the RTP protocol as it is, is still a challenge. First and fore most it is based on the two “yet to be proven concepts” (Choe et al., 2012) mentioned above (although it is it is increasingly supported by clinical and laboratory research as mentioned throughout this paper). That is, that a concussed individual is more likely to get another concussion, and repeat injuries within a short window may cause cumulative brain damage (Semple et al., 2015). While rest is the first step in this protocol, and seems the obvious choice, there is evidence that using rest to promote CNS recovery in a previously active athlete may actually cause withdrawal and growth of trophic factors. A study on rats yielding the ultimate finding (when transferred to brain –injured humans) that rest may create a situation where BNDF expression is low causing and environment where greater neural damage is possible (Semple et al., 2015). All in all, Professor DiFiori’s talk gave a very in-depth update on the current state of concussion management in athletes. One that, along with the readings, illuminated the great strides and findings that have allowed for increased and accurate recognition and treatment of the injury, and one that illuminated the great strides still in play. It is apparent that we are only just beginning to fully appreciate how concussions might influence the structural integrity and functioning of the brain. All in all, there is still much to be learned about the intricate and magnificent brain, in hopes of definitively pinpointing a concussion and its full recovery as to build a more definitive RTP protocol for the athletes that love these sports despite their risks.

References

Choe, Meeryo C., et al. “A pediatric perspective on concussion pathophysiology.” Current Opinion in Pediatrics 24.6 (2012): 689-695.

DiFiori, J. (2016, February 16). The Vulnerable Window in Concussion: A Challenge in Determining Safe Return To Play. Lecture
presented in McCook Auditorium, Hartford, CT.

Semple, Bridgette D., et al. “Repetitive concussions in adolescent athletes–translating clinical and experimental research into perspectives on rehabilitation strategies.” Frontiers in neurology 6 (2015).