ATHLETE CONCUSSION, DEPRESSION, INJURIES, STATS

“Charlie Pell, a Bear Bryant disciple, and assistant to Bradshaw at UK from 1965-1969 suffered with severe depression. Pell made a public service documentary about his depression for the state of Alabama. His documentary was a very noble achievement and a source of public information.

“Many football players and coaches suffer mental and physical illness. Ofetn the mental and physical illness is the result of physical and psychological abuse by other coaches. Multiple head injuries have been shown to result in severe mental illness to players later in their lifetime.

“A traumatic brain injury is characterized by loss of consciousness, confusion, amnesia for the events, and other neurological signs. Concussion often results later with loss of mental functioning and memory, migraine, seizures, dizziness, and depression.

“An investigation of the association between prior head injury and the likelihood of being diagnosed with clinical depression among retired professional football players with prior head injury exposure. Depression is the most cited psychological disturbance after traumatic brain injury, with prevalence rates from 6% in cases of mild traumatic brain injuryto 77% in more severe TBI] within the first year after injury. Retired players reporting three or more previous concussions (24.4%) were three times more likely to be diagnosed with depression; those with a history of one or two previous concussions (36.3%) were 1.5 times more likely to be diagnosed with depression. 4.[ 4. Recurrent Concussion and Risk of Depression in Retired Professional Football Players MedScape Posted 06/19/2007 Kevin M. Guskiewicz; Stephen W. Marshall; Julian Bailes; Michael McCrea; Herndon P. Harding Jr; Amy Matthews; Johna Register Mihalik; Robert C. Cantu]

“Concussions can trigger a chemical chain reaction in brain neurons that leaves an athlete disoriented, unconscious, or dead. They can also impair learning over a period of years.

“Barret Robbins, Oakland Raiders Pro Bowl center, suffered from severe depression, a mental illness. “The demons running loose inside Barret Robbins’ head put theplayer in a San Diego hospital on Super Bowl Sunday”. The physical power of his 6-foot-3, 320-pound body was no match for the illness. Like anyone else, athletes can be ravaged by the emotional and physical toll that comes with depression. Worse, athletes’ reluctance to deal with their condition, the jock environment that makes them ashamed of their perceived “weakness,” and physical side effects brought on by medication add up to the most troublesome foe they will ever face.”

“As athletes, we are taught to be tough,” said former NHL all-star Pat LaFontaine, who has battled depression. “You get up and shake it off. But you can’t do that with depression. For me, the harder I tried, the worse it got.” Spiraling into shadows so dark she thought she’d never get out, former U.S. Olympic diver Wendy Williams once collapsed in front of her refrigerator, overwhelmed by something as simple as deciding what to eat. She quit getting into her car for fear she would drive off a cliff to escape her misery. 78.[ 78. Fearsome opponent By Patrick SaundersDenver Post Sports Writer Monday, March 10, 2003 – Bipolar disorder]

“Harry Carson, middle linebacker with the New York Giants was a celebrated defensive football player, smart and agile, selected for the Pro Bowl even during years his team couldn’t eke out a winning season. Above all, he was known for aggression. After a collision a dazed, Carson dusted himself off and walked back into the Giants’ huddle—and as he stood holding his teammates’ hands, everything went black. He didn’t faint. He didn’t stop playing. For a few minutes, though, he found himself unable to interpret his coach’s signals from the sidelines. He couldn’t call the next play, as the middle linebacker is expected. Blackouts like these were becoming familiar sensations for Carson. Over 13 seasons, he estimates he received between 15 and 18 concussions.

“It was only toward the end of his career that he began to exhibit the cumulative effects of all these hits, signaling what his doctors would later call postconcussion syndrome. Carson developed headaches and muscle twitches. He grew sensitive to bright lights and loud noises, making it difficult for him to sit in a busy restaurant or do a television interview. He’d lose track of time: Until recently, athletes like Carson were of little interest to scientists. With dozens of football fatalities each year in the 1960s, particularly at the high school level, researchers were much more concerned with on-field catastrophes. “When someone dies, that catches everyone’s attention,” says neurosurgeon Robert Cantu, medical director of the National Center for Catastrophic Sports Injury Research. “It’s not surprising that fatalities in football have been tracked since 1931.”

“Thanks to better protective equipment and safer coaching techniques, football deaths have now dropped to single digits each year. The decline has allowed scientists to focus on more subtle traumas, and concussions are chief among them. Neurosurgeons have shown that even a minor ding can trigger a neurological cascade that can eventually cause cognitive dysfunction and mental illness. Among retired football players who have sustained three or more concussions, 20 percent have been diagnosed with clinical depression—more than three times the rate of players who never got a concussion.

“Almost half of those are taking antidepressant medications, and most report that the condition impedes their normal daily activities, such as shopping for groceries and going to work.At the UCLA Brain Injury Research Center, neuropsychologist David Hovda has studied the cascade of these injuries. An injured athlete may be oblivious to the neurochemical cascade inside his brain. “You can see a broken arm,” says Carson. “You can see a torn ligament in the knee. But with a concussion, you don’t see it.” The effects show up in statistical research.

“In 2001 Kevin Guskiewicz, research director of the Center for the Study of Retired Athletes at the University of North Carolina at Chapel Hill was surprised by the depression statistics. Athletes with no concussions had a lifetime diagnosis rate of 6.6 percent. That is about the same as the general male population. Once they suffered three or more traumas, however, the rate skyrocketed to 20.2 percent. The depressions, can interact with other health problems to destroy the former athletes’ lives. The depressions have a snowball effect. The football player is retired from football, overweight, has musculoskeletal problems like sore knees, ankles, hips, not exercising. and life begins to go downhill.” 79.[ 79. Discover Science, technology, the future Lights Out Can contact sports lower your intelligence? by Barry Yeoman December 3, 2004]

“Many other sports other than American football are plagued by concussions. Soccer, hockey and baseball are examples. Matser and Lezak compared the results of swimmers and runners and found the soccer players were three to four times more likely to show deficits in memory and planning skills. The more concussions players suffered, the lower their scores on three of the 16 tests. Lezak is unsurprised. “I know what happens when you bat on the brain,” she says. “Given what we know about boxing, it would have been surprising if we hadn’t found anything. In soccer, people are punishing themselves in much the same way boxers do.”
[Plowline, Coach, Mules and 100 Yards of Cotton, http://www.cappaa.com/category/plowline-coach-mules-100-yards-of-cotton

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“Abstract: Chronic traumatic encephalopathy (CTE) has been linked to participation in
contact sports such as boxing and American football. CTE results in a progressive decline of
memory and cognition, as well as depression, suicidal behavior, poor impulse control,
aggressiveness, parkinsonism, and, eventually, dementia. In some individuals, it is associated
with motor neuron disease, referred to as chronic traumatic encephalomyelopathy,
which appears clinically similar to amyotrophic lateral sclerosis. Results of neuropathologic
research has shown that CTE may be more common in former contact sports athletes than
previously believed. It is believed that repetitive brain trauma, with or possibly without
symptomatic concussion, is responsible for neurodegenerative changes highlighted by
accumulations of hyperphosphorylated tau and TDP-43 proteins. Given the millions of
youth, high school, collegiate, and professional athletes participating in contact sports that
involve repetitive brain trauma, as well as military personnel exposed to repeated brain
trauma from blast and other injuries in the military, CTE represents an important public
health issue. Focused and intensive study of the risk factors and in vivo diagnosis of CTE will
potentially allow for methods to prevent and treat these diseases. Research also will provide
policy makers with the scientific knowledge to make appropriate guidelines regarding the
prevention and treatment of brain trauma in all levels of athletic involvement as well as the
military theater.”
[2011 by the American Academy of Physical Medicine and Rehabilitation
Vol. 3, S460-S467, October 2011Long-term Consequences of Repetitive Brain Trauma: Chronic Traumatic Encephalopathy Robert A. Stern, PhD, David O. Riley, BS, Daniel H. Daneshvar, MA, Christopher J. Nowinski, BA, Robert C. Cantu, MD, Ann C. McKee, MD
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The American Academy of Pediatircs report notes that a return to sports and physical activity should not occur the same day as a concussion. Return to sports and physical activity requires a progressive exercise program, a complete absence of symptoms, successful completion of a standardized neuropsychological test, and continuing evaluation for any recurring signs or symptoms. The recovery for pediatric and adolescent athletes is generally longer than for older athletes.
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“In March 2013, the American Academy of Neurology (AAN) updated its 1997 guidelines on the evaluation and management of sports concussion. A major change is the removal of return-to-play recommendations. The current recommendation for athletes who have sustained a concussion is immediate removal from play. Return to play should not be allowed until after assessment by a healthcare professional. Young athletes should be managed even more conservatively; their symptoms and neurocognitive performance take longer to improve after a concussion.

“Highlights from the revised recommendations include the following[15, 47] :
• There is no evidence that medication improves recovery after concussion
• The risk for concussion is greatest in football and rugby, followed by hockey and soccer; for young women and girls, the risk is greatest in soccer and basketball
• An athlete who has a history of 1 or more concussions is at greater risk for being diagnosed with another concussion
• The first 10 days after a concussion appears to be the period of greatest risk for being diagnosed with another concussion
• Evidence suggests that use of helmets may prevent concussion versus no helmet, but there is no clear evidence that one type of football helmet can better protect against concussion over another kind of helmet
• Licensed health professionals trained in treating concussion should look for ongoing symptoms, history of concussions, and younger age in the athlete
• Risk factors linked to chronic neurobehavioral impairment in professional athletes include prior concussion, longer exposure to the sport, and having the ApoE4 gene
• Symptom checklists, the Standardized Assessment of Concussion (SAC), neuropsychological testing (paper-and-pencil and computerized), and the Balance Error Scoring System may be helpful tools in diagnosing and managing concussions but should not be used alone for making a diagnosis
• Although an athlete should immediately be removed from play after a concussion, there is insufficient evidence to support absolute rest after concussion
[Concussion Treatment & Management by David T Bernhardt, MD; Chief Editor: Sherwin SW Ho, MD Medscape, Oct 7, 2013]

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“Concussion is defined as any transient neurologic dysfunction resulting from a biomechanical force. Loss of consciousness is a clinical hallmark of concussion but is not required to make the diagnosis. Other symptoms include confusion, disorientation, unsteadiness, dizziness, headache, and visual disturbances. These postconcussive deficits occur with minimal detectable anatomic pathology and often resolve completely over time, suggesting that they are based on temporary neuronal dysfunction rather than cell death. Neuronal dysfunction can occur due to ionic shifts, altered metabolism, impaired connectivity, or changes in neurotransmission. Thus, a complete understanding of the phenomenon of concussion requires knowledge of the underlying pathophysiology of this injury. In this article, we will review the neurometabolic events following experimental concussive brain injury and then apply this knowledge to specific scenarios pertinent to sport-related concussion.

“Cerebral concussion is followed by a complex cascade of ionic, metabolic, and physiologic events. The earliest changes are an indiscriminate release of EAAs and a massive efflux of K+, triggering a brief period of hyperglycolysis. This is followed by more persistent Ca2+ influx, mitochondrial dysfunction with decreased oxidative metabolism, diminished cerebral glucose metabolism, reduced CBF, and axonal injury. Late events in the cascade include recovery of glucose metabolism and CBF, delayed cell death, chronic alterations in neurotransmission, and axonal disconnection. Clinical signs and symptoms of impaired coordination, attention, memory, and cognition are manifestations of underlying neuronal dysfunction, most likely due to some of the processes described above. It is difficult to match clinical signs with specific underlying physiologic derangements, and guidelines permiting return to play only after resolution of all motor and cognitive deficits are a minimal precaution. There is recent evidence that even relatively asymptomatic (GCS 13-15) patients may demonstrate depressed glucose metabolism on PET imaging following TBI, reinforcing the need for meticulous clinical assessment. Further study will reveal more details of the time course for this neurometabolic cascade. This will eventually permit improved clinical monitoring of posttraumatic pathophysiology in actual patients, including variables such as cerebral glucose metabolism, blood flow, neuronal activity, and even molecular changes.

“Traumatic injury to the developing brain may lead to long-lasting changes in cognitive potential, perhaps even with little evidence of an initial deficit. Children and adolescents who sustain a concussive brain injury should be closely monitored over time for the later appearance of neurobehavioral abnormalities.

“Repeated injury within a particular time frame can lead to a much larger anatomical or behavioral impairment than 2 isolated injuries. The second injury may be obvious, such as a repeated concussion, hypoxia, or seizure, or it may occur in the form of premature activation or overstimulation of the injured brain. An awareness and understanding of postconcussive pathophysiology will help in determining the best time course for return to practice and return to play.
[J Athl Train. 2001 Jul-Sep; 36(3): 228–235. The Neurometabolic Cascade of ConcussionChristopher C. Giza and David A. Hovda]
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Conclusion: “Professional football players self-reporting concussions are at greater risk for having depressive episodes later in life compared with those retired players self-reporting no concussions.
[Nine-Year Risk of Depression Diagnosis Increases With Increasing Self-Reported Concussions in Retired Professional Football Players by Zachary Y. Kerr, MPH, MA*,†Stephen W. Marshall, PhD*,†Herndon P. Harding Jr, MD§ and Kevin M. Guskiewicz, PhD, ATC Am J Sports Med October 2012 vol. 40 no. 10 2206-2212]
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Abstract

“Objective: To determine whether correlates of white matter integrity can provide general as well as specific insight into the chronic effects of head injury coupled with depression symptom expression in professional football players.

“Method: We studied 26 retired National Football League (NFL) athletes who underwent diffusion tensor imaging (DTI) scanning. Depressive symptom severity was measured using the Beck Depression Inventory II (BDI-II) including affective, cognitive, and somatic subfactor scores (Buckley 3-factor model). Fractional anisotropy (FA) maps were processed using tract-based spatial statistics from FSL. Correlations between FA and BDI-II scores were assessed using both voxel-wise and region of interest (ROI) techniques, with ROIs that corresponded to white matter tracts. Tracts demonstrating significant correlations were further evaluated using a receiver operating characteristic curve that utilized the mean FA to distinguish depressed from nondepressed subjects.

“Results: Voxel-wise analysis identified widely distributed voxels that negatively correlated with total BDI-II and cognitive and somatic subfactors, with voxels correlating with the affective component (p < 0.05 corrected) localized to frontal regions. Four tract ROIs negatively correlated (p < 0.01) with total BDI-II: forceps minor, right frontal aslant tract, right uncinate fasciculus, and left superior longitudinal fasciculus. FA of the forceps minor differentiated depressed from nondepressed athletes with 100% sensitivity and 95% specificity. “Conclusion: Depressive symptoms in retired NFL athletes correlate negatively with FA using either an unbiased voxel-wise or an ROI-based, tract-wise approach. DTI is a promising biomarker for depression in this population. [Depressive symptoms and white matter dysfunction in retired NFL players with concussion history by Jeremy Strain, BS, et.alMay 24, 2013, journal of Neurology July 2, 2013 vol. 81 no. 1 25-32] __________________________________________________________ "Concussion has been in the medical lexicon since Hippocrates,1 and widespread viewing of sports concussion is now commonplace. This mildest form of traumatic brain injury (TBI) has obvious acute effects, but motor symptoms seem to abate quickly as the concussed player leaves the contest. The prompt return to baseline in most sports concussions could be considered as evidence for the transient nature of the injury, with the brain's homeostatic equilibrium temporarily disrupted and then restored, but this view may be changing. With 1.6–3.8 million sports-related concussions annually in the United States (http://www.cdc.gov/ncipc/tbi/Physician_Tool_Kit), the possible long-term consequences of concussion clearly merit attention. [When is a concussion no longer a concussion? byErin D. Bigler, PhD, Ellen Deibert, MD and Christopher M. Filley, MD (Journal of) Neurology July 2, 2013 vol. 81 no. 1 14-15] ____________________________________________________ Conclusions: “The results suggest that athletes having sustained concussions in early adulthood may be at a higher risk for developing depression as they age compared to the general population (particularly cognitive symptoms of depression). [Ameican Acadamey Nenuroloby 65th ANNUAL MEETING ABSTRACT by Rachel Seroka, Angela Babb, JANUARY 16, 2013] ________________________________________________________________ “Each year, an estimated 38 million children and adolescents participate in organized sports in the United States.(1) In addition, 170 million adults participate in physical activities, including sports.(2) Table 1 presents the number of high school and collegiate athletes participating in each sport from the 1982–83 season through the 2007–08 season.(3) Many of these activities are associated with an increased risk of traumatic brain injury (TBI).(4) In the United States, an estimated 1.7 million people sustain a TBI annually, associated with 1.365 million emergency room visits and 275,000 hospitalizations annually with associated direct and indirect costs estimated to have been $60 billion in the United States in 2000.(5, 6) Additionally, the Centers for Disease Control estimates that 1.6 to 3.8 million concussions occur in sports and recreational activities annually.(7) However, these figures vastly underestimate total TBI burden, as many individuals suffering from mild or moderate TBI do not seek medical advice.(5, 7) “A concussion is a TBI induced by an impulsive force transmitted to the head resulting from a direct or indirect impact to the head, face, neck, or elsewhere.(8) These concussions may present with a wide range of clinical signs and symptoms, including physical signs (e.g., loss of consciousness, amnesia), behavioral changes (e.g., irritability), cognitive impairment (e.g., slowed reaction times), sleep disturbances (e.g., drowsiness), somatic symptoms (e.g., headaches), cognitive symptoms (e.g., feeling “in a fog”), and/or emotional symptoms (e.g., emotional lability).(9) Because these impairments in neurologic function often present with a rapid onset and resolve spontaneously, many concussions are neither recognized by athletes nor observed by coaches or athletic trainers.(10-13) As a result, a large proportion of concussions are simply unreported. “This issue is further complicated by the fact that many coaches, athletic trainers, and other sports medicine professionals do not properly utilize current guidelines for concussion assessment and management.(14, 15) To help educate these professionals on proper concussion identification and treatment, the Centers for Disease Control and Prevention (CDC) launched the Heads Up program, which includes educational materials aimed at youth coaches, high school coaches, parents, athletes, school administrators, and medical professionals. These resources have been shown to improve high school coaches' knowledge regarding how to evaluate and properly manage concussions.(16, 17) In part due to awareness measures like these, the number of concussions reported to the National Collegiate Athletic Association (NCAA) through its Injury Surveillance System (ISS) showed an average annual increase of 7.0% from the 1988–89 through 2003–04 seasons (P < .01).(18) Table 2 displays the concussion rate in each sport from the 2005–06 NCAA ISS database. Table 3 displays the rate of concussion stratified into high school school and collegiate play, and compares concussion rate in practice versus competition. "Additionally, the concussion rate observed through the ISS doubled from 0.17 per 1000 athlete exposures (A-E, with an exposure defined as one athlete playing in one game or practice) in 1988–89 to 0.34 per 1000 A-Es in 2003–04.(18) This increased rate of concussion may also be due in part to an increase in the true rate of concussion over the past several decades. However, even with new resources, proper identification of concussion remains a problem.(16) Many of these concussions could be prevented outright with proper medical care and safety precautions, such as implementation of safer rules, proper conditioning, and standardized coaching techniques. Football: “Of all sports played in the US, American football is the sport associated with the greatest number of traumatic brain injuries, but it also has the largest number of participants. As shown in Table 1, between the 1982–83 season and the 2007–08 season, a total of 35,641,573 high school athletes and 1,929,069 collegiate athletes competed in football.(3, 19) For purposes of this article, an athlete is defined as one player playing one season. Because many high school and college players play multiple years of football, the number of unique participants is much lower. However, that data is not available. Currently, the National Federation of State High School Associations estimates that there are approximately 1,500,000 high school, junior high school, and non-federation school football participants. The NCAA, the National Association of Intercollegiate Athletics, and the National Junior College Athletic Association estimate that there are currently 75,000 collegiate football participants, including estimates of athletes at schools not associated with any national organization. 225,000 participants are estimated to compete in fully padded, organized, non-professional football (sandlot) and professional football. Combined, these figures indicate that approximately 1,800,000 total athletes participated in football in the United States during the 2009 football season.(19) “Injuries : Because of the aforementioned difficulties in examining concussion specifically, total incidence of catastrophic head injuries may be a better comparator for injury trends over time. Catastrophic head injury is defined as a head injury caused by direct contact during competition resulting in a fatal, nonfatal permanent, or serious nonpermanent injury. Since the 1982–83 season, there have been 133 football players with incomplete neurological recovery from catastrophic head injury. 120 of these injuries occurred in high school athletes, eleven occurred in college participants, two occurred in sandlot players, and none occurred in professional football players. In 2009, all nine cerebral injuries with incomplete recovery were in high school athletes.(20) “Although there have been significant reductions in these injuries following rule changes in the 1970s, the rate of head injuries has been increasing in recent years. Over the ten-year span from 2000 to 2009, there was an average of 6.2 cerebral injuries annually with incomplete recovery in football. The prior ten years averaged 4.5 cerebral injuries annually. The ten cerebral injuries in 2008 and nine in 2006 and 2009 were the highest incidences since 1984.(20) “Because concussion awareness and diagnosis has changed significantly over the past few decades, there is wide variability in the literature on the rate of concussion in football athletes. One study, evaluating concussions reported to medical professionals over a three-season span from 1995 to 1997, found that high school football players had a rate of 3.66 concussions per 100 player-seasons, meaning that there were 3.66 concussions every season for every hundred athletes.(21) However, another study, a post-season retrospective survey of 233 football players after the 1996–97 season, found that 110 (47.2%) reported having experienced at least one concussion. Multiple concussions were noted in 81 (34.9%) of the athletes.(22) Additionally, the NCAA ISS found a concussion rate of 0.37 per 1000 A-E (95% CI = 0.36, 0.38) from the 1988–89 season through the 2003–04 season.(18) Recent studies indicate even higher rates of reported concussion in football players. In one study, examining the concussions reported by 425 athletic trainers from 100 US high schools and 180 US colleges, the rates of concussion were compared between high school and collegiate athletes. The high school athletic trainers reported 201 concussions over the 2005–06 season, which yielded a concussion rate of 0.21 per 1000 A-E in practice and 1.55 concussions per 1000 A-E in competitions. Together, these averaged a rate 0.47 per 1000 A-E overall. As expected, each game carries a statistically significant increased risk of concussion with an injury proportion ratio (PR) of 1.39 (95% confidence interval (CI) = 1.01, 1.91). 245 concussions were reported in the collegiate athletes, resulting in a concussion injury rate of 0.39 per 1000 A-E in practice, and a rate of 3.02 concussions per 1000 A-E in competitions (resulting in an overall rate of 0.61 per 1000 A-E).(23) These results indicate a statistically significant increase in rate of diagnosed concussion between high school and collegiate athletes. Because college athletes tend to have greater access to and more interaction with medical professionals, the increase may be due to medical infrastructure rather than differences in the number of actual concussions sustained. “The same study evaluated the types of collisions that resulted in concussions and found that tackling and being tackled were responsible for 67.6% of the concussions observed in these football players.(23) Concussive impacts may produce different signs based on the age of the athlete. Although the high school and college groups did not differ in presentation of symptoms such as confusion or retrograde amnesia, college athletes did experience a high rate of loss of consciousness (34%) compared to the high school athletes (11%). Despite this lower rate of loss of consciousness, studies have shown that high school athletes who have experienced a concussion show worse recovery, in the form of prolonged memory dysfunction, as compared to concussed collegiate athletes. College athletes, despite having more concussions throughout the season, typically recover and match control subjects by day 3 following the concussive blow. However, the high school athletes continue to perform significantly worse than control subjects for up to seven days following the injury (F = 2.90; P <.005).(12) This age-based disparity in performance on neuropsychological testing is not correlated with self-report of postconcussion symptoms.(12) “Of note is the fact that high school athletes appear to recover more poorly as compared to collegiate athletes, despite the latter typically incurring more acutely severe injuries as a result of being bigger, faster, and stronger. There are several possible explanations for this disparity between high school and collegiate football players: the brain may not yet be fully developed, resulting in a lower injury threshold; the blood vessels may tear more easily in the less developed brain; the skull is thinner, which could provide less protection to the brain; there may be fewer medical staff members available at high school games; and/or poor body control and technique might make younger players more susceptible to brain injury following a poorly executed tackle.(24) In fact, one explanation may be that for various reasons, including having weaker necks, high school football players were found to sustain more absolute force to brain per hit while playing football that college athletes.(25) However, football players who have a history of previous concussions are at a greatly increased risk of experiencing future concussions as compared to athletes without a history of such impacts.(26) “Basketball: One of the most popular sports across both genders, basketball was played by approximately 13.8 million men in high school, along with 11 million women in high school, between the fall of 1982 and the spring of 2008.(3) An additional 375,000 men and 328,00 women competed in college.(3) Injuries. “In a survey of high school athletic trainers evaluating athletes over the 1995–97 seasons, men experienced a rate of 0.75 concussions per 100 player-seasons. This was slightly less than the rate of 1.04 concussions per 100 player-seasons experienced by women.(21) In college athletes, a 15-year analysis of the NCAA ISS found that men had a rate of 0.16 concussions per 1000 A-E (95% CI = 0.14, 0.17) as compared to a rate of 0.22 concussions per 1000 A-E in women (95% CI = 0.20, 0.24).(18) An analysis over the 2005–06 season in high school showed a similar relationship between male and female basketball players, with men experiencing a lower concussion rate than women (0.07 and 0.21 concussions per 1000 A-Es respectively, RR = 2.93, 95% CI = 1.64, 5.24, P < .01). This difference was largely accounted for by concussions during competition. Whereas men and women both had a rate of 0.06 concussions per 1000 A-E in practice, women had a rate of 0.60 concussions per 1000 A-E in games as compared to 0.11 in men. In college basketball, men experienced fewer concussions in both practices (0.22 versus 0.31 concussions per 1000 A-E) and games (0.45 versus 0.85 concussions per 1000 A-E).(23) “Concussions represented a greater proportion of the total injuries experienced by women as compared to men (11.7% and 3.8% respectively, Injury PR = 3.09, 95% CI = 2.98, 3.20, P < .01).(23) In men's high school basketball, concussions accounted for 4.1% of all the injuries sustained during practices and 5.0% of those sustained during games; this difference was not significant.(27), Women, however, experienced 3.4 times the risk of suffering a concussion during a game versus practice, with concussions accounting for 4.7% of all injuries during practice and 8.5% during games.(27) This relationship between practice and games was confirmed in another study, indicating that women have a significant increase in risk at games (Injury PR = 5.82, 95% CI = 2.06, 16.49), but men had no significant difference.(28) “While playing basketball, concussions are associated with different activities in men than in women. Women receive a greater proportion of their concussions while ball handling/dribbling (19.0% versus 10.4%, Injury PR = 1.83, 95% CI = 1.65, 2.02, P = .01) and while defending (22.2% versus 13.4%, Injury PR = 1.66, 95% CI = 1.52, 1.81, P < .01). Men, on the other hand, experience a greater proportion of their concussions chasing loose balls (26.0% versus 10.6%, Injury PR = 2.46, 95% CI = 2.28, 2.64, P < .01) and rebounding (30.5% versus 16.6%, Injury PR = 1.83, 95% CI = 1.72, 1.95, P < .01). A higher proportion of men than women experienced a concussion due to collision with the playing surface (34.0% and 22.0% respectively, Injury PR = 1.54, 95% CI = 1.46, 1.63, P < .01). Some women, but no men, reported a concussion due to contact with the ball (6.0%).(23) “Male and female basketball players also have differing rates of symptom resolution and return to play. Two days post-concussion, significantly more men returned to play than women (39% and 15% respectively, Injury PR = 38.21, 95% CI = 30.44, 47.96, P < .01).(23) “Soccer: In the US, soccer is growing in popularity. Between 1982 and 2008, approximately 7.2 million men and 5.2 million women played soccer at the high school level. An additional 430,000 men and 322,000 women competed in college.(3) “Injuries In a study of athletic trainers from 1995 to 1997, the rate of concussions in male soccer players was found to be 0.92 injuries per 100 player-seasons.(21) According to data reported to the NCAA ISS, men in college had a rate of 0.28 concussions per 1000 A-E (95% CI = 0.25, 0.30) over the time period from the 1988–89 season through 2003–04 season.(18) One study examining the 2005–06 season found that high school men experienced a rate of 0.04 concussions per 1000 A-E in practice and 0.59 concussions per 1000 A-E in games (0.22 concussions per 1000 A-E overall). It was reported that college soccer players experienced 0.24 concussions per 1000 A-E in practice and 1.38 concussions per 1000 A-E in games (0.49 concussions per 1000 A-E overall).(23) Significantly more concussions occurred in games than in practice (Injury PR = 6.94, 95% CI = 2.01, 23.95).(28) “Concussions in male soccer players typically occur as a result of head to head collisions in the act of heading the ball (40.5%). As expected, concussions were responsible for 64.1% of injuries that occurred while heading the ball. Another common cause of concussions in soccer players was contact with another person (85.3%). Goalies were significantly more likely to experience a concussion, as 21.7% of all injuries to goalkeepers were concussions as compared with 11.1% of all injuries to other players (Injury PR = 1.96, 95% CI = 1.92, 2.00, P < .01).(23) “In the aforementioned study of athletic trainers from 1995 to 1997, the rate of concussions in women was 1.14 injuries per 100 player-seasons.(21) According to data from the NCAA ISS, women in college had a rate of 0.41 concussions per 1000 A-E (95% CI = 0.38, 0.44) from the 1988–89 season through the 2003–04 season.(18) In the aforementioned study of the 2005–06 season, high school women were shown to have a rate of 0.09 concussions per 1000 A-E in practice and 0.97 concussions per 1000 A-E in games (0.36 concussions per 1000 A-E overall). In college, female soccer players experienced 0.25 concussions per 1000 A-E in practice and 2.80 concussions per 1000 A-E in games (0.63 concussions per 1000 A-E overall).(23) Concussions accounted for 11.4% of the injuries experienced by women during games and 2.4% of all the injuries experienced during practice.(27) Like men, women were significantly more likely to experience concussions in games as opposed to practice (Injury PR = 16.7, p < 0.01).(28) “As with men, concussions in female soccer players typically occur as a result of head to head collisions while heading the ball (36.7%). Women experienced fewer concussions as a result of contact with another person (58.3%, Injury PR = 1.46, 95% CI = 1.45, 1.48, P < .01). On the other hand, women experienced more concussions than men as a result of contact with the ground (22.6% and 6.0% respectively, Injury PR = 3.77, 95% CI = 3.56, 4.00, P < .01) and contact with the soccer ball (18.3% and 8.2% respectively, Injury PR = 3.68, 95% CI = 3.45, 3.92, P < .01).(23) “There appear to be differences in the rate of recovery from concussion between high school and collegiate athletes. College athletes, despite experiencing a higher rate of loss of consciousness, recovered by the third day post-concussion. Interestingly, an athlete's self-report of post-concussion symptoms may not be associated with return to baseline performance on neuropsychologic testing, as most high school athletes reported recovery by the fifth day post-concussion, but experienced neuropsychological deficits seven days following injury.(12) Discussion “The rate of concussion has been increasing steadily over the past two decades. This trend is likely due to improvement in the detection of concussion, but may also reflect an increase in the true number of concussive impacts occurring. As athletes get bigger, stronger, and faster, it is logical that the forces associated with their collisions would also increase in magnitude. It is important to realize that there is currently no effective headgear that prevents concussions so, as the number of forceful collisions increase, the number of concussions would be expected to increase. “In general, athletes tend to have a higher risk of concussion in competition as compared to practice. However, given the higher frequency of practices compared to games, and the resulting total number of concussions occurring in practice, one way to quickly and drastically reduce a sport's concussion risk would be to limit unnecessary contact in practice. The majority of concussions in high school athletes resulted from participation in football, followed by girls' soccer, boys' soccer, and girls' basketball. “Within a given sport, “In general, there are simple things that can be done to reduce the incidence of concussion in sports. Pre-participation examinations should be mandatory. If a physician or coach has questions about an athlete's readiness to compete, the athlete's safety should not be risked. At this session, or at a stand-alone meeting, concussion education should be afforded all athletes, especially for those competing in a collision or contact sport. Proper strength and conditioning, especially focused on strengthening the muscles of the neck, is a suitable way to limit the forces experienced by the head. Properly trained coaches, athletic trainers, and medical staff are on the front line in concussion education, diagnosis, and management, and are key to reducing the incidence and severity of concussions. Finally, quality officiating can help to identify potentially dangerous situations and ensure the activity does not result in injury. Conclusion “Concussions and head injuries may never be completely eliminated from sports. However, with better data comes an improved understanding of the types of actions and activities that typically result in concussions. With this knowledge can come improved techniques and rule changes to minimize the rate and severity of concussions in sports. This paper identifies the factors that affect concussion rate. [Clin Sports Med. 2011 January; 30(1): 1–17. The Epidemiology of Sport-Related Concussion Daniel H. Daneshvar, MA, MD / PhD Graduate Student,a Christopher J. Nowinski, Co-Director, Co-Founder,b,h Ann McKee, Co-Director, Associate Professor of Neurology and Pathology,b,i and Robert C. Cantu, MD, Co-Director, Clinical Professor, Chief of Neurosurgery Service, Chairman, Director of Sports Medicine, Co-Director, Co-Founder]

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