Does amateur boxing lead to chronic brain damage? A review of some recent investigations

Incidence Rates and Pathology Types of Boxing-Specific Injuries: A Systematic Review and Meta-analysis of Epidemiology Studies in the 21st Century

Background

To the best of our knowledge, an evidence-based investigation into 21st-century boxing-specific injury rates and types has yet to be performed.

Purpose

To provide an overview and quantitative synthesis of the incidence rates (IRs) and pathological categorizations of boxing-specific injuries in the 21st century.

Study Design

Systematic review; Level of evidence, 3.

Methods

Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched literature published from January 2000 to November 2021 in PubMed and the Cochrane Library systematically for qualifying epidemiology studies of organized boxing activities across the world. Two independent reviewers completed the literature review, data extraction, and quality assessment. The IRs of injuries per 1000 boxers (IR_N), per 1000 competition exposures (IR_E), and per 1000 minutes of competition (IR_C) or training (IR_T) were subsequently calculated. Single-arm meta-analyses were performed for the subgroups of different types of boxing. Sample size weighted means were calculated using a random-effects model in all studies with 95% CIs.

Results

Out of an initial 9584 articles, 14 studies were included, with most (11/14) having a moderate level of quality. The pooled IR_N in overall injuries was 223.9 (95% CI, 157.5-290.4), the IR_E was 233.3 (95% CI, 161.3-305.2), and the IR_C was 13.0 (95% CI, 8.9-17.1). In professional boxing, the IR_N (399.8), IR_E (379.8), and IR_C (23.9) were all significantly higher than in the amateur and female groups. The IR_E (76.6 vs 250.6; P < .000) and IR_C (9.2 vs 15.4; P < .000) in amateur boxing were significantly lower in studies between 2010 and 2019 than in earlier studies. For pathology categorization, the pooled frequencies were 12.3% (95% CI, 8.7%-15.9%) for concussion, 21.4% (95% CI, 14.1%-28.6%) for skin laceration, 30.2% (95% CI, 22.1%-38.2%) for soft tissue contusion, 15.3% (95% CI, 7.7%-22.9%) for sprain and muscle/ligament injury, and 11.4% (95% CI, 2.7%-20.1%) for fracture.

Conclusion

IRs of injury remain high in professional boxing, although they have decreased in the past 10 years in amateur boxing. Soft tissue contusion was the most common injury type. Better exposure measurements and epidemiologic indicators should be applied in future studies.

Registration

CRD42021289993 (PROSPERO).

Amateur Boxing and Dementia: Cognitive Impairment Within the 35-Year Caerphilly Cohort Study

OBJECTIVE

To examine the long-term effects of amateur boxing in a representative population sample of men.

DESIGN

The sample was examined every 5 years for 35 years. Cognition was assessed repeatedly from the third examination. Previous boxing experience and dementia were assessed at the fifth examination, and dementia assessed subsequently through medical records.

SETTING AND ASSESSMENT OF RICK FACTORS

The Caerphilly Prospective Study investigates risk factors for a range of chronic diseases of diseases. These include life style and behavior, together with biological factors relevant to vascular disease.

PARTICIPANTS

1123 adult men aged 45 to 59 years at baseline, followed for 35 years.

MAIN OUTCOME MEASURES

Cognitive impairment.

RESULTS

A report by a subject of having boxed "seriously" when younger was associated with a 2-fold increase in cognitive impairment [odds ratio (OR) = 2.27; 95% confidence intervals = 1.18-4.38]. For amnestic (Alzheimer-like) impairment, this rises to OR = 2.78 (95% confidence limits 1.37-5.65). Having boxed is associated with an "advancement" in the onset of the dementia (4.8 years; 95% confidence limits 0.9-8.8 years).

CONCLUSIONS

Amateur boxing is associated with an increased risk and an earlier onset of cognitive impairment and dementia.

Concussions, cuts and cracked bones: A systematic literature review on protective headgear and head injury prevention in Olympic boxing

In 2013, the International Boxing Association (AIBA) prohibited the use of headguards for elite male Olympic boxing competitions. Could the removal of the headguard from elite male boxing competitions potentially cause increased injury risk for boxers? The aim of the literature review is to analyse current knowledge about the use of protective headgear and injury prevention in boxing, in order to determine if there are increased injury risks associated with headguard use. Peer-reviewed studies (language: English, Norwegian, Swedish, Danish and Dutch) published from 1980 and onwards were considered. Five academic databases and grey literature sources were searched, and articles were assessed for methodological quality. Only studies that included boxers as the study population with headguards as a factor were considered. A total of 39 articles were included in the review. The analysis of the reviewed literature indicates that headguards protect well against lacerations and skull fractures, while less is known about the protective effects against concussion and other traumatic brain injuries. Most of the analysed studies however use indirect evidence, obtained through self-report or observational techniques with relatively small non-representative samples. There are almost no randomised control trials, longitudinal research designs or samples from recreational boxing. Therefore, AIBA's decision to remove the headguard has to be seen with caution and injury rates among (male) boxers should be continuously evaluated.

Predictive Power of Head Impact Intensity Measures for Recognition Memory Performance

Subconcussive head injuries are connected to both short-term cognitive changes and long-term neurodegeneration. Further study is required to understand what types of subconcussive impacts might prove detrimental to cognition. We studied cadets at the US Air Force Academy engaged in boxing and physical development, measuring head impact motions during exercise with accelerometers. These head impact measures were compared with post-exercise memory performance. Investigators explored multiple techniques for characterizing the magnitude of head impacts. Boxers received more head impacts and achieved lower performance in post-exercise memory than non-boxers. For several measures of impact motion, impact intensity appeared to set an upper bound on post-exercise memory performance - stronger impacts led to lower expected memory performance. This trend was most significant when impact intensity was measured through a novel technique, applying principal component analysis to boxer motion. Principal component analysis measures also captured more distinct impact information than seven traditional impact measures also tested.

Structural imaging of mild traumatic brain injury may not be enough: overview of functional and metabolic imaging of mild traumatic brain injury

A majority of patients with traumatic brain injury (TBI) present as mild injury with no findings on conventional clinical imaging methods. Due to this difficulty of imaging assessment on mild TBI patients, there has been much emphasis on the development of diffusion imaging modalities such as diffusion tensor imaging (DTI). However, basic science research in TBI shows that many of the functional and metabolic abnormalities in TBI may be present even in the absence of structural damage. Moreover, structural damage may be present at a microscopic and molecular level that is not detectable by structural imaging modality. The use of functional and metabolic imaging modalities can provide information on pathological changes in mild TBI patients that may not be detected by structural imaging. Although there are various differences in protocols of positron emission tomography (PET), single photon emission computed tomography (SPECT), functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and magnetoencephalography (MEG) methods, these may be important modalities to be used in conjunction with structural imaging in the future in order to detect and understand the pathophysiology of mild TBI. In this review, studies of mild TBI patients using these modalities that detect functional and metabolic state of the brain are discussed. Each modality's advantages and disadvantages are compared, and potential future applications of using combined modalities are explored.

Neuropsychological, Metabolic, and GABAA Receptor Studies in Subjects with Repetitive Traumatic Brain Injury

Repetitive traumatic brain injury (rTBI) occurs as a result of mild and accumulative brain damage. A prototype of rTBI is chronic traumatic encephalopathy (CTE), which is a degenerative disease that occurs in patients with histories of multiple concussions or head injuries. Boxers have been the most commonly studied patient group because they may experience thousands of subconcussive hits over the course of a career. This study examined the consequences of rTBI with structural brain imaging and biomolecular imaging and investigated whether the neuropsychological features of rTBI were related to the findings of the imaging studies. Five retired professional boxers (mean age, 46.8 ± 3.19 years) and four age-matched controls (mean age, 48.5 ± 3.32 years) were studied. Cognitive-motor related functional impairment was assessed, and all subjects underwent neuropsychological evaluation and behavioral tasks, as well as structural brain imaging and functional-molecular imaging. In neuropsychological tests, boxers showed deficits in delayed retrieval of visuospatial memory and motor coordination, which had a meaningful relationship with biomolecular imaging results indicative of neuronal injury. Morphometric abnormalities were not found in professional boxers by structural magnetic resonance imaging (MRI). Glucose metabolism was impaired in frontal areas associated with cognitive dysfunction, similar to findings in Alzheimer's disease. Low binding potential (BP) of (18)F-flumazenil (FMZ) was found in the angular gyrus and temporal cortical regions, revealing neuronal deficits. These results suggested that cognitive impairment and motor dysfunction reflect chronic damage to neurons in professional boxers with rTBI.

The long-term effects of repetitive mild head injuries in sports

At least 300 000 sports-related concussions occur in the United States annually. With millions of American athletes, the long-term effects of repeated concussion or mild traumatic brain injury are an important topic. Unfortunately, there is a lack of strong data on the causality or prevalence of long-term effects among athletes. Chronic traumatic encephalopathy (CTE), a progressive neurodegenerative tauopathy, with associated clinical, behavioral, and neuropathological findings, is an important clinical entity in need of further study. Diffusion tensor imaging can elucidate trauma-induced white matter damage, but the diagnosis of CTE cannot be proven until postmortem neuropathology shows characteristic neurofibrillary and astrocytic tangles. Concern exists that athletes subject to repeated concussive and even subconcussive blows may be at risk of CTE, but no definitive data exist due to the difficulty in diagnosis. Animal models suggest that mild traumatic brain injuries lead to primarily a metabolic derangement with increased excitotoxic neurotransmitter release, extracellular potassium, and intracellular calcium. Further understanding of the underlying pathophysiology may eventually lead to better therapeutic and diagnostic options for the treating clinician.

Movement disorders secondary to craniocerebral trauma

Over the past few decades it has been recognized that traumatic brain injury may result in various movement disorders. In survivors of severe head injury, post-traumatic movement disorders were reported in about 20%, and they persisted in about 10% of patients. The most frequent persisting movement disorder in this population is kinetic cerebellar outflow tremor in about 9%, followed by dystonia in about 4%. While tremor is associated most frequently with cerebellar or mesencephalic lesions, patients with dystonia frequently have basal ganglia or thalamic lesions. Moderate or mild traumatic brain injury only rarely causes persistent post-traumatic movement disorders. It appears that the frequency of post-traumatic movement disorders overall has been declining which most likely is secondary to improved treatment of brain injury. In patients with disabling post-traumatic movement disorders which are refractory to medical treatment, stereotactic neurosurgery can provide long-lasting benefit. While in the past the primary option for severe kinetic tremor was thalamotomy and for dystonia thalamotomy or pallidotomy, today deep brain stimulation has become the preferred treatment. Parkinsonism is a rare consequence of single head injury, but repeated head injury such as seen in boxing can result in chronic encephalopathy with parkinsonian features. While there is still controversy whether or not head injury is a risk factor for the development of Parkinson's disease, recent studies indicate that genetic susceptibility might be relevant.

Chronic traumatic encephalopathy: a critical appraisal

Chronic traumatic encephalopathy (CTE) formerly known as dementia pugilistica is a long-term neurodegenerative disorder associated with repeated subconcussive head injuries in high-contact sports. We reviewed the existing literature on CTE and examined epidemiological trends, risk factors, and its temporal progression, and proposed the underlying pathophysiological mechanisms that may provide unique insights to clinicians with an in-depth understanding of the disease to aid in the diagnosis and prevention, and provide future perspectives for research via search of Medline and Cochrane databases as well as manual review of bibliographies from selected articles and monographs. The prevalence of CTE in recent years is on the rise and almost exclusively affects men, with pathologic signs characterized by progressive memory loss, behavioral changes, and violent tendencies with some patients demonstrating Parkinsonian-like symptoms and signs. Many patients with CTE die following suicide, accident, or complications of drug or alcohol use. Postmortem pathologic analysis is characterized by neurofibrillary tangles and Aβ plaques in 50 % of cases. Currently, there are no ante-mortem diagnostic criteria, but modern imaging techniques such as functional magnetic resonance (MR) imaging, MR spectroscopy, and diffusion tension imaging hold promise for delineating the future diagnostic criteria. Further long-term longitudinal studies are warranted to investigate risk factors that will enhance understanding of the disease progression and its pathogenesis.

Evidence of cognitive dysfunction after soccer playing with ball heading using a novel tablet-based approach

Does frequent head-to-ball contact cause cognitive dysfunctions and brain injury to soccer players? An iPad-based experiment was designed to examine the impact of ball-heading among high school female soccer players. We examined both direct, stimulus-driven, or reflexive point responses (Pro-Point) as well as indirect, goal-driven, or voluntary point responses (Anti-Point), thought to require cognitive functions in the frontal lobe. The results show that soccer players were significantly slower than controls in the Anti-Point task but displayed no difference in Pro-Point latencies, indicating a disruption specific to voluntary responses. These findings suggest that even subconcussive blows in soccer can result in cognitive function changes that are consistent with mild traumatic brain injury of the frontal lobes. There is great clinical and practical potential of a tablet-based application for quick detection and monitoring of cognitive dysfunction.

Chronic traumatic encephalopathy: the dangers of getting "dinged"

Chronic traumatic encephalopathy (CTE) is a form of neurodegeneration that results from repetitive brain trauma. Not surprisingly, CTE has been linked to participation in contact sports such as boxing, hockey and American football. In American football getting "dinged" equates to moments of dizziness, confusion, or grogginess that can follow a blow to the head. There are approximately 100,000 to 300,000 concussive episodes occurring in the game of American football alone each year. It is believed that repetitive brain trauma, with or possibly without symptomatic concussion, sets off a cascade of events that result in neurodegenerative changes highlighted by accumulations of hyperphosphorylated tau and neuronal TAR DNA-binding protein-43 (TDP-43). Symptoms of CTE may begin years or decades later and include a progressive decline of memory, as well as depression, poor impulse control, suicidal behavior, and, eventually, dementia similar to Alzheimer's disease. In some individuals, CTE is also associated with motor neuron disease similar to amyotrophic lateral sclerosis. Given the millions of athletes participating in contact sports that involve repetitive brain trauma, CTE represents an important public health issue. In this review, we discuss recent advances in understanding the etiology of CTE. It is now known that those instances of mild concussion or "dings" that we may have previously not noticed could very well be causing progressive neurodegenerative damage to a player's brain. In the future, focused and intensive study of the risk factors could potentially uncover methods to prevent and treat this disease.

Concussions in soccer: a current understanding

OBJECTIVE

Traumatic brain injury (TBI) is a significant public health problem in the United States, with approximately 1.5-2 million TBIs occurring each year. However, it is believed that these figures underestimate the true toll of TBI. Soccer is the most popular sport in the world and has a following of millions in the United States. Soccer is a sport not traditionally identified as high-risk for concussions, yet several studies have shown that concussion rates in soccer are comparable to, and often exceed those of, other contact sports. As many as 22% of all soccer injuries are concussions.

METHODS

Soccer is a sport not traditionally identified as high risk for concussions, yet several studies have shown that concussion rates in soccer are comparable to, and often exceed those of, other contact sports. As many as 22% of all soccer injuries are concussions. Head injury during soccer is usually the result of either "direct contact" or contact with the ball while "heading" the ball. Relationships between the number of headers sustained in a single season and the degree of cognitive impairment (attention and visual/verbal memory) have been demonstrated. It is also likely that multiple concussions may cause cumulative neuropsychologic impairment in soccer players.

RESULTS

Although our understanding of risk factors for sports-related concussions is far from complete, there is great potential for prevention in sports-related concussions. Several measures must be taken to avert the development of concussions in soccer and, when they take place, reduce their effects. These include the development and testing of effective equipment during play, the maintenance of regulatory standards for all such equipment, educating young athletes on the safe and appropriate techniques used during play, and strict adherence to the rules of competition.

CONCLUSIONS

In spite of such preventive measures, concussions in soccer will continue to occur. Considering the frequency of concussions in soccer, the serious sequelae of these concussions, and because almost half of concussed soccer players were noncompliant with recommended American Academy of Neurology return-to-play guidelines, further measures must be taken to protect players, in addition to understanding those criteria that result in removing an injured player from competition and the steps by which to safely return an athlete to competition after injury.

Policy statement—Boxing participation by children and adolescents

Thousands of boys and girls younger than 19 years participate in boxing in North America. Although boxing provides benefits for participants, including exercise, self-discipline, and self-confidence, the sport of boxing encourages and rewards deliberate blows to the head and face. Participants in boxing are at risk of head, face, and neck injuries, including chronic and even fatal neurologic injuries. Concussions are one of the most common injuries that occur with boxing. Because of the risk of head and facial injuries, the American Academy of Pediatrics and the Canadian Paediatric Society oppose boxing as a sport for children and adolescents. These organizations recommend that physicians vigorously oppose boxing in youth and encourage patients to participate in alternative sports in which intentional head blows are not central to the sport.

Sports concussion and the risk of chronic neurological impairment

Intense recent media focus on long-term outcomes from sports concussion has highlighted concerns on both cognitive deterioration and mental health issues, such as depression and suicide. At this time, the scientific evidence to support these views is limited, with only a handful of cases thus far reported. Based on the literature on this topic that extends back over 50 years, it is clear that only a small percentage of athletes suffer such sequelae presumably due to recurrent concussive or subconcussive head impacts. At this stage, determining which athletes are at future risk is not possible; however, following existing concussion guidelines (eg, Zurich guidelines) is likely to be the safest option based on current evidence.

Playing soccer increases serum concentrations of the biochemical markers of brain damage S-100B and neuron-specific enolase in elite players: a pilot study

PRIMARY OBJECTIVE

To analyse serum concentrations of two biochemical markers of brain tissue damage, S-100B and NSE (neurone-specific enolase), in male soccer players in connection to the game.

METHODS

Blood samples were taken in players before and after a competitive game and the numbers of headers and of trauma events during soccer play were assessed.

RESULTS

Both S-100B and NSE were significantly raised in serum samples obtained after the game in comparison with the pre-game values (S-100B: 0.118 +/- 0.040 microg L(-1) vs 0.066 +/- 0.025 microg L(-1), p < 0.001; NSE: 10.29 +/- 2.16 microg L(-1) vs 8.57 +/- 2.31 microg L(-1), p < 0.001). Only changes in S-100B concentrations (post-game minus pre-game values) were statistically significantly correlated to the number of headers (r = 0.428, p = 0.02) and to the number of other trauma events (r = 0.453, p = 0.02).

CONCLUSION

Playing competitive elite soccer was found to cause increase in serum concentrations of S-100B and NSE. Increases in S-100B were significantly correlated to the number of headers, and heading may accordingly have contributed to these increases.

Neurologic injuries in boxing and other combat sports

Many sports have neurologic injury from incidental head contact; however, combat sports allow head contact, and a potential exists for acute and chronic neurologic injuries. Although each combat sport differs in which regions of the body can be used for contact, they are similar in competitor exposure time. Their acute injury rates are similar; thus their injuries can appropriately be considered together. Injuries of all types occur in combat sports, with injuries in between one fifth to one half of all fights in boxing, karate, and tae kwon do. Most boxing injuries are to the head and neck region. In other combat sports, the head and neck region are the second (after the lower limbs) or the first most common injury site.

Comparison of baseline neuropsychological testing in amateur versus professional boxers

The aim of the study is to investigate cognitive functions in boxers. The study population was composed of 2 groups of male boxers with no history of head concussions (except during boxing): a) 33 amateurs at their first examination; b) 27 professionals. Subjects were requested to: a) fulfill a questionnaire collecting demographic data, level of education, occupational status, boxing record (for professionals), and number of head concussions during boxing; b) undergo a computerized neuropsychological (NP) test (CogSport) measuring simple and complex reaction time (RT). Professionals were significantly (P < 0.0001) older (29.4 +/- 4.19 years) and started boxing at a younger age (14.5 +/- 3.94 vs 20.3 +/- 4.77 years, P < 0.0001) than debutants (24.1 +/- 5.13 years). Debutants showed significantly shorter simple RTs than professionals, both at the beginning (0.244 +/- 0.007 vs 0.249 +/- 0.007 s, P = 0.005) and the end (0.247 +/- 0.007 vs 0.251 +/- 0.008 s, P = 0.028) of NP test. Complex RTs did not differ between groups. Professionals showed a positive significant correlation between simple RT at the beginning of NP test and the total number of disputed (P = 0.043) and won (P = 0.035) bouts. In conclusion, professionals show a longer simple RT compared with debutants, with no difference regarding more complex cognitive tasks. A possible explanation may be found in an adaptation of skilled boxers to better (and longer) evaluate external stimuli before giving a motor response.

KEYWORDS

boxing; CogSport; reaction time; neuropsychological test.

Do UK university football club players suffer neuropsychological impairment as a consequence of their football (soccer) play?

Male players from football and rugby clubs and sportsmen from a variety of noncontact sports clubs at a UK university were compared on biographical and neuropsychological test measures. A data analysis paradigm was developed and employed to control the inflation of Type 1 error rate due to multiple hypotheses testing. Rugby players sustained most head injuries in their chosen sport, but neuropsychological tests of attention, memory, and executive function provided no evidence of performance impairment attributable to the number of head injuries sustained or the football, rugby, or noncontact sport groups. Footballers' heading frequency was related to the number of football head injuries sustained, but no relationship was detected between footballers' heading frequency and their neuropsychological test performance. Following discussion of pertinent methodological limitations it is concluded that there was no evidence in this dataset of neuropsychological impairment consistent with either mild head injury incidence or football heading frequency. However, a need for further research examining the long-term neuropsychological consequences of such head injuries was identified.

Repeatedly Heading a Soccer Ball Does Not Increase Serum Levels of S-100B, a Biochemical Marker of Brain Tissue Damage: an Experimental Study

OBJECTIVES: The aim of the study was to analyse whether the controlled heading of soccer balls elicits increased serum concentrations of a biochemical marker of brain tissue damage S-100B. METHODS: Nineteen male soccer players were randomly divided into two groups, A and B. Group A headed a soccer ball falling from 18 m five times, while group B served as controls (no heading). Blood samples were taken before and 0.5 h, 2 h and 4 h after the heading for analysis of S-100B. RESULTS: No statistically significant (p > 0.05) increases in serum concentrations of S-100B were encountered in group A at 0.5 h (0.109 +/-0.024 mug/L), 2 h (0.098 +/- 0.026 mug/L), and 4 h (0.113 +/- 0.035 mug/L) when the blood samples obtained before and after the heading were compared (0.157 +/- 0.134 mug/L). No statistically significant difference was found when the serum concentrations of S-100B were compared between groups A and B either before or after heading. CONCLUSIONS: Heading a soccer ball dropped from a height of 18 m five times was not found to cause an increase in serum concentrations of S-100B, indicating that the impact was not sufficient to cause biochemically discernible damage of brain tissue.

The Evidence for Chronic Traumatic Encephalopathy in Boxing

The sport of boxing has been the source of much debate, with concerns about the neurological risks of participating having led to many calls to ban the sport. This review seeks to establish an evidence base for the development of boxing-related chronic traumatic encephalopathy (CTE) and to determine the relevance of this information to the modern day sport.The clinical features of CTE include various symptoms affecting the pyramidal and extrapyramidal systems, which manifest most often as disturbed gait and coordination, slurred speech and tremors, as well as cerebral dysfunction causing cognitive impairments and neurobehavioural disturbances. Both amateur and professional boxers are potentially at risk of developing CTE. No current epidemiological evidence exists to determine the prevalence of this condition in modern day boxing, despite 17% of professional boxers in Britain with careers in the 1930-50s having clinical evidence of CTE. As medical presence within the sport increases and with modern boxers likely to have shorter careers, a reduced exposure to repetitive head trauma, and improved treatment and understanding of the development of CTE will occur. This should lead to the incidence of CTE diminishing in boxing populations.

Serum concentrations of two biochemical markers of brain tissue damage S-100B and neurone specific enolase are increased in elite female soccer players after a competitive game

BACKGROUND

It is a matter of debate whether or not ordinary heading of the ball in soccer causes injury to brain tissue.

OBJECTIVE

To analyse concentrations of the biochemical markers of brain tissue damage S-100B and neurone specific enolase (NSE) in serum of female elite soccer players in association with a competitive game.

METHODS

Venous blood samples were obtained from 44 female soccer players before and after a competitive game for analysis. The number of headers and trauma events (falls, collisions, etc) was assessed from videotape recordings for each player.

RESULTS

Concentrations of both brain damage markers were increased after the game (S-100B, 0.18 (0.11) v 0.11 (0.05) microg/l (p = 0.000); NSE, 10.14 (1.74) v 9.05 (1.59) microg/l (p = 0.001)). There was a significant correlation between changes in S-100B concentrations and both the number of headers (r = 0.430, p = 0.004) and the number of other trauma events (r = 0.517, p < 0.001).

CONCLUSION

The concentrations of both S-100B and NSE were increased by game associated activities and events. The increases in S-100B concentration were significantly related to the number of headers and other trauma events, which indicates that both these factors may have contributed to these increases.

Mild head injury in sports

Mild head injury has been recognized as producing numerous "postconcussive" symptoms that temporarily reduce an individual's ability to function. Controversy exists over the short-and long-term effects of mild head injuries, and the effects of repeated concussive blows to the head have not been sufficiently studied. Amateur and professional athletes provide an excellent population for the examination of many aspects of postconcussive syndrome. The nature, incidence, and cognitive and emotional symptoms of mild head injury, are reviewed within, the framework of professional and amateur sports. Particular attention is paid to the few available prospective studies of amateur boxers and collegiate football players.

The risk of chronic traumatic brain injury in professional boxing: change in exposure variables over the past century

OBJECTIVES

To determine if boxing exposure has changed over time and hence if current professional boxers are at the same risk of developing chronic traumatic brain injury (CTBI) as historical controls.

DESIGN

Literature review of published studies and analysis of data of active professional boxers.

SUBJECTS

Professional boxers in the United Kingdom and Australia.

MAIN OUTCOME MEASURES

Boxing history and participation in sparring and professional bouts.

RESULTS

Since the 1930s, the average duration of a professional boxer's career has dropped from 19 years to five years, and the mean number of career bouts has reduced from 336 to 13. This is despite no significant decline in participation rates from 1931 until 2002.

CONCLUSIONS

The incidence of boxing related CTBI will diminish in the current era of professional boxing because of the reduction in exposure to repetitive head trauma and increasing medical monitoring of boxers, with preparticipation medical and neuroimaging assessments resulting in the detection of early and potentially pre-symptomatic cases of CTBI.

Head injuries in youth soccer players presenting to the emergency department

BACKGROUND

There has been recent concern about neuropsychological injuries experienced by soccer players, particularly related to the purposeful heading of the ball. There are few population based analyses examining whether this is a legitimate concern.

OBJECTIVES

To explore, using an existing injury surveillance system, one of many parts of this issue: acute injuries requiring emergency medical care experienced by youth soccer players.

METHODS

Descriptive epidemiological analysis of emergency department injury surveillance data (1996-2001) for youths aged 10-24 years from the Kingston sites of the Canadian Hospital Injury Reporting and Prevention Program.

RESULTS

A total of 1714 cases of soccer injury were identified (mean 286 a year); 235 (13.7%) involved diagnoses of injuries to the head. Leading mechanical factors resulting in head injury were contact with other players or persons (153/235; 65.1%) and balls (62/235; 26.4%). Heading was reported in 4/62 (6%) of the ball contact injuries, and attempted heading was reported in 15/153 (9.8%) of the cases involving person to person contact. Unspecified head to head contact between players was reported in 39 cases.

CONCLUSIONS

Minor head injuries that result in emergency medical treatment do not happen often in youth soccer, and very few can be attributed to the purposeful heading of the ball. Player contact injuries appear to be a more important injury control concern. This study informs one of many aspects of the soccer heading injury debate.

A prospective controlled study of cognitive function during an amateur boxing tournament

BACKGROUND

Few studies have reported acute postbout cognitive function in amateur boxers, and none have documented the effects of repeated boxing bouts within a short time frame.

OBJECTIVE

To determine whether participation in a 7-day amateur boxing tournament is associated with acute deterioration in cognitive test performance.

METHODS

A prospective study was done of 82 collegiate amateur boxers participating in a 7-day single elimination tournament and a group of 30 matched nonboxing control participants. No participants had a history of recent concussion or past history of brain injury. For boxers, cognitive assessment using a computerized test battery was performed before the tournament and within 2 hours of completing each bout. Tests of simple and choice reaction time, working memory, and learning were administered. Analysis of variance was conducted to compare the serial performance of control participants with that of boxers participating in one, two, and three bouts.

RESULTS

The 82 boxers fought 159 times. Cognitive testing was performed after 142 of these bouts. On simple reaction time, choice reaction time, and working memory tasks, the serial performance of boxers participating in three bouts (n = 22) was equivalent to that of boxers participating in two bouts (n = 22) and one bout (n = 32) and to nonboxing control participants (n = 30). An improvement in performance was observed on the learning task in boxers participating in three bouts. Boxers whose bout was stopped by the referee (n = 7) displayed significant slowing in simple and choice reaction time.

CONCLUSIONS

With the exception of boxers whose contest is stopped by the referee, amateur boxers participating in multiple bouts during a 7-day tournament display no evidence of cognitive dysfunction in the immediate postbout period.

The neuropsychology of heading and head trauma in Association Football (soccer): a review

Association Football (soccer) is the most popular and widespread sport in the world. A significant proportion of the injuries suffered in football are head injuries involving trauma to the brain. In normal play, head trauma frequently arises from collisions, but some researchers have claimed that it also may arise as a consequence of heading the ball. Although assessments based on biomechanical analyses are equivocal on the potential for brain injury due to football heading, a growing literature seems to support the claim that neuropsychological impairment results from general football play and football heading in particular. However, this review suggests a distinction is required between the neuropsychological effects of concussive and subconcussive head trauma and that all of the neuropsychological studies conducted so far suffer from methodological problems. At best, a few of these studies may be regarded as exploratory. The review concludes that presently, although there is exploratory evidence of subclinical neuropsychological impairment as a consequence of football-related concussions, there is no reliable and certainly no definitive evidence that such impairment occurs as a result of general football play or normal football heading. The neuropsychological consequences of football-related subconcussive effects await confirmatory investigation.

Head injury and posttraumatic movement disorders

WE REVIEW THE phenomenology, pathophysiology, pathological anatomy, and therapy of posttraumatic movement disorders with special emphasis on neurosurgical treatment options. We also explore possible links between craniocerebral trauma and parkinsonism. The cause-effect relationship between head injury and subsequent movement disorder is not fully appreciated. This may be related partially to the delayed appearance of the movement disorder. Movement disorders after severe head injury have been reported in 13 to 66% of patients. Although movement disorders after mild or moderate head injury are frequently transient and, in general, do not result in additional disability, kinetic tremors and dystonia may be a source of marked disability in survivors of severe head injury. Functional stereotactic surgery provides long-term symptomatic and functional benefits in the majority of patients. Thalamic radiofrequency lesioning, although beneficial in some patients, frequently is associated with side effects such as increased dysarthria or gait disturbance, particularly in patients with kinetic tremor secondary to diffuse axonal injury. Deep brain stimulation is used increasingly as an option in such patients. It remains unclear whether pallidal or thalamic targets are more beneficial for treatment of posttraumatic dystonia. Trauma to the central nervous system is an important causative factor in a variety of movement disorders. The mediation of the effects of trauma and the pathophysiology of the development of posttraumatic movement disorders require further study. Functional stereotactic surgery should be considered in patients with disabling movement disorders refractory to medical treatment.

Heading and head injuries in soccer

In the world of sports, soccer is unique because of the purposeful use of the unprotected head for controlling and advancing the ball. This skill obviously places the player at risk of head injury and the game does carry some risk. Head injury can be a result of contact of the head with another head (or other body parts), ground, goal post, other unknown objects or even the ball. Such impacts can lead to contusions, fractures, eye injuries, concussions or even, in rare cases, death. Coaches, players, parents and physicians are rightly concerned about the risk of head injury in soccer. Current research shows that selected soccer players have some degree of cognitive dysfunction. It is important to determine the reasons behind such deficits. Purposeful heading has been blamed, but a closer look at the studies that focus on heading has revealed methodological concerns that question the validity of blaming purposeful heading of the ball. The player's history and age (did they play when the ball was leather and could absorb significant amounts of water), alcohol intake, drug intake, learning disabilities, concussion definition and control group use/composition are all factors that cloud the ability to blame purposeful heading. What does seem clear is that a player's history of concussive episodes is a more likely explanation for cognitive deficits. While it is likely that the subconcussive impact of purposeful heading is a doubtful factor in the noted deficits, it is unknown whether multiple subconcussive impacts might have some lingering effects. In addition, it is unknown whether the noted deficits have any affect on daily life. Proper instruction in the technique is critical because if the ball contacts an unprepared head (as in accidental head-ball contacts), the potential for serious injury is possible. To further our understanding of the relationship of heading, head injury and cognitive deficits, we need to: learn more about the actual impact of a ball on the head, verify the exposure to heading at all ages and competitive levels, determine stable estimates of concussive injury rates across the soccer spectrum, conduct prospective longitudinal studies on soccer players focusing on exposure, injury and cognition, and determine the minimum safe age to begin instruction on the skill of heading. Only then will we be able to speak with some authority on the issue of heading and head injuries in soccer.

New frontiers in diagnostic imaging in concussive head injury

Concussed athletes may have documented incapacitating postconcussive symptoms, neuropsychological deficits, and consequent important changes in their lives and sport, yet the majority of neuroimaging attempts reveal few findings to account for these signs and symptoms. In this paper, we explore new techniques in the neuroimaging of concussion including diffusion-weighted magnetic resonance imaging and functional brain imaging technology.

Neuropsychological test performance prior to and following sports-related mild traumatic brain injury

OBJECTIVE

To examine the utility of neuropsychological tests in assessing college athletes prior to and following a sports-related mild Traumatic Brain Injury (mTBI).

DESIGN

A prospective study of college athletes who sustained mTBI while engaged in sport. Preinjury baseline neuropsychological test data were obtained for athletes at risk for mTBI. Following an mTBI, the athlete and his or her matched noninjured control were evaluated at 2 hours, 48 hours, 1 week, and I month postinjury.

SETTING

Male and female athletes from a Division I college.

PARTICIPANTS

Male and female athletes from the football, men's ice hockey, men's and women's soccer, and men's and women's basketball teams at Penn State University. A total of 29 injured and 20 noninjured athletes participated in the study.

INTERVENTIONS

Neuropsychological test batteries were administered at baseline and serially following mTBI.

MAIN OUTCOME MEASURES

Post-Concussion Symptom Checklist, Hopkins Verbal Learning Test, Symbol Digit Modalities Test, Stroop Color-Word Test, Trail Making Test, VIGIL/W, List Learning, Digit Span, Penn State Cancellation Test, and Controlled Oral Word Association.

RESULTS

Neuropsychological test data yielded significant differences between injured athletes and controls at 2 hours and 48 hours following cerebral concussion; injured athletes performing significantly worse than controls. Injured athletes reported a significantly greater number of postconcussion symptoms 2 hours following injury but not at the 48-hour assessment. No multivariate group differences were found at 1 week, but univariate analyses suggested significant differences on a few measures. At 1 month postinjury, a statistically significant difference was found on one measure with injured athletes marginally outperforming controls.

CONCLUSIONS

Neuropsychological tests are useful in the detection of cognitive impairment following mTBI. The test data appear to be more effective than subjective report of symptoms in differentiating between injured and noninjured athletes at 48 hours postinjury. Although significant individual variability existed, most injured athletes recovered within 1 week of injury. A battery of tests, rather than any single test, is necessary to capture the variability that exists among injured athletes.

Head injury in athletes

HEAD INJURIES INCURRED during athletic endeavors have been recorded since games were first held. During the last century, our level of understanding of the types of cerebral insults, their causes, and their treatment has advanced significantly. Because of the extreme popularity of sports in the United States and worldwide, the implications of athletic head injury are enormous. This is especially true considering the current realization that mild traumatic brain injury (MTBI) or concussion represents a major health consideration with more long-ranging effects than previously thought. When considering athletic injuries, people who engage in organized sports, as well as the large number of people who engage in recreational activities, should be considered. There are 200 million international soccer players, a group increasingly recognized to be at risk for MTBI. The participation in contact sports of a large number of the population, especially youth, requires a careful and detailed analysis of injury trends and recommended treatment. There are numerous characteristics of this patient population that make management difficult, especially their implicit request to once again be subjected to potential MTBI by participating in contact sports. Recent research has better defined the epidemiological issues related to sports injuries involving the central nervous system and has also led to classification and management paradigms that help guide decisions regarding athletes' return to play. We currently have methods at our disposal that greatly assist us in managing this group of patients, including improved recognition of the clinical syndromes of MTBI, new testing such as neuropsychological assessment, radiographic evaluations, and a greater appreciation of the pathophysiology of concussive brain injury. The potential for long-term consequences of repetitive MTBI has been recognized, and we no longer consider the "dinged" states of athletic concussions to have the benign connotations they had in the past. We review the historical developments in the recognition and care of athletes with head injuries, the current theory of the pathophysiology and biomechanics of these insults, and the recommended management strategy, including return-to-play criteria.

The postconcussion syndrome after mild head trauma: is brain damage overdiagnosed? Part 1

Many investigators attribute the postconcussion syndrome following mild closed head injury to permanent brain damage. The evidence supporting this conclusion is reviewed, including the force necessary to cause permanent brain damage; the basis for determining whether the patient was exposed to sufficient force in the accident to permanently damage the brain; the basis for determining whether the patient actually has permanent brain damage (not just brain dysfunction) traceable to the accident; and whether the location and severity of brain damage is sufficient to account for the postconcussion syndrome.

CONCLUSION

the evidence for permanent traumatic brain damage as the cause of the postconcussion syndrome following mild closed head injury is weak.

The acute neuropsychological effects of heading in soccer: a pilot study

OBJECTIVE

The main objective of this study was to prospectively examine the acute effects of heading in soccer on cognitive function.

DESIGN

This was a prospective cross-over study using a brief neuropsychological battery to assess cognitive function. The tests were performed before and after two separate practice sessions, with athletes serving as their own controls.

SETTING

Male and female Division I college athletes.

PARTICIPANTS

Members of the men's and women's varsity collegiate Penn State University soccer teams. Forty-four males and 56 females entered and finished the study. All athletes had a normal physical examination.

INTERVENTIONS

Before and after both practice sessions, all athletes had a brief battery of neuropsychological tests and a symptom checklist.

MAIN OUTCOME MEASURES

Neuropsychological tests symptom checklist compared at baseline with those after the practice sessions.

RESULTS

There were no significant differences in pretest scores between groups and no difference on posttest scores between heading and nonheading groups. A significant difference was detected using MANOVA (p = < 0.001) between pre- and posttest scores for measures of attention and concentration, indicating a practice effect. A gender-specific effect in one test measuring attention and concentration was found. There was no difference in symptoms before and after heading as compared with exertional controls.

CONCLUSIONS

In this study, soccer players heading the ball does not appear to lead to acute changes in cognitive function as assessed by a brief neuropsychological battery. There are practice effects that occur with repetitive neuropsychological testing and gender differences with certain tests.

Acute traumatic brain injury in amateur boxing

Via neuropsychological testing, this research team found post-match cognitive impairment in amateur boxers despite the fighters' use of headgear.

BACKGROUND

Acute traumatic brain injury (ATBI) represents the neurologic consequence of concussive and subconcussive blows to the head. Evidence suggests that ATBI may be associated with boxing and collision sports such as American football and soccer, thus potentially exposing millions of athletes annually.

OBJECTIVE

The objectives of this study were to determine whether significant ATBI occurs in boxers who compete and, if present, the nature of the cognitive impairment. A secondary objective was to determine if headgear could reduce the risk for ATBI in amateur boxing.

DESIGN

In this inception cohort study, 38 amateur boxers underwent neuropsychological examination before and shortly after a boxing match and were compared with a control group of 28 amateur boxers who were tested before and after a comparable physical test. The main outcome measures were neuropsychological tests (memory, mental and fine-motor speed, planning, and attention) proven to be sensitive to cognitive changes incurred in contact and collision sports.

RESULTS

The boxers who competed exhibited an ATBI pattern of impaired performance in planning, attention, and memory capacity when compared with controls. They had significantly different findings in the Categorization Task Test (P = 0.047); Digit Symbol Test (P = 0.02); Logical Memory: Short Term Memory and Long Term Memory subtests (both tests, P < 0.001); and Visual Reproduction: Short Term Memory subtest (P < 0.001) and Long Term Memory subtest (P < 0.03).

CONCLUSION

Participation in amateur boxing matches may diminish neurocognitive functioning despite the use of headgear. The neurocognitive impairment resembles cognitive symptoms due to concussions. Guidelines are needed to reduce the risk for repeated ATBI.

Heading the Ball in Soccer: What's the Risk of Brain Injury?

Concern exists that heading the ball in soccer may cause brain injury. Studies using EEG, CT, neurologic exams, and neuropsychological testing have not clearly established that the practice is hazardous. Studies generally have shown no neuropsychological differences between soccer players and other athletes, but some have revealed differences between soccer players and nonathletes. Because of the uncertainties, the authors advocate use of correct heading technique, enforcement of game rules, and increased awareness of the potential for injury from heading the ball.

Are brain injuries a significant problem in soccer?

This article examines the types of forces that the brain is subjected to in soccer, secondary to both acute brain injury and repetitive heading of the ball. The incidence of acute brain injury is reviewed, as well as studies documenting the effects of heading the ball. Finally, 10 actions are proposed that would make soccer a safer sport with respect to brain injuries and provide avenues for further study in this area.

Concussion history in elite male and female soccer players

A unique feature of soccer is the purposeful use of the head for controlling, passing, and shooting a soccer ball. Some concern has been expressed in the literature on the cumulative effects of heading on soccer players. Certain neurophysiologic and neuropsychologic changes have been reported in current or retired players, with heading being blamed. A major factor that could influence some of the findings is a player's history of concussive episodes, which are known to influence brain function. These episodes can occur during aspects of the game other than heading. We interviewed all male and female soccer players (N = 137, average age = 20.5 years) who competed at the U.S. Olympic Sports Festival in 1993. The mechanisms of injuries, frequency, and sequelae were determined. There were 74 concussions in 39 male players (grade I = 50) and 28 concussions in 23 female players (grade I = 19). For the men, 48 of the 74 episodes were from collisions with another player. For the women, 20 of 28 were from such collisions. Headaches, being "dazed," and dizziness were the most common symptoms reported. Based on concussion history, the odds are 50% that a man, and 22% that a woman, will sustain a concussion within a 10-year period. The data indicate that concussions from player-to-player contact are a frequent hazard in soccer. Head injuries incurred this way may be more of an influence for published findings of physiologic and psychologic deficiencies than routine heading of the soccer ball.

Concussion incidence in elite college soccer players

A unique aspect of soccer is the use of the head for directing the ball. The potential for resultant head injuries has been the focus of discussions worldwide. Prior work has attributed neuropsychologic deficits to the cumulative effects of heading, without evaluating concussion rates in soccer players. We prospectively studied the seven men's and eight women's varsity soccer teams in the Atlantic Coast Conference during two seasons to document concussion incidence. The 29 concussions diagnosed over the 2 years in 26 athletes, 17 (59%) concussions in men and 12 (41%) in women, resulted from contact with an opponent's head (8, 28%), elbow (4, 14%), knee (1, 3%), or foot (1, 3%); the ball (7, 24%); the ground (3, 10%); concrete sidelines (1, 3%); goalpost (1, 3%); or a combination of objects (3, 10%). Twenty concussions (69%) occurred in games; none resulted from intentional heading of the ball. The basic incidence was 0.96 concussions per team per season. The overall incidence was 0.6 per 1000 athlete-exposures for men, and 0.4 per 1000 athlete-exposures for women. By concussion grade, there were 21 (72%) grade 1, 8 (28%) grade 2, and no grade 3 concussions. These findings suggest that concussions are more common in soccer than anticipated and that acute head injuries may have potential for long-term neuropsychologic changes.

Acute and chronic brain injury in United States National Team soccer players

We designed a study to determine whether chronic encephalopathy occurs in elite, active soccer players resulting from repetitive heading of the soccer ball. Studies have suggested that the cumulative effects of heading a ball can cause a chronic brain syndrome similar to dementia pugilistica, which is seen in professional boxers. Twenty of 25 members of the U.S. Men's National Soccer Team training camp (average age, 24.9; average years of soccer, 17.7), who completed a questionnaire on head injury symptoms and had magnetic resonance imaging of the brain, were compared with 20 age-matched male elite track athletes. The soccer players were surveyed about playing position, teams, number of headers, acute head injuries, and years of playing experience. An exposure index to headers was developed to assess a dose-response effect of chronic heading. The soccer and track groups were questioned regarding alcohol use and history of acute head traumas. Questionnaire analysis and magnetic resonance imaging demonstrated no statistical differences between the two groups. Among the soccer players, symptoms and magnetic resonance imaging findings did not correlate with age, years of play, exposure index results, or number of headers. However, reported head injury symptoms, especially in soccer players, correlated with histories of prior acute head injuries (r = 0.63). These findings suggest that any evidence of encephalopathy in soccer players relates more to acute head injuries received playing soccer than from repetitive heading.

The neuropsychiatric aspects of boxing

OBJECTIVE

To review the neuropsychiatry of boxing.

METHOD

This update considers the clinical, neuropsychological, diagnostic, neurobiological, and management aspects of boxing-related brain injury.

RESULTS

Professional boxers with multiple bouts and repeated head blows are prone to chronic traumatic encephalopathy (CTE). Repeated head blows produce rotational acceleration of the brain, diffuse axonal injury, and other neuropathological features. CTE includes motor changes such as tremor, dysarthria, and parkinsonism; cognitive changes such as mental slowing and memory deficits; and psychiatric changes such as explosive behavior, morbid jealousy, pathological intoxication, and paranoia. Screening with neuropsychological tests and neuroimaging may help predict those boxers at risk for CTE.

CONCLUSIONS

Boxing results in a spectrum of CTE ranging from mild, nonprogressive motor changes to dementia pugilistica. Recent emphasis on safety in the ring, rehabilitation techniques, and other interventions do not eliminate the risk for CTE. For this reason, there is an active movement to ban boxing.