Athletic exposure to repetitive brain trauma and its effect on the development of chronic traumatic encephalopathy

Thesis (Ph.D.)--Boston UniversityChronic Traumatic Encephalopathy (CTE) is a neurodegenerative disease marked by widespread accumulation of hyperphosphorylated tau (ptau). CTE is associated with a constellation of symptoms, including impairments in cognition, behavior, and mood. Although initially described in boxers as dementia pugilistrca, CTE has been diagnosed in athletes from a variety of backgrounds, as well as military veterans and other individuals exposed to traumatic brain injury (TBI). To date, the only shared risk factor for CTE is a history of single or multiple TBI. This work aimed to better elucidate the relationship between exposure to head impacts and the development and progression of CTE. Although the link between brain injury and CTE has been well described, the magnitude of this relationship has never been studied epidemiologically. The minimum prevalence of CTE was determined in a cohort at high risk of exposure to head impacts, specifically National Football League (NFL) athletes. All former NFL athletes who passed away in 2011 were identified; a subset of these athletes were studied and diagnosed with CTE to establish a minimum prevalence of CTE. The characteristics of those examined and diagnosed with CTE and those undiagnosed were explored. These analyses represent the first epidemiologic study of CTE; the high prevalence highlights the relationship between exposure to head impacts and the diagnosis of CTE. Next, the relationship between the nature of athletic exposure and CTE was quantified. An athletic history questionnaire was developed and integrated into a mathematical model, incorporating data from sensors placed in football players' helmets, to identify the theoretical frequency and magnitude of an athlete's head impact exposure. This model was adapted for use postmortem, and it was found that the duration of athletic exposure, total theoretical collisions experienced; and the sum of the 95th percentiles of the rotational acceleration endured, were all significantly associated with extent of CTE pathology. The relationships between the type of athletic exposure and the clinical presentation of disease and the specific neuroanatomic distribution of p-tau were also explored. These findings indicate the significant role of athletic exposure to head impacts on the diagnosis and progression of CTE, clinically and pathologically

Cognitive and emotional effects of one season of head impact exposure in high school contact sport athletes

Short-term and long-term neurological damage as a result of sports-related brain trauma is a major concern for athletes today. In the last decade, studies of subconcussive repetitive head impacts (RHI) in contact sports have found associations with functional and structural brain changes, even in the absence of diagnosed concussion. Risk and thresholds for brain dysfunction in the setting of sports-related RHI remain poorly understood. This prospective study enrolled 119 athletes (72 contact, 47 noncontact) of both sexes (79 male, 40 female), to explore the effect of one season of subconcussive RHI on brain function in high school football, boys lacrosse, and boys and girls soccer versus a comparison group of noncontact athletes. This study is the first to assess the effects of one season of RHI exposure on traditional and novel cognitive measures as well as self-reported emotion, sleep and headache in high school athletes. Contact sport athletes wore a commercial accelerometer to investigate if there is a dose-response relationship between RHI exposure and brain function. Paired t-test comparisons of all measures revealed contact sport athletes were not different than noncontact athletes in experiencing negative changes over the course of one season on the assessment battery. Given the number of subjects evaluated and the resultant power to detect change, this study had an 82.5% power to detect a Cohenʼs d of 0.66. Regression analysis of multiple measures of RHI among contact sport athletes did not identify a significant relationship between exposure and changes in cognition, emotion, sleep or headache over one season. Secondary analyses found significant relationships between a greater number of total head impacts at postseason assessment and higher scores on NIH Emotion Battery elements Perceived Stress (p=0.0002) and Perceived Hostility (p=0.0004), but it was unrelated to total years of football exposure. Overall, this study showed that there does not appear to be an association between one season of RHI exposure and short-term changes in cognition or self-reported aspects of emotion, sleep, or headache. Results from this study may help in the design of future investigations that will increase our understanding of the short-term consequences of RHI. Future studies should concentrate on the question of a clinically significant threshold at which RHI above a certain magnitude is more likely to cause brain dysfunction

Washington University Record, January 25, 2007

https://digitalcommons.wustl.edu/record/2094/thumbnail.jp

The use of linear and nonlinear methods for evaluating balance on collegiate men???s and women???s ice hockey teams throughout a season

If objective data from balance assessments are to be used in assessing player???s for returning to play, it is necessary to understand the in-season variability that can occur. The purpose of this work was to determine if the time evolving nature of these measures can reveal insights, that more effective return-to-lay guidelines can be stablished. Forty-six varsity ice hockey players participated during the 2014-15 season. All underwent baseline measurements and were tested ever 4 weeks throughout the season, plus one post-season session. Dependent linear (mean power frequency, mean velocity, and total excursion) and nonlinear (approximate entropy) measures were used to interpret force plate data. Linear and nonlinear measures both showed significant main effects of time. Monthly testing throughout the season demonstrated decreases in mean values for all measures with respect to baseline. In-season variability of balance postures recorded can be used when comparing concussed athlete???s baseline measures to post-concussion measures

The Interrelationships Among a Concussion-Related Biomarker, Head Hits, And ImPACT Test In Collegiate Football Players

Head injuries are prevalent in collegiate athletics with concussions being common among contact sports, such as football. Concussion assessment and diagnosis is complicated by the lack of objective and assessment techniques. The purpose of the study was to determine if there is a relationship between the level of a concussion-related biomarker, self-report (subjective) head hits, video-analyzed head hits, and ImPACT test scores in college football athletes before and after a football practice session. After being recruited and consented to participate, 29 Division I college football athletes provided a blood sample via finger stick two days before a 2014 spring football season practice and within within 4 hours post-practice. The blood samples were processed to generate serum samples, and these serum samples were tested using a S100B ELISA kit to measure the amount of S100B. A computerized concussion diagnosis test (ImPACT) was completed by each subject before and after the practice. Video recordings of the practice were used to objectively count the number of hits that each participant sustained during the practice. The major results are as follows. None of the participants suffered a concussion based on current diagnostic concussion assessments, including a symptom checklist, Standardized Assessment of Concussion (SAC), and Balance Error Scoring System (BESS). The participant who suffered head hits (as determined by video review) during practice had a serum S100B level that increased from 39.5 pg/ml pre-practice to 85.3 pg/ml post-practice. In comparison, three other participants who did not sustain head hits (as determined by video review) had decreased or a minimal increase in the serum S100B level. Due to the limited number of samples (15 out of 76) that had a CV \u3c 15%, the relationships between biomarker difference scores and head hits and ImPACT scores were not conducted. However, the relationship between video-analyzed head hits and the five ImPACT test composite scores was a negative correlation: r = -0.10, p = 0.29; r = -0.11, p \u3c 0.01; r = -0.17, p = 0.02; r = -0.01, p = In conclusion, an increased serum S100B level may be linked to sub-concussive head hits during collegiate football practice. Because an increase in serum S100B level likely represents trauma to the brain, sub-concussive hits may cause mild brain injury. The major clinical implication of this study\u27s findings relates to the objective clinical data that an athletic trainer needs for diagnosing brain trauma. For an athletic trainer to provide comprehensive care to football players, the athletic trainer needs objective clinical data, such as biomarker data. However, the collection of blood samples on the sidelines is a challenge. Based on this study\u27s findings, the collection of blood via finger stick is feasible. Therefore, in the future, the athletic trainer might be able to obtain biomarker data to aid in the diagnosis of brain trauma

An investigation into mild traumatic brain injury identification, management, and mitigation

Concussion is classified as a mild traumatic brain injury which can be induced by biomechanical forces such as a physical impact to the head or body, which results in a transient neurological disturbance without obvious structural brain damage. Immediate access to tools that can identify, diagnosis and manage concussion are wide ranging and can lack consistency in application. It is well documented that there are frequent incidences of concussion across amateur and professional sport such as popular contact sports like rugby union. A primary aim of this thesis was to establish the current modalities of ‘pitch side’ concussion management, identification, and diagnosis across amateur and professional sporting populations. Furthermore, the research sought to understand existing concussion management and concussion experiences by means of recording the player’s experiences and perceptions (retired professional rugby union players). These qualitative studies sought to gain insights into concussion experiences, the language used to discuss concussion and the duty of care which medical staff, coaching personnel, and club owners have towards professional rugby players in their employment. In addition, possible interventions to reduce the incidence of concussion in amateur and professional sports were investigated. These included a ‘proof of concept’ using inertial measurement units and a smartphone application, a tackle technique coaching app for amateur sports. Other research data investigating the use of neurological function data and neuromuscular fatigue in current professional rugby players as a novel means of monitoring injury risk were included in this research theme. The findings of these studies suggest that there is an established head injury assessment process for professional sports. However, in amateur sport settings, this is not the existing practice and may expose amateur players to an increased risk of post-concussion syndrome or early retirement. Many past professional rugby union players stated that they did not know the effects of cumulative repetitive head impacts. They discussed how they minimised and ignored repeated concussions due to peer pressure or pressure from coaches or their own internal pressures of maintaining a livelihood. These data suggest that players believed that strong willed medical staff, immutable to pressures from coaching staff or even athletes themselves, were essential for player welfare and that club owners have a long-term duty of care to retired professional rugby union players. However, there are anecdotal methods suggested to reduce concussion incidence. For example, neck strengthening techniques to mitigate against collision impacts. There is, no longitudinal evidence to suggest that neck strength can reduce the impacts of concussion in adult populations . Additionally, other factors such as lowering the tackle height in the professional and amateur game is currently being investigated as a mitigating factor to reduce head injury risk. The final theme of the thesis investigated possible methods to reduce injury incidence in amateur and professional athletes. The novel tackle technique platform could assist inexperienced amateur coaches on how to coach effective tackle technique to youth players. The findings from the neurological function data suggests that this may be an alternative way for coaches to assess and gather fatigue data on professional rugby union players alongside additional subjective measures and neuromuscular function data. Recently, the awareness of concussion as an injury and the recognition of concussion in many sports settings has improved. These incremental improvements have led to increased discussion regarding possible measures to mitigate the effects of concussion. There are many additional procedures to be implemented before a comprehensive concussion management is universally available, particularly in amateur and community sports. These necessary processes could be technological advances (e.g., using smart phone technology) for parents and amateur coaches to assist in the early identification of concussion or evidence-based concussion reduction strategies

Impact of Head Injury on Cognitive Functioning and Social Cognition in UK-based Female Rugby Players

Introduction: Increasing attention is focused on the potential long-term impact of sports-related mild traumatic brain injuries (SRmTBI). Evidence suggests poorer cognitive and psychosocial outcomes in SRmTBI, including increased risk of developing certain neurodegenerative conditions. Research to date has focused on males neglecting female athletes, despite evidence suggesting sex-specific differences in frequency and recovery of SRmTBI. Aims: To explore the association between SRmTBI and cognitive functioning with a specific focus on social cognition in female rugby players. Method: A quantitative cross-sectional design was employed allowing for thirteen female rugby players with a history of SRmTBI to complete a neuropsychological battery of general cognitive functioning and social cognition. Results: Weaknesses relative to normative data, were found for domains of social cognition including theory of mind and cognitive empathy, despite typical scores on domains of general cognitive functioning relative to normative data. Group level analysis confirmed poorer performance for theory of mind and cognitive empathy measures in contrast to overall performance on domains of general cognitive functioning. Discussion: Findings from this preliminary study indicate that measures of social cognition should be incorporated into routine assessment and management of SRmTBI. Further research is needed to investigate the association between social cognition and SRmTBI