A systematic review of potential long-term effects of sport-related concussion

Analysis of Concussions Reported in American Professional Football Injury Reports in the 2019 Through 2023 Regular Seasons

OBJECTIVE

The National Football League (NFL) has seen increasing scrutiny regarding its management of concussions, especially following an on-field incident involving the Miami Dolphins' quarterback Tua Tagovailoa in the 2022 season. We hope to elucidate the recent trends in the diagnosis and management of concussions during the course of 5 NFL seasons from 2019 to 2023.

METHODS

We queried the NFL injury reports from the 2019 through 2023 database recording players listed with concussions. The weeks missed were calculated using the NFL game logs. Players' concussions that did not occur in the games, those complicated by other injuries, and those affected by roster status were excluded.

RESULTS

Searches of the NFL injury reports resulted in the identification of 664 of 692 concussions (96%) that occurred in regular season games across the 2019-2023 seasons. During the course of these 5 seasons, 31% of the players returned without missing a game, 39% of the players missed 1 game, and 30% of the players missed ≥2 games. No significant difference in the number of concussions per game or weeks missed was observed across the seasons observed. Players with concussions on teams that made the playoffs saw fewer weeks missed than those on non-playoff teams (0.86 vs. 1.37; P = 0.002).

CONCLUSIONS

Since the start of the 2021 NFL season, an increasing incidence of concussions has been noted; however, there was no change observed in the number of weeks missed after the concussions. Trends in the rates of concussions across the seasons remain largely stable, despite increased scrutiny over concussions in the sport.

Functional connectivity changes in neurodegenerative biomarker-positive athletes with repeated concussions

Multimodal biomarkers may identify former contact sports athletes with repeated concussions and at risk for dementia. Our study aims to investigate whether biomarker evidence of neurodegeneration in former professional athletes with repetitive concussions (ExPro) is associated with worse cognition and mood/behavior, brain atrophy, and altered functional connectivity. Forty-one contact sports athletes with repeated concussions were divided into neurodegenerative biomarker-positive (n = 16) and biomarker-negative (n = 25) groups based on positivity of serum neurofilament light-chain. Six healthy controls (negative for biomarkers) with no history of concussions were also analyzed. We calculated cognitive and mood/behavior composite scores from neuropsychological assessments. Gray matter volume maps and functional connectivity of the default mode, salience, and frontoparietal networks were compared between groups using ANCOVAs, controlling for age, and total intracranial volume. The association between the connectivity networks and sports characteristics was analyzed by multiple regression analysis in all ExPro. Participants presented normal-range mean performance in executive function, memory, and mood/behavior tests. The ExPro groups did not differ in professional years played, age at first participation in contact sports, and number of concussions. There were no differences in gray matter volume between groups. The neurodegenerative biomarker-positive group had lower connectivity in the default mode network (DMN) compared to the healthy controls and the neurodegenerative biomarker-negative group. DMN disconnection was associated with increased number of concussions in all ExPro. Biomarkers of neurodegeneration may be useful to detect athletes that are still cognitively normal, but with functional connectivity alterations after concussions and at risk of dementia.

Mapping the institutionalization of racism in the research about race and traumatic brain injury rehabilitation: implications for Black populations

PURPOSE

Traumatic brain injury (TBI) is a chronic disease process and a public health concern that disproportionately impacts Black populations. While there is an abundance of literature on race and TBI outcomes, there is a lack of scholarship that addresses racism within rehabilitation care, and it remains untheorized. This article aims to illuminate how racism becomes institutionalized in the scientific scholarship that can potentially inform rehabilitation care for persons with TBI and what the implications are, particularly for Black populations.

MATERIAL AND METHODS

Applying Bacchi's What's the Problem Represented to be approach, the writings of critical race theory (CRT) are used to examine the research about race and TBI rehabilitation comparable to CRT in other disciplines, including education and legal scholarship.

RESULTS

A CRT examination illustrates that racism is institutionalized in the research about race and TBI rehabilitation through colourblind ideologies, meritocracy, reinforcement of a deficit perspective, and intersections of race and the property functions of whiteness. A conceptual framework for understanding institutional racism in TBI rehabilitation scholarship is presented.

CONCLUSIONS

The findings from this article speak to the future of TBI rehabilitation research for Black populations, the potential for an anti-racist agenda, and implications for research and practice.

Repeat traumatic brain injury exacerbates acute thalamic hyperconnectivity in humans

Repeated mild traumatic brain injury is of growing interest regarding public and sporting safety and is thought to have greater adverse or cumulative neurological effects when compared with single injury. While epidemiological links between repeated traumatic brain injury and outcome have been investigated in humans, exploration of its mechanistic substrates has been largely undertaken in animal models. We compared acute neurological effects of repeat mild traumatic brain injury (n = 21) to that of single injury (n = 21) and healthy controls (n = 76) using resting-state functional MRI and quantified thalamic functional connectivity, given previous identification of its prognostic potential in human mild traumatic brain injury and rodent repeat mild traumatic brain injury. Acute thalamocortical functional connectivity showed a rank-based trend of increasing connectivity with number of injuries, at local and global scales of investigation. Thus, history of as few as two previous injuries can induce a vulnerable neural environment of exacerbated hyperconnectivity, in otherwise healthy individuals from non-specialist populations. These results further establish thalamocortical functional connectivity as a scalable marker of acute injury and long-term neural dysfunction following mild traumatic brain injury.

Broadening our understanding of injury mechanisms to include at-risk situations: an overview of potential injuries at the FIFA men's World Cup Qatar 2022TM

This study aims to examine and describe the characteristics of potential injury situations during a men's professional international tournament quantified using the FIFA Football Language Medical Coding. A prospective study was conducted during the 64 matches of the FIFA World Cup Qatar 2022™, during which five analysts recorded potential injury situations from video analysis. "Potential injuries" were recorded when players stayed down > 5 s and/or requested medical attention. Characteristics were further recorded for variables such as opponent's action and body location. In total, 720 potential injury situations were recorded of which 139 required medical assessment. The actions which resulted in most potential injuries were running while receiving a pass (74; 10%), while passing the ball (59; 8%), and while progressing with the ball (48; 7%). Duels and ball progression led to a potential injury in 3.0% and 2.1% of all similar actions in total. Both aerial duels and ball progression led to an potential injury that required medical assessment on 0.4% of occasions. Most potential injuries involved the head (149; 21%), foot (120; 17%), or lower leg (110; 15%) with most medical assessments of the head (35; 25%), lower leg (17; 12%), and knee (15; 11%) with a median duration of 47 seconds (IQR 28-61). This study provides a detailed overview of match circumstances that may have a higher injury risk. Although some variables within the coding system need improvement to increase reliability, its use will allow a more detailed comparison of differences between high-risk player actions leading to injury and those that do not, which can improve future prevention strategies.

High school rugby coaches' knowledge and opinions of concussion in Kwa-Zulu Natal province in South Africa: an ecological cross-sectional study

BACKGROUND

Concussions in Rugby Union are common with an increased risk to adolescent players. Coaches are key to injury prevention and a greater understanding of their knowledge and sentiments may guide future initiatives. There is a lack of data on rugby coaches, especially in South Africa. This study aimed to investigate the knowledge and opinions of high school rugby coaches regarding concussion management.

METHODS

This cross-sectional study of 37 high school rugby coaches in South Africa, was conducted via a self-reported questionnaire. Concussion knowledge was scored for correct answers only with closed-question scaling methods to measure the importance of items of concussion management using a graphical rating scale. An attitude scale (Likert) was used to assess self-reported opinions and behaviours. Associations were calculated for participant characteristics and overall concussion injury knowledge.

RESULTS

More participants showed good overall knowledge of ≥ 75% (n = 22, 59% vs. n = 15, 40%), especially those with greater coaching experience (p = 0.021). Player welfare was perceived more important than player performance (185 vs. 164), with concussion prevention most important (184 of 185). Appealing characteristics of an injury prevention programme were the improvement of player skill (173, SD ± 0.75, mean 4.68), being adaptable (171, ± 0.86, 4.62), and being completed in the warm-up (167, ± 0.93, 4.51). The biggest perceived barriers were duration (138, ± 1.59, mean 3.73), effort (130, ± 1.56, 3.51), compliance and lack of knowledge (both 127, ± 1.68, 3.43).

CONCLUSION

These results support the implementation of ongoing concussion education for rugby coaches and identify areas for promoting awareness and knowledge of concussion injury prevention, identification, and specific management of younger athletes. Appealing characteristics and barriers are highlighted and may allow for improved implementation and adherence to concussion prevention programmes.

Risk factors and service gaps affecting a sustainable work: a qualitative multi-stakeholder analysis in the context of persons with acquired brain injury living in Switzerland

INTRODUCTION

Along with the social and economic challenges posed by an aging society, creating work conditions that allow persons to stay healthy and work into old age has become a major task of Western societies. Retaining employment after returning to work is particularly difficult for individuals with a disability, as evidenced by the high rate of premature labor market dropout. Individuals with acquired brain injury (ABI) exemplify this challenge, as it often impairs cognitive, technical, and interpersonal abilities that are crucial in today's labor market. To effectively support these individuals, vocational integration practitioners require comprehensive knowledge of risk factors for premature labor market dropout and effective strategies for sustainable work.

OBJECTIVE

This study aimed to identify perceived risk factors and related service gaps regarding sustainable work for people with ABI, as reported by affected individuals, employers, vocational integration professionals, and health professionals.

METHODS

Secondary data analysis. Data that was originally collected through seven focus groups and two interviews with persons with ABI, 15 interviews with employers, and 13 interviews with vocational integration and health professionals in the context of the project 'Sustainable employment' was re-analysed thematically.

RESULTS

Two major themes of risk factors were identified: (1) person-related factors (including the subthemes: post-ABI impairments; lack of understanding of post-ABI impairments; poor health management) and (2) environment-related factors (including the subthemes: challenges related to the service structure; insufficient knowledge and education about ABI; challenges at the workplace; difficulties in private life). While stakeholders noted the variety of the currently available services, they particularly pointed to the missing long-term monitoring and counseling services for persons with ABI following the initial return-to-work, reflecting a major challenge for sustainable work. An overarching gap related to the fragmentation of the service structure and the lack of case coordination along the working life.

CONCLUSIONS

Multiple stakeholders emphasized the importance of empowering individuals, ensuring easy access to professional support, and providing a suitable work environment to address key risk factors and facilitate sustainable work for individuals with ABI. Continuous coaching, long-term monitoring and counseling following return-to-work, were identified as potential strategies to achieve these goals.

Neurocognitive Function Domains Are Not Affected in Active Professional Male Footballers, but Attention Deficits and Impairments Are Associated with Concussion

OBJECTIVE

To determine the neurocognitive function of active professional male footballers, determine whether deficits/impairments exist, and investigate the association between previous concussion(s) and neurocognitive function.

METHODS

An observational cross-sectional study conducted via electronic questionnaires. The CNS Vital Signs online testing system was used to evaluate neurocognitive function.

RESULTS

Of the 101 participants, 91 completed the neurocognitive function testing. Neurocognitive function domain deficits or impairments were unlikely in 54.5-89.1%, slight in 5.9-21.8%, moderate in 1.0-9.9%, and likely in 4.0-14.9% of participants. A history of zero concussions found a significant association between the neurocognitive index (Odds Ratio [OR] 0.6; 95% CI 0.2-0.4) and complex attention domain (OR 0.3; 95% CI 0.1-0.9), with 40% and 70% less odds, respectively, of deficit/impairment. Among the 54.5% who reported any number of concussions, there were increased odds of neurocognitive domain deficits/impairments for complex attention (CA) [3.4 times more] and simple attention (SA) [3.1 times more].

CONCLUSION

In the active professional male footballer, most neurocognitive functions do not have significant deficits/impairments. The odds of neurocognitive function deficit/impairment were significantly increased threefold for CA and SA in those who reported a history of any concussion(s).

ZL006 mitigates anxiety-like behaviors induced by closed head injury through modulation of the neural circuit from the medial prefrontal cortex to amygdala

Closed head injury is a prevalent form of traumatic brain injury with poorly understood effects on cortical neural circuits. Given the emotional and behavioral impairments linked to closed head injury, it is vital to uncover brain functional deficits and their driving mechanisms. In this study, we employed a robust viral tracing technique to identify the alteration of the neural pathway connecting the medial prefrontal cortex to the basolateral amygdala, and we observed the disruptions in neuronal projections between the medial prefrontal cortex and the basolateral amygdala following closed head injury. Remarkably, our results highlight that ZL006, an inhibitor targeting PSD-95/nNOS interaction, stands out for its ability to selectively reverse these aberrations. Specifically, ZL006 effectively mitigates the disruptions in neuronal projections from the medial prefrontal cortex to basolateral amygdala induced by closed head injury. Furthermore, using chemogenetic approaches, we elucidate that activating the medial prefrontal cortex projections to the basolateral amygdala circuit produces anxiolytic effects, aligning with the therapeutic potential of ZL006. Additionally, ZL006 administration effectively mitigates astrocyte activation, leading to the restoration of medial prefrontal cortex glutamatergic neuron activity. Moreover, in the context of attenuating anxiety-like behaviors through ZL006 treatment, we observe a reduction in closed head injury-induced astrocyte engulfment, which may correlate with the observed decrease in dendritic spine density of medial prefrontal cortex glutamatergic neurons.

Medico-legal implications of dementia following concussion in rugby football

There is litigation in respect of dementia in ex-rugby football players. The allegation is that these ex-players have suffered a traumatic encephalopathy syndrome causing dementia and other neurological problems. The syndrome is alleged to have been caused by repeated concussion during play. It is alleged that governing bodies of rugby should have been aware, and players should have been warned, of this risk. The dilemma, for both claimants and defendants, is that there is no agreed definition of the syndrome nor are there any diagnostic tests that confirm or refute this diagnosis. This paper reviews the literature of traumatic encephalopathy syndrome and when governing bodies were aware of the possibility of rugby concussion causing dementia. The legal principles are discussed and a framework for determining the probability of an ex-rugby player having the syndrome is proposed.

Examining the role of depression on the relationship between performance-based and self-reported cognitive functioning after sport-related concussion

OBJECTIVE

Little is known about the relationship between neuropsychological test performance, cognitive symptom reporting, and depressive symptoms after sport-related concussion. Accordingly, this cross-sectional study examined these relationships in collegiate athletes. It was hypothesized that depressive symptoms would moderate and mediate the relationship between performance-based and self-reported cognitive functioning after concussion.

METHODS

After sustaining a sport-related concussion, 110 collegiate athletes completed a neuropsychological battery, the Post-Concussion Symptoms Scale, and the Beck Depression Inventory-Fast Screen. Neuropsychological test performance, depressive symptoms, and their interactions were entered into distinct hierarchical linear regression analyses with self-reported cognition as the dependent variable to assess moderation. Mediation was analyzed using the PROCESS macro with 5000 bootstrap samples and a 95% confidence interval.

RESULTS

There was a significant interaction between the mean memory composite and depressive symptoms when predicting cognitive symptom reporting, p = 0.047. Simple effects tests revealed that for athletes who had a lower memory composite score, an increase in depressive symptoms led to an increase in self-reported cognitive dysfunction, p < 0.001, ηp2 = 0.11. Depressive symptoms partially mediated the relationship between the memory composite and cognitive symptom reporting, indirect effect = -0.26, 95%CI[-0.58,0.001], but this relationship was not found for any other neurocognitive domain.

CONCLUSIONS

For tests of memory, depressive symptoms moderated and partially mediated the relationship between performance-based and self-reported cognitive functioning after sport-related concussion. Athletes reporting high depressive symptoms and cognitive dysfunction may need more comprehensive evaluations to inform return-to-play decisions, and depression could be a treatment target for athletes who report high levels of cognitive dysfunction after concussion.

[Repeated mild traumatic brain injury in the parietal cortex inhibits expressions of NLG-1 and PSD-95 in the medulla oblongata of mice]

OBJECTIVE

To assess the effects of repeated mild traumatic brain injury (rmTBI) in the parietal cortex on neuronal morphology and synaptic plasticity in the medulla oblongata of mice.

METHODS

Thirty-two male ICR mice were randomly divided into sham operation group (n=8) and rmTBI group (n=24). The mice in the latter group were subjected to repeated mild impact injury of the parietal cortex by a free-falling object. The mice surviving the injuries were evaluated for neurological deficits using neurological severity scores (NSS), righting reflex test and forced swimming test, and pathological changes of the neuronal cells in the medulla oblongata were observed with HE and Nissl staining. Western blotting and immunofluorescence staining were used to detect the expressions of neuroligin 1(NLG-1) and postsynaptic density protein 95(PSD-95) in the medulla oblongata of the mice that either survived rmTBI or not.

RESULTS

None of the mice in the sham-operated group died, while the mortality rate was 41.67% in rmTBI group. The mice surviving rmTBI showed significantly reduced NSS, delayed recovery of righting reflex, increased immobility time in forced swimming test (P < 0.05), and loss of Nissl bodies; swelling and necrosis were observed in a large number of neurons in the medulla oblongata, where the expression levels of NLG-1 and PSD-95 were significantly downregulated (P < 0.05). The mice that did not survive rmTBI showed distorted and swelling nerve fibers and decreased density of neurons in the medulla oblongina with lowered expression levels of NLG-1 and PSD-95 compared with the mice surviving the injuries (P < 0.01).

CONCLUSION

The structural and functional anomalies of the synapses in the medulla oblongata may contribute to death and neurological impairment following rmTBI in mice.

Widespread White Matter Abnormalities in Concussed Athletes Detected by 7T Diffusion Magnetic Resonance Imaging

Sports-related concussions may cause white matter injuries and persistent post-concussive symptoms (PPCS). We hypothesized that athletes with PPCS would have neurocognitive impairments and white matter abnormalities that could be revealed by advanced neuroimaging using ultra-high field strength diffusion tensor (DTI) and diffusion kurtosis (DKI) imaging metrics and cerebrospinal fluid (CSF) biomarkers. A cohort of athletes with PPCS severity limiting the ability to work/study and participate in sport school and/or social activities for ≥6 months completed 7T magnetic resonance imaging (MRI) (morphological T1-weighed volumetry, DTI and DKI), extensive neuropsychological testing, symptom rating, and CSF biomarker sampling. Twenty-two athletes with PPCS and 22 controls were included. Concussed athletes performed below norms and significantly lower than controls on all but one of the psychometric neuropsychology tests. Supratentorial white and gray matter, as well as hippocampal volumes did not differ between concussed athletes and controls. However, of the 72 examined white matter tracts, 16% of DTI and 35% of DKI metrics (in total 28%) were significantly different between concussed athletes and controls. DKI fractional anisotropy and axial kurtosis were increased, and DKI radial diffusivity and radial kurtosis decreased in concussed athletes when compared with controls. CSF neurofilament light (NfL; an axonal injury marker), although not glial fibrillary acidic protein, correlated with several diffusion metrics. In this first 7T DTI and DKI study investigating PPCS, widespread microstructural alterations were observed in the white matter, correlating with CSF markers of axonal injury. More white matter changes were observed using DKI than using DTI. These white matter alterations may indicate persistent pathophysiological processes following concussion in sport.

Quality Criteria for Studies Assessing the Acute Effects of Heading: Results from a UEFA Expert Panel

There is increasing concern regarding the effects of heading in football on brain health including cognitive, behavioural and neuromotor function, with research suggesting an association between repeated ball-head impacts and neurodegenerative disease. While longitudinal studies to determine the long-term consequences of heading are challenging, there have been short-term 'acute' studies conducted, with some studies lacking appropriate methodology to ensure valid results. The Union of European Football Associations (UEFA) established a panel of experts to determine methodological recommendations for the conduct of studies that explore the acute effects of heading (defined as a single session of heading conducted either in a laboratory setting or following match play or a training session). The aim of this panel was to create quality criteria for acute heading studies that will form part of the eligibility assessment when applying for UEFA research funding (although the criteria can be applied to the conduct of acute heading research more widely). This process was deemed necessary to counter studies with poor methodological quality that used heading trials that did not accurately represent player exposure to ball-head impacts through football practice and match play (such as small sample sizes, unrealistically high heading exposure, and a lack of consideration of confounding variables). The panel identified core design decisions that authors should consider when designing and conducting acute heading research, with key methodological requirements for each domain pertaining to participants, heading trials, confounding variables, statistics and dependent/target variables and their measurement. After two rounds of reviews, the final list of quality criteria was agreed by the panel and will be applied to the next round of UEFA grant applications.

Does Headgear Prevent Sport-Related Concussion? A Systematic Review and Meta-Analysis of Randomized Controlled Trials Including 6311 Players and 173,383 Exposure Hours

CONTEXT

A sport-related concussion (SRC) is a traumatic brain injury that is caused by biomechanical stresses and results in a complex pathophysiological process in the brain. Some in the sporting community believe that headgear (HG) can prevent SRC, and several professional Australian sports organizations, including rugby, football, and soccer clubs, recommend its use.

OBJECTIVE

The purpose of this study is to determine whether HG is effective in lowering the prevalence of SRC in sports.

DATA SOURCES

A systematic search for related studies published between 1985 and 2023 was conducted using the following databases: Cochrane Library, AMED, PubMed, Web of Science, and Physiotherapy Evidence Database (PEDro).

STUDY SELECTION

Only randomized controlled trials (RCTs) that investigated the effectiveness of HG in reducing SRC rate were included.

STUDY DESIGN

Systematic review and meta-analysis of RCTs.

LEVEL OF EVIDENCE

Level 1a.

DATA EXTRACTION

Two researchers independently completed the title and abstract search and performed full-text reviews. A third reviewer was consulted to reach a consensus if any discrepancies were noted. The PEDro scale was used to evaluate the quality of the included RCTs. Data recorded from each study included authors, year of publication, type and number of players, study design, duration of the study, injury rate, compliance (%), sports/level, and exposure hours.

RESULTS

The pooled results of 6311 players and 173,383 exposure hours showed 0% SRC reduction per 1000 hours of exposure in the experimental group compared with the control group, with an injury risk ratio of 1.03 (95% CI, 0.82-1.30; P = 0.79).

CONCLUSION

This systematic review and meta-analysis demonstrates that HG does not prevent SRC among soccer and rugby players, and therefore the findings from this meta-analysis do not currently support the use of HG to prevent SRC in soccer or rugby.

Sport-related concussion attitudes and knowledge in elite English female footballers

BACKGROUND

Sport-related concussions (SRC) are more common and more severe in women's football than men's yet the knowledge and attitudes of SRC in the women's game are not well understood. The objective of this study was to assess the SRC knowledge and attitude in elite female footballers.

METHODS

An online questionnaire was sent to all registered players in the English Football Association Women's Super League (WSL) and Championship. Respondents completed an amended version of the Rosenbaum Concussion Knowledge and Attitudes Survey (RoCKAS). Concussion Knowledge Index (CKI) and Concussion Attitudes Index (CAI) scores were derived for all respondents.

RESULTS

One hundred and twenty-three players completed the survey with 111 fitting the inclusion criteria. The mean CKI score was 20.5 ± 2.3 and the mean CAI score was 63.3 ± 6.3. A weak positive correlation was shown between the CKI and CAI (r = 0.20; p = 0.03). Previous concussion education had a significant impact on increased knowledge (U = 1198; p = 0.04). There was no significant difference in concussion attitudes and knowledge between the WSL and Championship or in those with a previous concussion history and no previous concussion (p > 0.05).

CONCLUSION

Previous SRC education demonstrated an increased knowledge around concussion but a limited impact towards concussion attitudes. It is suggested that concussion education should be mandated across the professional game to enhance player welfare.

The effect of repeated concussions on clinical and neurocognitive symptom severity in different contact sports

INTRODUCTION

The potential consequences of repeated concussions in sport are well documented. However, it remains unclear whether the cumulative impact of sports-related concussions differs between different contact sports. Therefore, the aim of the current study was to investigate the cumulative effects of sports-related concussions on clinical and neurocognitive health in different contact sports.

MATERIALS AND METHODS

In a prospective multicenter study, we examined 507 (74 females) active professional athletes between 18 and 40 years of age from five different contact sports (soccer, handball, American football, basketball, and ice hockey). Data collection involved concussion history, clinical symptom evaluation, neurocognitive assessment, and the collection of other sports-related information. Composite scores were built for clinical symptoms (such as neck pain and balance disturbances) and for neurocognitive symptoms (such as memory and attention impairments).

RESULTS

Athletes having suffered 3+ concussions in the past showed disproportionally higher clinical symptom severity than athletes with less than three concussions across all sports. The level of clinical symptom burden in athletes with 3+ concussions indicated mild impairment. The number of past concussions did not affect neurocognitive performance.

DISCUSSION

Repeated sports-related concussions appear to have a cumulative impact on clinical-but not cognitive-symptom severity. Although clinical symptom burden in athletes with 3+ concussions in the past was not alarmingly high yet in our sample, increased caution should be advised at this point. Despite few exceptions, results are similar for different contact sports, suggesting a similar multidisciplinary concussion management across all types of sport.

A Novel Experimental Approach for the Measurement of Vibration-Induced Changes in the Rheological Properties of Ex Vivo Ovine Brain Tissue

Increased incidence of traumatic brain injury (TBI) imposes a growing need to understand the pathology of brain trauma. A correlation between the incidence of multiple brain traumas and rates of behavioural and cognitive deficiencies has been identified amongst people that experienced multiple TBI events. Mechanically, repetitive TBIs may affect brain tissue in a similar way to cyclic loading. Hence, the potential susceptibility of brain tissue to mechanical fatigue is of interest. Although temporal changes in ovine brain tissue viscoelasticity and biological fatigue of other tissues such as tendons and arteries have been investigated, no methodology currently exists to cyclically load ex vivo brain tissue. A novel rheology-based approach found a consistent, initial stiffening response of the brain tissue before a notable softening when subjected to a subsequential cyclic rotational shear. History dependence of the mechanical properties of brain tissue indicates susceptibility to mechanical fatigue. Results from this investigation increase understanding of the fatigue properties of brain tissue and could be used to strengthen therapy and prevention of TBI, or computational models of repetitive head injuries.

Youth handball concussion prevention strategies: a workshop-based study with experts and end users

Sport-related concussion (SRC) is a serious injury in youth team sports, including handball. While research on the prevention of SRC has made progress over the past 5 years, prevention strategies are lacking in handball. The aim was to explore and develop strategies focusing on information, rules and training that may prevent concussion in youth handball by incorporating knowledge from experts and end users. Using a participatory methodology, experts (physiotherapy, biomechanics: n=3) and end users (players, coaches, referees, coach educators: n=7) contributed their experience and knowledge in a 2-hour online workshop. Participants were given three videos illustrating typical high-risk concussion scenarios from handball games and a youth player's accompanying fictional written scenario. In group discussions inspired by the brainwriting method, participants were asked to provide ideas for possible SRC prevention strategies related to information, rules and/or training. Data were collected on a digital whiteboard and analysed using reflexive thematic analysis. Three themes were derived: (1) 'Coaches' responsibility: raise awareness of the risk of injury and act to promote safe environments'; (2) 'Players' responsibility: safe defence and attack'; and (3) 'Improvement of personal skills'. Experts and end users found information about high-risk situations and SRC symptoms, stricter rules and safe playing strategy training for goalkeepers, attacking and defending players, respectively, may effectively reduce SRC in handball. Information and stricter rules could be delivered through education and dissemination activities, whereas safe playing strategies should be trained at regular handball practice.

Postinjury Outcomes After Non-Sport-Related Concussion: A CARE Consortium Study

CONTEXT

Concussion research has primarily focused on sport-related mechanisms and excluded non-sport-related mechanisms. In adult populations, non-sport-related concussions (non-SRCs) demonstrated worse clinical outcomes compared with sport-related concussions (SRCs); however, investigations of non-SRCs in college-aged patients are limited.

OBJECTIVES

To examine clinical outcomes in collegiate athletes with non-SRCs compared with SRCs and explore sex differences in outcomes among collegiate athletes with non-SRCs.

DESIGN

Prospective cohort study.

SETTING

Clinical setting.

PATIENTS OR OTHER PARTICIPANTS

A total of 3500 athletes were included (n = 555 with non-SRCs, 42.5% female) from colleges or universities and service academies participating in the National Collegiate Athletic Association Department of Defense Concussion Assessment, Research and Education (CARE) Consortium.

MAIN OUTCOME MEASURE(S)

Dichotomous outcomes (yes or no) consisted of immediate reporting, mental status alterations, loss of consciousness, posttraumatic amnesia, retrograde amnesia, motor impairments, delayed symptom presentation, and required hospital transport. Continuous outcomes were symptom severity, days with concussion symptoms, and days lost to injury. Data were collected within 24 to 48 hours of injury and at return to play. Adjusted relative risks (ARRs) compared the likelihood of dichotomous outcomes by mechanism and by sex within patients with non-SRCs. Multivariate negative binomial regressions were used to assess group differences in continuous variables.

RESULTS

Athletes with non-SRCs were less likely to report immediately (ARR = 0.73, 95% CI = 0.65, 0.81) and more likely to report delayed symptom presentation (ARR = 1.17, 95% CI = 1.03, 1.32), loss of consciousness (ARR = 3.15, 95% CI = 2.32, 4.28), retrograde amnesia (ARR = 1.77, 95% CI = 1.22, 2.57), and motor impairment (ARR = 1.45, 95% CI = 1.14, 1.84). Athletes with non-SRCs described greater symptom severity, more symptomatic days, and more days lost to injury (P < .001) compared with those who had SRCs. Within the non-SRC group, female athletes indicated greater symptom severity, more symptomatic days, and more days lost to injury (P < .03) than male athletes.

CONCLUSIONS

Athletes with non-SRCs had worse postinjury outcomes compared with those who had SRCs, and female athletes with non-SRCs had worse recovery metrics than male athletes. Our findings suggest that further investigation of individuals with non-SRCs is needed to improve concussion reporting and management.

Patterns and predictors of concussion symptom presentations in NCAA athletes

Sport-related concussion (SRC) is a complex injury, and SRCs are notably prevalent among National Collegiate Athletic Association (NCAA) athletes. We analysed SRCs and associated exposure data collected within the NCAA Injury Surveillance Program during 2014-2019. A total of 1,709 SRCs were reported with complete symptom profiles during the study period (Women's sports n = 499; Men's sports n = 1,210). Event type and academic class year most commonly predicted specific symptom presentations among athletes in men's sports, while symptom presentation among athletes in women's sports was most commonly predicted by class year and sport classification. We observed 78 and 69 significant pairwise symptom dependencies in men's and women's sports athletes, respectively; odds of longer symptom resolution time were higher with greater counts of symptoms with strongest cross-domain associations. Our findings highlight several contextual predictors of specific symptom presentations and identify parsimonious symptom subsets that may indicate protracted recovery among men's and women's sports athletes.

Mild Traumatic Brain Injury Does Not Significantly Affect Midlife Cognitive Functioning Within the General Population: Findings From a Prospective Longitudinal Birth Cohort Study

OBJECTIVE

To determine whether differences exist in mid-adulthood cognitive functioning in people with and without history of mild traumatic brain injury (mTBI).

SETTING

Community-based study.

PARTICIPANTS

People born between April 1, 1972, and March 31, 1973, recruited into the Dunedin Multidisciplinary Health and Development Longitudinal Study, who completed neuropsychological assessments in mid-adulthood. Participants who had experienced a moderate or severe TBI or mTBI in the past 12 months were excluded.

DESIGN

Longitudinal, prospective, observational study.

MAIN MEASURES

Data were collected on sociodemographic characteristics, medical history, childhood cognition (between 7 and 11 years), and alcohol and substance dependence (from 21 years of age). mTBI history was determined from accident and medical records (from birth to 45 years of age). Participants were classified as having 1 mTBI and more in their lifetime or no mTBI. The Wechsler Adult Intelligence Scale (WAIS-IV) and Trail Making Tests A and B (between 38 and 45 years of age) were used to assess cognitive functioning. T tests and effect sizes were used to identify any differences on cognitive functioning domains between the mTBI and no mTBI groups. Regression models explored the relative contribution of number of mTBIs and age of first mTBI and sociodemographic/lifestyle variables on cognitive functioning.

RESULTS

Of the 885 participants, 518 (58.5%) had experienced at least 1 mTBI over their lifetime, with a mean number of 2.5 mTBIs. The mTBI group had significantly slower processing speed ( P < .01, d = 0.23) in mid-adulthood than the no TBI controls, with a medium effect size. However, the relationship no longer remained significant after controlling for childhood cognition, sociodemographic and lifestyle factors. No significant differences were observed for overall intelligence, verbal comprehension, perceptual reasoning, working memory, attention, or cognitive flexibility. Childhood cognition was not linked to likelihood of sustaining mTBI later in life.

CONCLUSION

mTBI histories in the general population were not associated with lower cognitive functioning in mid-adulthood once sociodemographic and lifestyle factors were taken into account.

National Athletic Trainers' Association Bridge Statement: Management of Sport-Related Concussion

OBJECTIVE

To provide athletic trainers and team physicians with updated recommendations to the 2014 National Athletic Trainers' Association (NATA) concussion position statement regarding concussion management, specifically in the areas of education, assessment, prognostic factors, mental health, return to academics, physical activity, rest, treatment, and return to sport.

BACKGROUND

Athletic trainers have benefited from the 2 previous NATA position statements on concussion management, and although the most recent NATA position statement is a decade old, knowledge gains in the medical literature warrant updating several (but not all) recommendations. Furthermore, in various areas of the body of literature, current evidence now exists to address items not adequately addressed in the 2014 statement, necessitating the new recommendations. This document therefore serves as a bridge from the 2014 position statement to the current state of concussion evidence, recommendations from other organizations, and discrepancies between policy and practice.

RECOMMENDATIONS

These recommendations are intended to update the state of the evidence concerning the management of patients with sport-related concussion, specifically in the areas of education; assessment advances; prognostic recovery indicators; mental health considerations; academic considerations; and exercise, activity, and rehabilitation management strategies.

Acute Fluid Biomarkers for Diagnosis and Prognosis in Children with Mild Traumatic Brain Injury: A Systematic Review

BACKGROUND AND OBJECTIVE

Fluid biomarkers have the potential to improve the accuracy of diagnosis and prognosis in children with mild traumatic brain injury. Our primary objective was to assess the diagnostic and prognostic utility of acute blood and fluid biomarkers in children with mild traumatic brain injury.

METHODS

We performed a systematic review of the published literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Fluid biomarker studies assessing pediatric mild traumatic brain injury diagnosis or prognosis were included if blood or fluids were sampled within 24 h of injury.

RESULTS

Thirty-two studies involving 4743 patients were included comprising 25 diagnostic studies and ten prognostic studies with three studies assessing both diagnosis and prognosis. Sixteen of the 25 diagnostic studies reported the area under the receiver operating characteristic curve (AUC) for predicting abnormal computed tomography scans of the head; S100 calcium binding protein B (S100B, N = 6 studies, AUC range 0.67-1.00), glial fibrillary acidic protein (N = 5, AUC range 0.41-0.85), ubiquitin C-terminal hydrolase (N = 3, AUC 0.59 and 0.83), neuron specific enolase (N = 1, AUC 0.99), total tau (N = 1, AUC 0.65), and interleukin-6 (N = 1, AUC 0.61). In four of the ten prognostic studies, increased acute serum S100B levels, tumor necrosis factor-α, or interleukin-8 were associated with post-concussive symptoms or fatigue from 3 to 12 months post-injury.

CONCLUSIONS

The largest amount of evidence supported the potential use of S100B, glial fibrillary acidic protein, and UCH-L1, but there was mixed accuracy for diagnosis and prognostication for all biomarkers in pediatric mTBI.

What do we know about beach soccer injuries? Systematic video analysis of four consecutive years with 580 match injuries

The aim of the present study was to evaluate the characteristics of match injury in male beach soccer players. Video recordings of all official beach soccer tournaments in which the European national male beach soccer teams participated from 2018 to 2021 were analysed by two sports medicine specialists retrospectively. Regarding each injury, data including the mechanism, location of the injury, whether the injury led to time-loss, and the relationship of the injury to the bicycle kick (BK), etc. were documented. A total of 632 injuries were documented, corresponding to 234.9 injuries/1000 player hours. Video footage was available for 580 injuries. Whilst 79.8% of medical attention injuries occurred due to opponent contact, 19.5% of time-loss injuries occurred due to non-contact, and 12.2% of indirect opponent contact (p < 0.01). The most common location of the BK related injury was the head/neck (68.7%), whereas most common location of the BK unrelated injury was the lower extremity (54.1%) (p < 0.01). The findings demonstrated that beach soccer injury incidence was quite high; the most common injury location was head/neck and head/neck injuries were associated with BK. In light of these results, some rule regulations, particularly those associated with BK, and the use of protective equipment should be considered to prevent these injuries.

The Longitudinal Relationship Between Concussion History, Years of American Football Participation, and Alcohol Use Among Former National Football League Players: an NFL-LONG Study

OBJECTIVE

Investigate the relationships between concussion history and years of football participation (repetitive head impact proxy) with alcohol use across multiple decades in former professional football players.

METHODS

Participants (n = 348; mean age = 49.0 ± 9.4) completed health questionnaires in 2001 and 2019, which included self-reported concussion history and years of participation. Alcohol use frequency and amount per occasion were reported for three timepoints: during professional career, 2001, and 2019. Ordinal logistic regression models were fit to test associations of concussion history and years of participation with alcohol use at each timepoint.

RESULTS

There were no significant associations between either concussion history or years of football participation with alcohol use (frequency and amount per occasion) at any timepoint. Effect estimates for concussion history and years of football participation with alcohol use were generally comparable across timepoints.

CONCLUSIONS

Later life alcohol use by former American football players is not associated with concussion history or years of exposure to football.

The influence of ADHD on recovery from sport concussion among collegiate athletes in the United States: LIMBIC MATARS consortium investigation

OBJECTIVE

The present study aimed to assess the potential influence of a diagnosis of ADHD on concussion recovery among collegiate athletes.

DESIGN

Retrospective and cross-sectional.

METHODS

Data were extracted retrospectively from medical records across LIMBIC MATARS member institutions (n = 11), representing 1,044 concussion cases among collegiate athletes. After exclusions, 406 concussions were included in our analysis (ADHD: n = 38, age = 20.2 ± 1.67 years, 18.4% female; No ADHD: n = 368, age = 19.8 ± 1.39 years, 40.1% female). Mann-Whitney U tests were used to compare days from injury to diagnosis, symptom resolution, and return to sport among athletes with and without ADHD.

RESULTS

No differences were observed for days from concussion until diagnosis (z = -0.33, p = 0.74), until days to symptom resolution (z = -1.30, p = 0.19), or days until return to sport (z = -0.68, p = 0.49); among concussion cases with or without a previously reported diagnosis of ADHD.

CONCLUSION

Our findings further expand the literature that suggests ADHD is not strongly associated with recovery trajectory following sport concussion in collegiate athletes. Future research should extend these findings to be inclusive of additional preexisting health conditions and moderating effects related to medication usage among diverse athlete levels.

Sport-related concussion research agenda beyond medical science: culture, ethics, science, policy

The Concussion in Sport Group guidelines have successfully brought the attention of brain injuries to the global medical and sport research communities, and has significantly impacted brain injury-related practices and rules of international sport. Despite being the global repository of state-of-the-art science, diagnostic tools and guides to clinical practice, the ensuing consensus statements remain the object of ethical and sociocultural criticism. The purpose of this paper is to bring to bear a broad range of multidisciplinary challenges to the processes and products of sport-related concussion movement. We identify lacunae in scientific research and clinical guidance in relation to age, disability, gender and race. We also identify, through multidisciplinary and interdisciplinary analysis, a range of ethical problems resulting from conflicts of interest, processes of attributing expertise in sport-related concussion, unjustifiably narrow methodological control and insufficient athlete engagement in research and policy development. We argue that the sport and exercise medicine community need to augment the existing research and practice foci to understand these problems more holistically and, in turn, provide guidance and recommendations that help sport clinicians better care for brain-injured athletes.

Pituitary dysfunction following mild traumatic brain injury in female athletes

Objective

Pituitary dysfunction following mild traumatic brain injury can have serious physical and psychological consequences, making correct diagnosis and treatment essential. To the best of our knowledge, this study is the first to study the prevalence of pituitary dysfunction following mild traumatic brain injury in an all-female population following detailed endocrinological work-up after screening for pituitary dysfunction in female athletes.

Design

This is a retrospective cohort study.

Methods

Hormone screening blood tests, including serum blood values for thyroid-stimulating hormone, free thyroxin, insulin-like growth factor 1, prolactin, cortisol, follicle-stimulating hormone, luteinizing hormone, estrogen and progesterone, were taken in 133 female athletes. Results were repeatedly outside the reference value in 88 women necessitating further endocrinological evaluation. Two of those were lost to follow-up, and further endocrinological evaluation was performed in 86 participants.

Results

Six women (4.6%, n = 131) were diagnosed with hypopituitarism, four (3.1%) with central hypothyroidism and two with growth hormone deficiency (1.5%). Ten women (7.6%) had hyperprolactinemia, and four (3.1%) of them had prolactinoma. Medical treatment was initiated in 13 (9.9%) women. Significant prognostic factors were not found.

Conclusions

As 12.2% of female athletes with a history of mild traumatic brain injury had pituitary dysfunction (hypopituitarism 4.6%, hyperprolactinemia 7.6%), we conclude that pituitary dysfunction is an important consideration in post-concussion care. Hyperprolactinemia in the absence of prolactinoma may represent pituitary or hypothalamic injury following mild traumatic brain injury.

Significance statement

Mild traumatic brain injury (mTBI) has become a growing public health concern as 50 million people worldwide sustain a traumatic brain injury annually, with mTBI being the most common (70-90%). As studies on mTBI have focused on mostly male populations this study aims to explore pituitary dysfunction (PD) in female athletes following mTBI. To the best of our knowledge, it is the first all-female study on PD following mTBI. The study found that 12.2% of the participating women had PD after mTBI. Six (4.6%) had hypopituitarism and ten (7.6%) had hyperprolactinemia. These findings suggest that PD following mTBI is an important consideration that endocrinologists and other medical staff working with athletes need to be aware of.

Examining the Biopsychosocial Factors Related to Lifetime History of Concussion in Children and Youth

This study investigated the prevalence of lifetime concussions, related psychosocial problems, and post-concussion recovery rates in a clinical sample of children and youth. Participants were 24,186 children and youth (M = 11.9 years, SD = 3.5) who completed an interRAI Child and Youth Mental Health Assessment at mental health agencies across Ontario, Canada. In addition to the expected physiological correlates, results found concussions to be more prevalent in children and youth with attention deficit hyperactivity disorders, anxiety disorders, disruptive behaviour disorders, mood disorders, and those involved in self-harm, harm to others, destructive aggression, and internalizing and externalizing symptoms. The results of this study add to our understanding of children and youth's experiences with concussions. Clinical implications and recommendations are discussed to maximize the effectiveness of evidence-based interventions related to concussion recovery.

Investigating the Association Between Extended Participation in Collision Sports and Fluid Biomarkers Among Masters Athletes

Traumatic brain injuries (TBIs) and concussions are prevalent in collision sports, and there is evidence that levels of exposure to such sports may increase the risk of neurological abnormalities. Elevated levels of fluid-based biomarkers have been observed after concussions or among athletes with a history of participating in collision sports, and certain biomarkers exhibit sensitivity toward neurodegeneration. This study investigated a cohort of 28 male amateur athletes competing in "Masters" competitions for persons >35 years of age. The primary objective of this study was to compare the levels of blood and saliva biomarkers associated with brain injury, inflammation, aging, and neurodegeneration between athletes with an extensive history of collision sport participation (i.e., median = 27 years; interquartile range = 18-44, minimum = 8) and those with no history. Plasma proteins associated with neural damage and neurodegeneration were measured using Simoa® assays, and saliva was analyzed for markers associated with inflammation and telomere length using quantitative real-time polymerase chain reaction. There were no significant differences between collision and non-collision sport athletes for plasma levels of glial fibrillary acidic protein, neurofilament light, ubiquitin C-terminal hydrolase L1, tau, tau phosphorylated at threonine 181, and brain-derived neurotrophic factor. Moreover, salivary levels of genes associated with inflammation and telomere length were similar between groups. There were no significant differences between groups in symptom frequency or severity on the Sport Concussion Assessment Tool-5th Edition. Overall, these findings provide preliminary evidence that biomarkers associated with neural tissue damage, neurodegeneration, and inflammation may not exhibit significant alterations in asymptomatic amateur athletes with an extensive history of amateur collision sport participation.

The knowledge and attitude concerning sport-related concussion among coaches: A survey study

Background

There are no studies investigating the level of knowledge about and attitude towards sports-related concussions (SRC) among sports coaches in Jordan.

Objectives

This study aimed to examine the knowledge about and attitude towards SRC among Jordanian sports coaches.

Method

Our study was based on a cross-sectional survey. An Arabic version of the questionnaire from the Centers for Disease Control and Prevention was used to collect data. The survey identified participants' demographics and knowledge about (0-10 points with higher scores indicating a higher knowledge) and attitude towards (8-40 with lower scores indicating favourable attitudes) SRC. Descriptive statistics and the Kruskal-Wallis test were used to examine knowledge and attitude differences by demographic factors. Spearman's correlation examined the correlation between the total knowledge and attitude scores.

Results

Participants included 193 coaches (62 basketball, 66 martial arts, 30 soccer, and 35 swimming). The median total knowledge and attitude scores were 4 and 30, respectively. The total knowledge score was the highest in martial arts coaches (median = 4) and those with graduate degrees (median = 5). The total attitude score was the lowest among basketball coaches (median = 28) and those who were 40-50 years old (median = 28). No significant correlation between knowledge and attitude scores was observed.

Conclusion

Jordanian coaches have a deficiency in knowledge about SRC and hold attitudes that are not consistent with current practice recommendations.

Clinical implications

Knowledge and attitude about SRC can be improved through education, access to healthcare providers, and adherence to SRC management guidelines.

Longitudinal changes in resting state fMRI brain self-similarity of asymptomatic high school American football athletes

American football has become the focus of numerous studies highlighting a growing concern that cumulative exposure to repetitive, sports-related head acceleration events (HAEs) may have negative consequences for brain health, even in the absence of a diagnosed concussion. In this longitudinal study, brain functional connectivity was analyzed in a cohort of high school American football athletes over a single play season and compared against participants in non-collision high school sports. Football athletes underwent four resting-state functional magnetic resonance imaging sessions: once before (pre-season), twice during (in-season), and once 34-80 days after the contact activities play season ended (post-season). For each imaging session, functional connectomes (FCs) were computed for each athlete and compared across sessions using a metric reflecting the (self) similarity between two FCs. HAEs were monitored during all practices and games throughout the season using head-mounted sensors. Relative to the pre-season scan session, football athletes exhibited decreased FC self-similarity at the later in-season session, with apparent recovery of self-similarity by the time of the post-season session. In addition, both within and post-season self-similarity was correlated with cumulative exposure to head acceleration events. These results suggest that repetitive exposure to HAEs produces alterations in functional brain connectivity and highlight the necessity of collision-free recovery periods for football athletes.

Risk of Two Sport-Related Concussions in the Same Year: Is the Second Concussion Worse?

OBJECTIVES

1) Evaluate the frequency of same-year, repeat concussions; (2) assess predictors of sustaining a repeat concussion; and (3) compare outcomes of athletes with repeat concussions with athletes with single concussion.

DESIGN

A retrospective, case-control study.

SETTING

Regional sports concussion center.

PATIENTS

Adolescents sustaining a sport-related concussions (SRC) from November 2017 to October 2020.

INDEPENDENT VARIABLES

Participants were dichotomized into 2 groups: (1) athletes with a single concussion; and (2) athletes with repeat concussions.

MAIN OUTCOME MEASURES

Between group and within group analyses were completed to look for differences in demographics, personal and family history, concussion history, and recovery metrics between the 2 groups.

RESULTS

Of 834 athletes with an SRC, 56 (6.7%) sustained a repeat concussion and 778 (93.3%) had a single concussion. Between group: Personal history of migraines (19.6% vs 9.5%, χ 2 = 5.795, P = 0.02), family history of migraines (37.5% vs 24.5%, χ 2 = 4.621, P = 0.03), and family history of psychiatric disorders (25% vs 13.1%, χ 2 = 6.224, P = 0.01) were significant predictors of sustaining a repeat concussion. Within group: Among those with a repeat concussion, initial symptom severity was greater (Z = -2.422; P = 0.02) during the repeat concussion and amnesia was more common (χ 2 = 4.775, P = 0.03) after the initial concussion.

CONCLUSIONS

In a single-center study of 834 athletes, 6.7% suffered a same-year, repeat concussion. Risk factors included personal/family migraine history and family psychiatric history. For athletes with repeat concussions, initial symptom score was higher after the second concussion, yet amnesia was more common after the initial concussion.

Head acceleration event exposure and cognitive and functional outcomes: a comparison of multiple football seasons

Athletes in contact sports are exposed to repetitive impacts as an inherent part of sport. There is concern over the accumulative effect; however, much is still unknown regarding their short-term effects. This study investigated impact accumulation and outcomes over three seasons (2015, 2017, 2019) in NCAA Football Bowl Subdivision players. Impacts were recorded using helmet accelerometers, and virtual reality testing (VR) was done across the season. Incidence rates for impacts (total; ≥25 G to <80 G; ≥80 G) all significantly differed by season (p < 0.05). VR scores changed across the seasons, specifically significant decreases in spatial memory (p < 0.05) in 2015, significant changes in balance and spatial memory (p < 0.05) in 2017, and no significant changes in 2019. Linear regressions predicting VR change score by impact incidence rate were nonsignificant. Monitoring exposure to impacts and changes in outcomes is useful; however, results are fluid, and many factors could indirectly have protective effects on athletes.

Associations of prior concussion severity with brain microstructure using mean apparent propagator magnetic resonance imaging

Magnetic resonance imaging (MRI) diffusion studies have shown chronic microstructural tissue abnormalities in athletes with history of concussion, but with inconsistent findings. Concussions with post-traumatic amnesia (PTA) and/or loss of consciousness (LOC) have been connected to greater physiological injury. The novel mean apparent propagator (MAP) MRI is expected to be more sensitive to such tissue injury than the conventional diffusion tensor imaging. This study examined effects of prior concussion severity on microstructure with MAP-MRI. Collegiate-aged athletes (N = 111, 38 females; ≥6 months since most recent concussion, if present) completed semistructured interviews to determine the presence of prior concussion and associated injury characteristics, including PTA and LOC. MAP-MRI metrics (mean non-Gaussian diffusion [NG Mean], return-to-origin probability [RTOP], and mean square displacement [MSD]) were calculated from multi-shell diffusion data, then evaluated for associations with concussion severity through group comparisons in a primary model (athletes with/without prior concussion) and two secondary models (athletes with/without prior concussion with PTA and/or LOC, and athletes with/without prior concussion with LOC only). Bayesian multilevel modeling estimated models in regions of interest (ROI) in white matter and subcortical gray matter, separately. In gray matter, the primary model showed decreased NG Mean and RTOP in the bilateral pallidum and decreased NG Mean in the left putamen with prior concussion. In white matter, lower NG Mean with prior concussion was present in all ROI across all models and was further decreased with LOC. However, only prior concussion with LOC was associated with decreased RTOP and increased MSD across ROI. Exploratory analyses conducted separately in male and female athletes indicate associations in the primary model may differ by sex. Results suggest microstructural measures in gray matter are associated with a general history of concussion, while a severity-dependent association of prior concussion may exist in white matter.

Early intervention treatment in the first 2 weeks following concussion in adults: A systematic review of randomised controlled trials

OBJECTIVE

International guidelines support a repertoire of therapeutic interventions that may assist recovery following concussion. We aimed to systematically review the efficacy of early pharmacological and non-pharmacological interventions initiated within two weeks of injury on symptoms and functional recovery of adults with concussion.

METHODS

We conducted a Systematic Review (SR) of Randomised Controlled Trials (RCTs) without meta-analysis utilising the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search was performed of four databases. Study inclusion criteria were adult participants diagnosed with concussion and commencing active intervention within 14 days of injury.

RESULTS AND CONCLUSIONS

Of 7531 studies identified, 11 were included in the final review. Six studies were rated as high-risk of bias, three with some concerns and two as low-risk of bias. We found no evidence to support specific pharmacotherapeutic management to hasten the natural recovery time-course. Two studies reported significant improvement in selected concussion symptoms following manual therapy (at 48-72 hours post-treatment) or telephone counselling interventions (at 6 months post-injury). No high quality RCTs demonstrate superior effects of early therapeutic interventions on concussion recovery in the first 2 weeks. We advocate future research to examine impacts of health-clinician contact points aligned with symptom-specific interventions.

Association between steroid use and concussions among high school athletes: a cross-sectional analysis of the Youth Risk Behavior Surveillance System

CONTEXT

In 2017, there were almost 2.5 million high school students who experienced a concussion while playing a sport, raising concern for the neurologic problems that they could face. Some of these athletes may seek to gain a competitive advantage in their sport by utilizing substances like steroids. However, steroid use can cause increased aggression and body mass index (BMI), which might lead to heightened risk for concussions. Despite extensive research, we found no previous evidence linking these two factors.

OBJECTIVES

This analysis aims to investigate steroid use trends in high school athletes and to determine whether there is an association between steroid use and concussions in these athletes.

METHODS

We conducted a cross-sectional analysis of the cumulative Youth Risk Behavior Surveillance System (YRBSS). Respondents were added if they participated in sports and answered the steroid and concussion prompts. Demographic variables were assessed including age, grade, BMI, gender, and race/ethnicity.

RESULTS

We found that 3.7 % (n=2991) of high school athletes reported previous steroid use and that 20.7 % (n=2273) reported having sustained a concussion. There was a statistically significant difference in steroid use by race/ethnicity (p<0.001), with the highest rate of use (7.2 %) among American Indian/Alaska Natives (AI/AN). A significantly higher prevalence of steroid use occurred in athletes who were males (4.7 %) than females (2.5 %) and in athletes with a BMI>95 % (5.2 %) compared with those with a BMI between 85 and 95 % (3.9 %) and <85 % (3.5 %) (χ2=135.1, p<0.001 and χ2=16.3, p<0.001, respectively). Further, our results showed that the prevalence of steroid use among high school athletes decreased from 3.4 % in 1999 to 1.9 % in 2019, with the most drastic drop occurring between 2015 and 2019-declining 1.9 %. Whereas 19.6 % of athletes reported a concussion without steroid use, 54.6 % of steroid-utilizing athletes reported having experienced a concussion-a statistically significant finding (adjusted odds ratio [AOR]=4.3; 95 % CI: 3.2-5.9). Finally, compared with White athletes, we found that AI/AN athletes were significantly more likely to have sustained a concussion (AOR=2.3; 95 % CI=1.2-4.3).

CONCLUSIONS

Although our study found decreasing rates of steroid use among high school athletes from 1999 through 2019, our results also show that steroid use is significantly associated with sustaining a concussion. Additionally, the data from YRBSS also demonstrates that AI/AN high school athletes are more likely to utilize steroids and sustain a concussion. Given the long-term consequences of traumatic brain injuries, we recommend that coaches should be aware of potential steroid use among players, and that coaches, athletic trainers, and physicians should all be aware of concussion protocols and remove players from games for evaluation when a concussion is suspected.

Clinical performance of a multiparametric MRI-based post concussive syndrome index

Introduction

Diffusion Tensor Imaging (DTI) has revealed measurable changes in the brains of patients with persistent post-concussive syndrome (PCS). Because of inconsistent results in univariate DTI metrics among patients with mild traumatic brain injury (mTBI), there is currently no single objective and reliable MRI index for clinical decision-making in patients with PCS.

Purpose

This study aimed to evaluate the performance of a newly developed PCS Index (PCSI) derived from machine learning of multiparametric magnetic resonance imaging (MRI) data to classify and differentiate subjects with mTBI and PCS history from those without a history of mTBI.

Materials and methods

Data were retrospectively extracted from 139 patients aged between 18 and 60 years with PCS who underwent MRI examinations at 2 weeks to 1-year post-mTBI, as well as from 336 subjects without a history of head trauma. The performance of the PCS Index was assessed by comparing 69 patients with a clinical diagnosis of PCS with 264 control subjects. The PCSI values for patients with PCS were compared based on the mechanism of injury, time interval from injury to MRI examination, sex, history of prior concussion, loss of consciousness, and reported symptoms.

Results

Injured patients had a mean PCSI value of 0.57, compared to the control group, which had a mean PCSI value of 0.12 (p = 8.42e-23) with accuracy of 88%, sensitivity of 64%, and specificity of 95%, respectively. No statistically significant differences were found in the PCSI values when comparing the mechanism of injury, sex, or loss of consciousness.

Conclusion

The PCSI for individuals aged between 18 and 60 years was able to accurately identify patients with post-concussive injuries from 2 weeks to 1-year post-mTBI and differentiate them from the controls. The results of this study suggest that multiparametric MRI-based PCSI has great potential as an objective clinical tool to support the diagnosis, treatment, and follow-up care of patients with post-concussive syndrome. Further research is required to investigate the replicability of this method using other types of clinical MRI scanners.

Injury Incidence, Outcomes, and Return to Competition Times after Sports-Related Concussions during One Professional Ice Hockey Season: A Prospective Cohort Study

OBJECTIVE

The objective of this study was to analyze the incidence and characteristics of sports-related concussions (SRCs) for a professional ice hockey team during one regular season in the International Central European Hockey League.

BACKGROUND

Repeated concussions are a common cause of long periods of absence in team contact sports, with a wide range of potential short- and long-term consequences for the affected athlete. Questions mainly regarding early diagnosis and ideal follow-up treatment remain unanswered, especially regarding the timing of return to sports (RTS).

METHOD

A prospective data analysis for a professional ice hockey team during a regular season was conducted. Firstly, concussions per 1000 athlete exposure (AE) and average time loss due to SRC were calculated. Secondly, the data from ImPACT Applications were analyzed for those players who were diagnosed with an SRC.

RESULTS

Five SRCs were evaluated during the regular season, which resulted in 1.35 concussions/1000 AEs, a maximum of 17 missed games, and a median of three games per SRC. The average symptom count was 9.6, with the most common symptoms being headache, sensitivity to light, and dizziness.

CONCLUSIONS

SRCs sustained in professional ice hockey are a common in-competition injury, while practices play a subsidiary role. The duration of RTS is highly individual and can be associated with symptoms lasting days to months.

Specialist healthcare services for concussion/mild traumatic brain injury in England: a consensus statement using modified Delphi methodology

OBJECTIVE

To establish a consensus on the structure and process of healthcare services for patients with concussion in England to facilitate better healthcare quality and patient outcome.

DESIGN

This consensus study followed the modified Delphi methodology with five phases: participant identification, item development, two rounds of voting and a meeting to finalise the consensus statements. The predefined threshold for agreement was set at ≥70%.

SETTING

Specialist outpatient services.

PARTICIPANTS

Members of the UK Head Injury Network were invited to participate. The network consists of clinical specialists in head injury practising in emergency medicine, neurology, neuropsychology, neurosurgery, paediatric medicine, rehabilitation medicine and sports and exercise medicine in England.

PRIMARY OUTCOME MEASURE

A consensus statement on the structure and process of specialist outpatient care for patients with concussion in England.

RESULTS

55 items were voted on in the first round. 29 items were removed following the first voting round and 3 items were removed following the second voting round. Items were modified where appropriate. A final 18 statements reached consensus covering 3 main topics in specialist healthcare services for concussion; care pathway to structured follow-up, prognosis and measures of recovery, and provision of outpatient clinics.

CONCLUSIONS

This work presents statements on how the healthcare services for patients with concussion in England could be redesigned to meet their health needs. Future work will seek to implement these into the clinical pathway.

Mixed Martial Arts: Comparing the King-Devick and Sport Concussion Assessment Tool 5 in knockouts, technical knockouts and choke holds

Objective

To compare validity indices of the King-Devick (KD) test and Sport Concussion Assessment Tool 5 (SCAT5) for traumatic events in MMA, and to determine if perfusion events (alterations in consciousness as the result of choke holds) cause similar changes in KD/SCAT5 scores.

Design

A prospective cohort study in MMA fighters who completed KD and SCAT5 assessments before and after a match. Outcomes were categorized as non-event, traumatic event, or perfusion event. KD/SCAT5 changes were compared between all athletes.

Participants

One hundred forty MMA athletes (7 women, 133 men), mean age=27.1 ± 4.9 years.

Intervention

N/A.

Main outcome measures

King-Devick (KD) test and Sport Concussion Assessment Tool 5 (SCAT5).

Results

Among the 140 athletes, 19 sustained traumatic and 15 perfusion events. Testing provided sensitivities/specificities of 21.05%/93.39% (KD) and 77.78%/52.99% (SCAT5) in detecting a traumatic event. KD and SCAT5 Symptom Severity scores differed between athletes with and without traumatic events (P=.041 and .014). KD and SCAT5 Symptoms Score changes were observed between athletes with and without traumatic events (P=.023 and .042). Neither KD nor SCAT5 differed significantly between athletes with and without perfusion events.

Conclusions

The KD test provides high specificity and the SCAT5 demonstrates reasonable sensitivity when detecting a traumatic event. Of the SCAT5, symptoms-related scores may most effectively identify a traumatic event. A traumatic event may cause KD/SCAT5 changes similar to a concussion, while perfusion events did not.

Quest for clarity: investigating concussion-related responsibilities across the New Zealand Rugby Community System

There is a growing concern around concussions in rugby union, at all levels of the game. These concerns highlight the need to better manage and care for players. However, consistency around concussion-related responsibilities of stakeholders across the community rugby system remains challenging. Taking a systems thinking approach, this pragmatic, qualitative descriptive study explored key stakeholder groups within New Zealand's community rugby system's perceptions of their own and others' concussion-related responsibilities. Participants included players from schools and clubs, coaches, parents, team leads and representatives from four provincial unions. A total of 155 participants (67 females and 88 males) were included in the study. Focus groups and individual interviews were conducted. Thematic content analysis was used to analyse data. Thirty concussion-related responsibilities were identified. These responsibilities were contained within four themes: (1) policies and support (responsibilities which influence policy, infrastructure, human or financial resources); (2) rugby culture and general management (responsibilities impacting players' welfare and safety, attitudes and behaviour, including education, injury reporting and communication); (3) individual capabilities (responsibilities demonstrating knowledge and confidence managing concussion, leadership or role/task shifting) and (4) intervention following a suspected concussion (immediate responsibilities as a consequence of a suspected concussion). The need for role clarity was a prominent finding across themes. Additionally, injury management initiatives should prioritise communication between stakeholders and consider task-shifting opportunities for stakeholders with multiple responsibilities. How concussions will realistically be managed in a real-world sports setting and by whom needs to be clearly defined and accepted by each stakeholder group. A 'framework of responsibilities' may act as a starting point for discussion within different individual community rugby contexts on how these responsibilities translate to their context and how these responsibilities can be approached and assigned among available stakeholders.

Risk Factors for Concussion in Under 18, Under 22 and Professional Men's Rugby Union: A Video Analysis of 14,809 Tackles

OBJECTIVE

This study aimed to identify the risk factors for tackle-related concussion observed in matches involving under (U) 18, U 22 and professional men's Rugby Union players through video analysis.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Twenty Rugby Union matches each for high school (U18), university/college (U22) and professional (Elite) were randomly selected from 202 matches in the 2018/2019 season. Both one-on-one and tackles involving multiple tacklers were analyzed for the 60 matches. The 28 categorical and continuous variables (e.g., tackle characteristics and duration before the tackle) were applied as risk factors to a least absolute shrinkage and selection operator (Lasso) regression analysis. To identify high-risk situations, a simulation model with coefficients obtained from the Lasso regression was used. Statistical analysis was conducted according to tackle direction.

RESULTS

A total of 14,809 tackles and 41 concussions involving 1800 players were included in the analyses. The incidence rate of concussions (injuries/1000 tackles) was greater in Elite players (4.0) compared with U18 (1.9) and U22 (2.4) players. The factors most highly associated with concussions were head-in-front tackles (where the tackler's head is placed forward, impeding a ball carrier's forward movements, 11.26/1000 tackles), and were more often observed among U18 players. A simulation model predicted that the highest risk tackle situation in Elite players was a head-in-front, side-on tackle below the hip of the ball carrier (predicted incidence rate 18.07/1000 tackles).

CONCLUSION

The risk factors associated with concussion need to be assessed cautiously. Avoiding head-in-front, side-on tackles to the lower extremities of a ball carrier should be considered to reduce injury risks.

The effects of cytomegalovirus on brain structure following sport-related concussion

The neurotrophic herpes virus cytomegalovirus is a known cause of neuropathology in utero and in immunocompromised populations. Cytomegalovirus is reactivated by stress and inflammation, possibly explaining the emerging evidence linking it to subtle brain changes in the context of more minor disturbances of immune function. Even mild forms of traumatic brain injury, including sport-related concussion, are major physiological stressors that produce neuroinflammation. In theory, concussion could predispose to the reactivation of cytomegalovirus and amplify the effects of physical injury on brain structure. However, to our knowledge this hypothesis remains untested. This study evaluated the effect of cytomegalovirus serostatus on white and grey matter structure in a prospective study of athletes with concussion and matched contact-sport controls. Athletes who sustained concussion (n = 88) completed MRI at 1, 8, 15 and 45 days post-injury; matched uninjured athletes (n = 73) completed similar visits. Cytomegalovirus serostatus was determined by measuring serum IgG antibodies (n = 30 concussed athletes and n = 21 controls were seropositive). Inverse probability of treatment weighting was used to adjust for confounding factors between athletes with and without cytomegalovirus. White matter microstructure was assessed using diffusion kurtosis imaging metrics in regions previously shown to be sensitive to concussion. T1-weighted images were used to quantify mean cortical thickness and total surface area. Concussion-related symptoms, psychological distress, and serum concentration of C-reactive protein at 1 day post-injury were included as exploratory outcomes. Planned contrasts compared the effects of cytomegalovirus seropositivity in athletes with concussion and controls, separately. There was a significant effect of cytomegalovirus on axial and radial kurtosis in athletes with concussion but not controls. Cytomegalovirus positive athletes with concussion showed greater axial (P = 0.007, d = 0.44) and radial (P = 0.010, d = 0.41) kurtosis than cytomegalovirus negative athletes with concussion. Similarly, there was a significant association of cytomegalovirus with cortical thickness in athletes with concussion but not controls. Cytomegalovirus positive athletes with concussion had reduced mean cortical thickness of the right hemisphere (P = 0.009, d = 0.42) compared with cytomegalovirus negative athletes with concussion and showed a similar trend for the left hemisphere (P = 0.036, d = 0.33). There was no significant effect of cytomegalovirus on kurtosis fractional anisotropy, surface area, symptoms and C-reactive protein. The results raise the possibility that cytomegalovirus infection contributes to structural brain abnormalities in the aftermath of concussion perhaps via an amplification of concussion-associated neuroinflammation. More work is needed to identify the biological pathways underlying this process and to clarify the clinical relevance of this putative viral effect.

Examining the occurrence and outcomes of concussion and mTBI in mixed martial arts athletes: a systematic review

INTRODUCTION

Mixed martial arts (MMA) is a sport growing in popularity around the world. However, many individuals participate in the sport with little understanding of the potential short- and long-term consequences of injuries sustained while participating. Specifically, individuals are placed at a high risk of minor traumatic brain injury (mTBI) and concussive episodes as a result of head injuries incurred during training and competition.

AIMS

The current review aimed to examine the literature surrounding the occurrence and outcomes of mTBI in MMA athletes to gain a better understanding of these consequences.

METHODS

Twenty-five studies were identified within the current review, of which 14 examined occurrence of mTBI within the sport setting, and elevenidentified outcomes of injury.

RESULTS

Overall, studies found that MMA athletes experienced mTBI and concussion to a greater extent than athletes in other sports. Deficits in memory, reaction time and processing speed were identified following occurrence of mTBI; however, several gaps in outcome measurement were identified within the current literature, including a lack of focus on speech and language outcomes.

CONCLUSION

Future research should examine a wider variety of outcomes to provide a clearer understanding of the consequences of participating in the sport.

Incidence of concussion in men's Super League, Championship, and Academy rugby league matches between 2016 and 2022

OBJECTIVES

To quantify the incidence of concussion and compare between playing levels in male rugby league.

DESIGN

Retrospective cohort.

METHODS

Between 2016 and 2022, medically diagnosed concussions in Super League, Championship, and Academy competitions were reported to the Rugby Football League via club medical staff. Anonymised data were analysed using generalised linear mixed-effects models by season, month, and between competitions.

RESULTS

Overall, 1403 concussions were identified from 104,209 player-match hours. Concussion incidence for Super League, Championship, and Academy was 15.5, 10.5, and 14.3 per 1000 player-match hours, respectively. Championship concussion incidence was significantly lower than the Super League (p < 0.001) and Academy (p < 0.001). No significant differences were identified between years for Super League (range: 13.3 to 18.8 per 1000 player-match hours) and Championship (range: 8.4 to 12.1 per 1000 player-match hours). In Academy (range: 9.6 to 20.5 per 1000 player-match hours), concussion incidence was significantly greater in 2021 compared to earlier years (2016, p = 0.01 and 2017, p = 0.03). No significant differences were identified between months for any competition.

CONCLUSIONS

The incidence of concussion is greater in Super League and Academy compared to the Championship. Academy concussion incidence has increased over time. Different factors between and within competitions, such as changes to medical standards and knowledge, could have influenced the identification and diagnosis of concussion.

National Collegiate Athletic Association athletic trainers' response to the Arrington settlement: management, compliance, and practice patterns

The primary purpose of this study was to assess Athletic Trainers' (ATs) report of NCAA member institution compliance with the Arrington settlement, the concussion lawsuit vs. the NCAA, and to elucidate compliance predictors. A secondary purpose was to provide a contemporary concussion management clinical practice pattern description among NCAA collegiate athletic trainers. Head Athletic Trainers from NCAA Division I, II, and III completed an electronic questionnaire in August 2020 regarding their institution's response to the Arrington Settlement and their current concussion management clinical practice patterns. The 37-item questionnaire included AT and institution demographics, current concussion management policies, and response to the Arrington settlement with a specific focus on the five settlement requirements. An overall compliance score on the five requirements, compliance on the individual requirements, and concussion management practices are reported with descriptives. Regression was used to identify specific predictors of both overall and individual settlement requirements. An ANOVA compared compliance by NCAA division level. Being pressured to be non-compliant was assessed between sexes by a chi-square. There were 223 respondents (21.8%), and overall compliance was high (4.1 ± 0.7) with the five required Arrington Settlement components. Settlement requirement 1, pre-season baseline testing, and requirement 5, presence of trained personnel at all contact sport practices, had the lowest compliance rates at 44.8% and 73.3%, respectively. The number of sports the institution offered was the only significant predictor of each requirement. There was no difference in compliance between NCAA divisions. Although the overall rate of being non-compliant pressure was low (13.8%), females were 3.28x more likely report being pressured than males. NCAA institutions are generally compliant with the Arrington settlement; however, lack of clarity in the requirements, particularly requirement 1, raises potential concerns. Concussion management practices continue to incorporate multifaceted approaches and are largely consistent with current best practices.

Prior exposure to concussions in patients with isolated REM sleep behavior disorder

OBJECTIVE

Traumatic brain injury is associated with the late development of neurodegenerative diseases such as the synucleinopathies. Isolated REM sleep behavior disorder (IRBD) constitutes an early manifestation of the synucleinopathies. We assessed whether lifetime history of concussive episodes is common in IRBD and examined its characteristics and clinical significance.

METHODS

Prior exposure to concussions was evaluated by interviewing polysomnographically-confirmed IRBD patients and controls without IRBD, and by the BRAIN-Q questionnaire.

RESULTS

We recruited 199 IRBD patients aged 73.2 ± 7.7 years and 168 age and sex matched controls. Previous history of concussion was more common in patients than in controls (21.1% versus 10.1%, p = 0.004). In patients, concussions occurred at the age of 24.7 ± 20.6 years. The interval between concussion and IRBD diagnosis was 43.0 ± 19.0 years. There were no differences between patients and controls in the causes of concussions (e.g., traffic accidents, sport practice), and number of events resulting in skull fractures, urgent medical assistance, and hospitalization. After a follow-up of 5.7 ± 4.7 years from IRBD diagnosis, 21.1% patients developed an overt synucleinopathy with an interval of 49.3 ± 24.2 years between concussion and synucleinopathy diagnosis. The risk to develop a synucleinopathy was similar between patients with and without concussions (p = 0.57).

CONCLUSIONS

Previous history of concussion is common in IRBD. Our observations may suggest that in individuals with increased susceptibility, early-life concussions may trigger a slow neurodegenerative process leading four decades later to IRBD. This study highlights the need for head injury prevention, particularly in early life.

DNA Methylation-Mediated Mfn2 Gene Regulation in the Brain: A Role in Brain Trauma-Induced Mitochondrial Dysfunction and Memory Deficits

Repeated mild traumatic brain injuries (rMTBI) affect mitochondrial homeostasis in the brain. However, mechanisms of long-lasting neurobehavioral effects of rMTBI are largely unknown. Mitofusin 2 (Mfn2) is a critical component of tethering complexes in mitochondria-associated membranes (MAMs) and thereby plays a pivotal role in mitochondrial functions. Herein, we investigated the implications of DNA methylation in the Mfn2 gene regulation, and its consequences on mitochondrial dysfunction in the hippocampus after rMTBI. rMTBI dramatically reduced the mitochondrial mass, which was concomitant with decrease in Mfn2 mRNA and protein levels. DNA hypermethylation at the Mfn2 gene promoter was observed post 30 days of rMTBI. The treatment of 5-Azacytidine, a pan DNA methyltransferase inhibitor, normalized DNA methylation levels at Mfn2 promoter, which further resulted into restoration of Mfn2 function. The normalization of Mfn2 function was well correlated with recovery in memory deficits in rMTBI-exposed rats. Since, glutamate excitotoxicity serves as a primary insult after TBI, we employed in vitro model of glutamate excitotoxicity in human neuronal cell line SH-SY5Y to investigate the causal epigenetic mechanisms of Mfn2 gene regulation. The glutamate excitotoxicity reduced Mfn2 levels via DNA hypermethylation at Mfn2 promoter. Loss of Mfn2 caused significant surge in cellular and mitochondrial ROS levels with lowered mitochondrial membrane potential in cultured SH-SY5Y cells. Like rMTBI, these consequences of glutamate excitotoxicity were also prevented by 5-AzaC pre-treatment. Therefore, DNA methylation serves as a vital epigenetic mechanism involved in Mfn2 expression in the brain; and this Mfn2 gene regulation may play a pivotal role in rMTBI-induced persistent cognitive deficits. Closed head weight drop injury method was employed to induce repeated mild traumatic brain (rMTBI) in jury in adult, male Wistar rats. rMTBI causes hyper DNA methylation at the Mfn2 promoter and lowers the Mfn2 expression triggering mitochondrial dysfunction. However, the treatment of 5-azacytidine normalizes DNA methylation at the Mfn2 promoter and restores mitochondrial function.