Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies

Associations of Collegiate Football Career and Incident Concussion with Players' Health: A Longitudinal Study from the CARE Consortium

BACKGROUND

The influence of repetitive head impacts on collegiate football players remains unclear as prior research is often limited to small samples or short-term studies focused on single seasons.

OBJECTIVE

Our objective was to determine the associations between collegiate football career or incident concussion and changes in neurocognitive function, postural stability, and physical and psychological health.

METHODS

In total, 574 football players enrolled in the Grand Alliance Concussion Assessment, Research and Education (CARE) Consortium (median age 18.0 years [interquartile range 18.0-19.0], 52% white race, 26% with incident concussion) completed baseline and exit evaluations (i.e., beginning and end of collegiate career) consisting of neurocognitive, postural stability, and physical/psychological health assessments, specifically, Immediate Post-Concussion Assessment and Cognitive Testing, Standardized Assessment of Concussion, Balance Error Scoring System, Sport Concussion Assessment Tool-5 (SCAT-5) Symptom checklist, and the Brief Symptom Inventory-18. Adjusted linear regression models incorporating inverse probability of attrition weighting were used to compare changes in scores between baseline and exit evaluations overall and by incident concussion status.

RESULTS

Overall, athletes had small improvements in neurocognitive functioning and postural stability over time but had small increases in symptom severity. Both the incident concussion and no incident concussion groups improved similarly on neurocognitive and postural stability measures (all p > 0.05 for difference in change over time between incident concussion groups). Individuals with incident concussion reported fewer symptoms and lower symptom severity over time than did those without incident concussion (SCAT symptom count difference - 1.22; 95% confidence interval [CI] - 1.89 to - 0.54; SCAT symptom severity difference: - 2.46; 95% CI - 4.06 to - 0.86; Brief Symptom Inventory-18 somatization difference: - 0.55; 95% CI - 0.93 to - 0.17).

CONCLUSIONS

Overall, collegiate football players demonstrated small, non-clinically meaningful improvements in neurocognitive function and postural stability. Moreover, athletes who experienced a concussion reported slight improvements in physical/psychological health symptoms over their collegiate careers.

Contact-events and associated head acceleration events in semi-elite women's rugby union: A competition-wide instrumented mouthguard study

This study aimed to quantify contact-events and associated head acceleration event (HAE) probabilities in semi-elite women's rugby union. Instrumented mouthguards (iMGs) were worn by players competing in the 2023 Farah Palmer Cup season (13 teams, 217 players) during 441 player-matches. Maximum peak linear acceleration (PLA) and peak angular acceleration (PAA) per-event were used as estimates of in vivo HAE (HAEmax), linked to video analysis-derived contact-events and analysed using mixed-effects regression. Back-rows had the highest number of contact-events per full-match (44.1 [41.2 to 47.1]). No differences were apparent between front-five and centres, or between half-backs and outside-backs. The probability of higher HAEmax occurring was greatest in ball-carries, followed by tackles, defensive rucks and attacking rucks. Probability profiles were similar between positions but the difference in contact-events for each position influenced HAEmax exposure. Overall, most HAEmax were relatively low. For example, the probability of a back-row experiencing a PLA HAEmax ≥25g was 0.045 (0.037-0.054) for ball carries (1 in every 22 carries), translating to 1 in every 2.3 full games. This study presents the first in-depth analysis of contact-events and associated HAEmax in semi-elite women's rugby union. The HAEmax profiles during contact-events can help inform both policy and research into injury mitigation strategies.

Investigating the Association of Concussion and Contact Sport Exposure History With Brain Microstructure Using Quantitative Susceptibility Mapping

A growing body of evidence suggests that repeated concussions and exposure to repetitive head impacts may be associated with subtle abnormalities in neurological health. Prior studies have demonstrated associations of prior concussion and repetitive head impacts with the brain's microstructure, typically using diffusion magnetic resonance imaging, though the direction of these relationships has varied across groups. Quantitative susceptibility mapping is a quantitative extension of susceptibility weighted imaging that is sensitive to pathophysiology associated with neurotrauma and thus represents an alternative method to characterize the effects of concussion and repetitive head impact exposure on brain microstructure. The goal of this work was to characterize the association of prior concussion and years of contact sport exposure (a proxy of repetitive head impacts) with magnetic susceptibility in a cohort of otherwise healthy male and female collegiate-aged athletes. We hypothesized that concussion and contact sport exposure would be independently associated with lower susceptibility in white matter regions. Higher general symptom severity and psychological symptoms were observed in athletes with a greater history of concussion, but not years of contact sport exposure. No associations between concussion or years of exposure with cognitive performance were observed. Voxel-wise analyses found that individuals with more prior concussions also had lower magnetic susceptibility in two predominantly white matter clusters including the superior longitudinal fasciculi and forceps major. No associations of susceptibility and contact sport exposure were observed. Finally, lower susceptibility in the identified regions was associated with worse psychological symptoms, worse general symptoms, and worse performance on a composite measure of fluid cognition tasks. Current results suggest that more prior concussions in otherwise healthy collegiate-aged athletes are associated with decreases in susceptibility that are in turn associated with elevated symptom reporting and poorer cognitive performance.

Collegiate Participation in Repetitive Head Impact Sports Does Not Adversely Affect Gait Dual Task Cost

OBJECTIVES

The purpose of this study was to assess gait related dual task cost (DTC) changes over the course of a collegiate athletic career in both repetitive head impact (RHI) exposed and non-RHI exposed athletes.

SETTING

University Research Laboratory.

PARTICIPANTS

We recruited 47 NCAA intercollegiate athletes and grouped by RHI exposed (N = 27) and non-RHI (N = 20) sports.

DESIGN

Participants completed 5 trials of single task (ST) and 5 trials of dual task (DT) gait with a working memory cognitive challenge both prior to their collegiate athletic careers (pre) and then again after they completed their collegiate athletic careers (post) (mean 1173 ± 341 days between tests) in this prospective longitudinal design. To assess for changes over the course of a career, separate 2 (group: RHI, non-RHI) × 2 (time: pre, post) mixed design ANOVA were performed for each dependent variable of interest (DTC gait velocity and DTC step length) and the model was adjusted for concussion history at the time of test and sex.

MAIN MEASURES

Gait velocity and step length DTC.

RESULTS

There were no significant group by time interactions for DTC gait velocity (F = 0.517, P = .476, η2 = 0.012) or DTC step length ((F = 0.206, P = .652, η2 = 0.005).

CONCLUSIONS

The primary finding of this study indicated no difference between RHI exposed and non-RHI exposed athletes gait DTC performance between the beginning and conclusion of their collegiate athletic careers. While the long-term effects of RHI remain to be fully determined, these results suggest that RHI may not adversely affect ST or DT gait performance when the individual is young.

Concussions Are Associated With Increases in Blood Pressure and Cardiovascular Risk in American-Style Football Athletes

BACKGROUND

Concussions sustained during American-style football (ASF) participation are common. Whether concussions are associated with cardiovascular risk is unknown.

OBJECTIVES

The authors sought to determine whether concussions sustained during collegiate ASF participation lead to increases in systolic blood pressure (SBP) and acquired maladaptive cardiovascular phenotypes.

METHODS

In a longitudinal and case-controlled analysis, ASF athletes at 2 National Collegiate Athletic Association Division-I programs were followed for up to 2 years with cardiovascular assessments including BP, echocardiography, and vascular applanation tonometry. ASF athletes who sustained clinically diagnosed concussions were compared to weight and player position-matched controls without concussions.

RESULTS

Thirty-nine ASF athletes who sustained concussions (preconcussion baseline: [SBP] 129.6 ± 13.6 mm Hg) and 39 weight and player position-matched controls (preconcussion baseline: [SBP] 131.6 ± 13.1 mm Hg) were followed for 1 season postconcussion; 14 of these pairs were followed through 2 seasons. After 1 season, increased pulse wave velocity (PWV) (case Δ = 0.4 [0.2] m/s, P = 0.036; control Δ = -0.1 [0.1] m/s, P = 0.38) was observed among cases. Among the case and control pairs followed over 2 seasons, increased SBP (case Δ = 10.1 [3.6] mm Hg, P < 0.01; control Δ = 0.1 [3.2] mm Hg, P = 0.97) and diastolic blood pressure (case Δ = 8.2 [2.9] mm Hg, P < 0.01; control Δ = -4.1 [4.0] mm Hg, P = 0.30) and decreased É (case Δ = -2.8 [0.8] cm/s, P = 0.001; control Δ = -1.0 [0.8] cm/s, P = 0.21) were observed among cases. Over 1 season, concussions were associated with higher PWV (β = 0.33 [95% CI: 0.09-0.56], P = 0.007). Among athletes followed over 2 seasons, concussions were associated with higher PWV (β = 0.42 [95% CI: 0.05-0.78], P = 0.03), diastolic blood pressure (β = 5.89 [95% CI: 1.23-10.54], P = 0.01), LV mass index (β = 11.01 [95% CI: 6.13-15.90], P < 0.001), and lower É (β = -2.11 [95% CI: -3.27 to -0.95], P < 0.001).

CONCLUSIONS

Concussions sustained during collegiate ASF participation are independently associated with markers of cardiovascular risk and acquired maladaptive cardiovascular phenotypes. Clinical ASF concussion management strategies inclusive of careful BP surveillance may lead to early identification of hypertension.

What Is in a Name? Depression and Anxiety Symptoms in Collegiate Athletes With and Without a History of Concussion

CONTEXT

Athletes with a history of concussion (CON) have been demonstrated to have heightened levels of anxiety and depression that may continue well beyond the resolution of concussion symptoms. The global events of 2020 resulted in elevated levels of anxiety and depression in the general population, which may have unequally presented in collegiate athletes with (CON) than those without a history of concussion (NoCON). Using a deception design, our survey-based study compared levels of anxiety and depression in CON and NoCON collegiate athletes in response to the pandemic and social injustices. We hypothesized that the CON group would have significantly elevated anxiety and depression as compared to the NoCON group in response to events of 2020.

DESIGN AND METHODS

Collegiate athletes (N = 106) during the academic 2020-2021 academic year were divided into CON and NoCON groups based on their preinjury (baseline) concussion assessment. Participants completed the Social Readjustment Rating Scale (SSRS), Center for Epidemiologic Studies Depression Scale (CES-D), and Generalized Anxiety Disorder Scale-7 (GAD-7) via an electronic survey pertaining to the events of 2020. The term "concussion" was not used in any study materials which was the basis for our deception-based design. An analysis of covariance was used to compare group CES-D and GAD-7 outcome scores while controlling for the SSRS outcome score.

RESULTS

Our survey response rate was 14.2% (48/337 [77.1% female]) and 10.1% (58/580 [67.2% female]), for the NoCON and CON groups, respectively. The NoCON group had significantly (F1 = 5.82, P = .018, ηp2=.06) higher anxiety (8.3 [5.89]) as compared to the CON group (5.5 [2.85]). The NoCON group also had significantly (F1 = 13.7, P < .001, ηp2=.12) higher levels of depression (21.0 [12.52]) as compared to the CON group (16.07 [9.10]).

DISCUSSION

Our deception-based study revealed NoCON participants had elevated and clinically relevant mood states as compared to CON participants in response to the events of 2020.

The Relationship Between Concussion and Combat History and Mental Health and Suicide Ideation Among United States Military Veterans-A Pilot Study

Background/Objectives: Suicides among U.S. military veterans are alarmingly high, driven by factors such as mental health issues, combat exposure, and history of mild traumatic brain injury (mTBI)/concussion. This study aims to examine the relationship between concussion history, combat experience, and their effects on mental health issues and suicide ideation among military veterans. Additionally, this study investigates the impact of post-traumatic stress disorder (PTSD) on these variables. Methods: A total of 78 veterans (62 males, 16 females) participated in this study. Participants completed a demographic survey and the Global Well-being Index (GWI) to assess concussion history and residual symptoms. A licensed social worker interviewed the veterans using the 9-Item Patient Health Questionnaire (PHQ-9) for depression, the Generalized Anxiety Disorder survey (7 Items) (GAD-7) for anxiety, and the Columbia-Suicide Severity Rating Scale (C-SSRS) for suicide ideation. A 2 × 2 cross-tabulation analysis examined the relationships between concussion history, combat experience, and outcomes of anxiety, depression, and suicide ideation. PTSD was also assessed as both a predictor and an outcome. Statistical analyses yielded odds ratios (OR) with 95% confidence intervals (CI), Chi-square, and Cramer's V (V) correlations along with associated p-values. Results: The combination of concussion history and combat experience strongly predicted either anxiety, depression, or suicide ideation (OR = 7.97, 95% CI: 1.70, 37.44; V = 0.334, (p = 0.003)), more than either factor alone. Combat experience was the strongest predictor of PTSD (OR = 11.12, 95% CI: 3.30, 37.47; V = 0.485, p ≤ 0.001), both individually and when combined with concussion history. PTSD strongly influenced mental health issues and suicide ideation (OR = 8.16, 95% CI: 1.74, 38.25; V = 0.339, p = 0.003). Stratification by PTSD status (positive or negative) affected the relationships between independent and dependent variables. Small cell counts resulted in a wide 95% CI for some ORs, though some statistically significant Fisher's Exact Test results were observed. Credibility analysis using the critical prior interval (CPI) metric confirmed the intrinsic credibility of the results. Conclusions: This study provides insights into the relationships between concussion history, combat experience, and their impacts on mental health issues and suicide ideation among military veterans.

Concussion and depressive symptoms in high school students: impact of physical activity and substance use

OBJECTIVE

To investigate the association between concussion history and depressive symptoms after adjusting for physical activity, substance use, and illicit drug use.

METHODS

We analysed data from the Adolescent Behaviour and Experiences Survey, a nationally representative survey of adolescents in the USA. Our independent variables were history of concussion in the 12 months preceding survey completion; self-reported weekly physical activity (days per week with >60 min of physical activity, 0-7 scale); substance use over the past 30 days (yes vs no) and illicit drug use throughout lifetime (yes vs no). Our dependent variable was participant-reported sadness/hopelessness over the past 12 months (yes vs no).

RESULTS

Among 7499 adolescents (9th-12th grade, 50.4% female), reporting one or more concussions over the past year was not associated with the odds of depressive symptoms (OR: 1.13, 95% CI: 0.93 to 1.37, p=0.21). Each additional day of physical activity per week was associated with a lower odds of depressive symptoms (OR: 0.91; 95% CI: 0.89 to 0.94; p<0.0001). Illicit drug use (OR ever vs never: 2.48; 95% CI: 1.96 to 3.13; p<0.0001) and substance use (OR yes vs no: 2.77; 95% CI: 2.34 to 3.29; p<0.001) were associated with a higher odds of depressive symptoms.

CONCLUSIONS

Adjusting for physical activity, substance use and illicit drug use, concussion was not significantly associated with depressive symptoms. This novel discovery informs clinicians as they counsel adolescents with concussion; future research should examine physical activity and avoidance of substance/illicit drug use as postinjury recommendations in an effort to lower the risk of depressive symptoms.

Epidemiological Principles in Claims of Causality: An Enquiry into Repetitive Head Impacts (RHI) and Chronic Traumatic Encephalopathy (CTE)

Determining whether repetitive head impacts (RHI) cause the development of chronic traumatic encephalopathy (CTE)-neuropathological change (NC) and whether pathological changes cause clinical syndromes are topics of considerable interest to the global sports medicine community. In 2022, an article was published that used the Bradford Hill criteria to evaluate the claim that RHI cause CTE. The publication garnered international media attention and has since been promoted as definitive proof that causality has been established. Our counterpoint presents an appraisal of the published article in terms of the claims made and the scientific literature used in developing those claims. We conclude that the evidence provided does not justify the causal claims. We discuss how causes are conceptualised in modern epidemiology and highlight shortcomings in the current definitions and measurement of exposures (RHI) and outcomes (CTE). We address the Bradford Hill arguments that are used as evidence in the original review and conclude that assertions of causality having been established are premature. Members of the scientific community must be cautious of making causal claims until the proposed exposures and outcomes are well defined and consistently measured, and findings from appropriately designed studies have been published. Evaluating and reflecting on the quality of research is a crucial step in providing accurate evidence-based information to the public.

Head Injury and Amyotrophic Lateral Sclerosis: Population-Based Study from the National ALS Registry

Background/Objectives: To examine if head injury (HI) is associated with age at ALS diagnosis in the United States. Methods: In this cross-sectional populationf-based analysis, we identified patients with ALS who were registered from 2015 to 2023 who completed the Registry's head trauma survey module. The association between HI and age at ALS diagnosis was assessed using multivariate analysis. Results: Of the 3424 respondents, 56.6% had experienced a HI. The adjusted odds ratio (aOR) for an ALS diagnosis before age 60 years for patients with a HI was 1.24 (95% CI, 1.07-1.45). One or two HIs had an aOR of 1.15 (95% CI, 0.97-1.36), and five or more HIs had an aOR of 1.58 (95% CI, 1.19-2.09). HI before age 18 years yielded an aOR of 2.03 (95% CI, 1.53-2.70) as well as HI between the ages of 18 and 30 years (aOR = 1.48, 95% CI: 1.06-2.06)). When narrowing the analysis to patients with HI before age 18 compared with patients with no HI, we found an association with HI that led to an emergency department or hospital visit (aOR = 1.50 (95% CI: 1.21-1.86)). Conclusions: In this cross-sectional analysis of ALS patients, HIs occurring in childhood and early adulthood and the number of HIs increased the odds of being diagnosed before age 60 years. These results suggest that HI continues to be a risk factor for ALS and could be associated with a younger age of diagnosis.

Can a novel computer vision-based framework detect head-on-head impacts during a rugby league tackle?

BACKGROUND

Head-on-head impacts are a risk factor for concussion, which is a concern for sports. Computer vision frameworks may provide an automated process to identify head-on-head impacts, although this has not been applied or evaluated in rugby.

METHODS

This study developed and evaluated a novel computer vision framework to automatically classify head-on-head and non-head-on-head impacts. Tackle events from professional rugby league matches were coded as either head-on-head or non-head-on-head impacts. These included non-televised standard-definition and televised high-definition video clips to train (n=341) and test (n=670) the framework. A computer vision framework consisting of two deep learning networks, an object detection algorithm and three-dimensional Convolutional Neural Networks, was employed and compared with the analyst-coded criterion. Sensitivity, specificity and positive predictive value were reported.

RESULTS

The overall performance evaluation of the framework to classify head-on-head impacts against manual coding had a sensitivity, specificity and positive predictive value (95% CIs) of 68% (58% to 78%), 84% (78% to 88%) and 0.61 (0.54 to 0.69) in standard-definition clips, and 65% (55% to 75%), 84% (79% to 89%) and 0.61 (0.53 to 0.68) in high-definition clips.

CONCLUSION

The study introduces a novel computer vision framework for head-on-head impact detection. Governing bodies may also use the framework in real time, or for retrospective analysis of historical videos, to establish head-on-head rates and evaluate prevention strategies. Future work should explore the application of the framework to other head-contact mechanisms and also the utility in real time to identify potential events for clinical assessment.

Comparing Time to Recovery Between Initial and Repeat Concussion in Athletes

OBJECTIVE

Compare time to recovery between initial and repeat concussions.

DESIGN

Retrospective review of electronic medical record.

SETTING

An interdisciplinary concussion clinic.

PATIENTS

Fifty patients (14.4 years old [±2.5]; 24 [48%] female) who sustained >1 concussion between 2016 and 2020 and were evaluated within 30 days of their concussion.

INTERVENTION

Injuries were divided into first, second, and/or last concussions.

MAIN OUTCOME MEASURES

The primary outcome was time to recovery, as defined by clearance for return to sport. This was compared between first versus second concussion (primary analysis) and first versus last concussion (secondary analysis) using Cox regression. Multivariable models accounted for time from concussion to initial clinic visit and Sport Concussion Assessment Tool symptom severity score at initial encounter. Sensitivity analyses explored potential influences of initial encounter timing and interval between concussions.

RESULTS

Time to recovery did not differ between initial and repeat concussion in univariate or multivariable models (HR = 1.02, 95% CI, 0.65-1.62, P = 0.92; HR = 1.01, 95% CI, 0.64-1.62, P = 0.91 for multivariable models comparing first (ref) versus second and first (ref) versus last concussion, respectively). Similar results were obtained in sensitivity analyses stratifying by time to initial visit (≤7 days vs >7 days) or time between injuries (≤1 year vs >1 year).

CONCLUSIONS

There were no differences in time to recovery between initial and repeat concussions sustained by the same athlete. A nonsignificant trend of shorter recovery after repeat concussions was observed for patients presenting within 1 week of injury and when repeat injuries occurred within 1 year.

Relationship between self-reported concussion history, cognition, and mood among former collegiate athletes

Objective: This study explored the relationship between concussion history and cognition/mood in former collegiate athletes in middle-to-later adulthood. Method: 407 former collegiate athletes aged 50+ (M = 61.4; 62.7% male) participated in the College Level Aging AThlete Study (CLEAATS) and completed the Cognitive Function Instrument (CFI), 40-item Telephone Interview for Cognitive Status (TICS-40), PHQ-8, GAD-7, and self-report questionnaires, including concussion history. Kruskal-Wallis tests assessed for differences among groups based on concussion history (0, 1-2, 3-4, 5+ concussions). Hierarchical multiple regressions including demographic factors as covariates examined relationships between concussion history, emotional symptoms, and subjective/objective cognition. Results: Participants with 5+ concussions reported significantly greater subjective cognitive concerns and depressive symptoms than other concussion groups, but no differences were found in objective cognition. Hierarchical regression revealed concussion history and emotional symptoms explained 29% and 15% of the variance in subjective and objective cognition, respectively. The number of concussions accounted for unique variance in subjective cognition but was not significantly associated when mood symptoms were added to the model. Neither diagnosed concussions nor emotional symptoms were associated with objective cognition. Conclusions: When accounting for concussion history, those with 5+ concussions reported greater subjective cognitive symptoms than those with 0-2 concussions, and greater depressive symptoms than those with 0 concussions. Concussion history was not significantly related to subjective cognition when compared to mood, and concussion history and mood symptoms were not associated with objective cognition. Results highlight the importance of considering mood symptoms when evaluating the relationship between concussion history and cognition in former athletes.

After the buzzer sounds: Adults unveil the consequences of concussions sustained during adolescence

Concussions are commonly occurring injuries in sport. The short-term impacts of concussions, including symptoms and recovery trajectories, often are the focus of concussion research. However, limited studies have explored the long-term consequences of concussions, especially in adolescents. The purpose of this study was to explore adults' experiences with concussions sustained during their adolescence (5-15 years prior). This qualitative study was guided by an interpretivist philosophy. Twenty young adults (11 men, 9 women, median age 26) who had sustained at least one sport-related concussion during their adolescence participated in a one-on-one semi-structured interview. We aimed to explore their experiences with their concussion at the time of injury and any consequences they experienced as a result of their concussion. We organized participants' concussion experiences into six main themes: (1) Concussion diagnosis and experiences with health care providers; (2) Emotional symptoms following concussion; (3) Concussion recovery; (4) Change in sport participation and engagement; (5) Concern about the potential long-term consequences; and (6) Impact on social relationships. We used the Biopsychosocial Model of Sport Injury Rehabilitation to organize the themes. Future research should explore how acute multi-disciplinary support could reduce the negative long-term consequences of concussion in adolescents.

MR elastography-based detection of impaired skull-brain mechanical decoupling performance in response to repetitive head impacts

OBJECTIVE

To evaluate MR elastography (MRE)-assessed biomarkers for detecting changes in skull-brain mechanical decoupling performance induced by repetitive head impacts (RHIs).

METHODS

This prospective single-center study enrolled 80 asymptomatic participants (2017-2023) divided into three groups: no exposure (RHI(-)), low-impact (low RHI(+)), and high-impact (high RHI(+)). Four MRE-based parameters were evaluated to analyze the skull-brain decoupling performance: brain-to-skull rotational transmission ratio (Rtr), cortical shear strain (normalized OSS (octahedral shear strain)), cortical volumetric strain (normalized ONS (octahedral normal strain)), and the OSS-to-ONS ratio. Confounding factors (age/skull-brain distance, sex) were controlled with a linear regression model. One-way ANOVA with Tukey's post-hoc test was used for group comparisons.

RESULTS

The high RHI(+) showed a significantly increased adjusted Rtr compared to the RHI(-) and low RHI(+) (p < 0.001). Higher adjusted OSS-to-ONS ratios were found in the high RHI(+) in the frontal (q < 0.05), parietal (q < 0.001), and occipital (q < 0.05) lobes compared to the RHI(-), and in all regions compared to the low RHI(+) (q < 0.05). The high RHI(+) exhibited lower adjusted normalized ONS and OSS in the temporal lobe (q < 0.05) compared to the low RHI(+). These findings suggest that recent and prolonged RHI exposures may impair the skull-brain decoupling performance, affecting the capacity of the interface to isolate the brain by dampening skull-to-brain motion transmission and modulating brain surface deformation.

CONCLUSION

This study reveals evidence of impaired decoupling function at the skull-brain interface resulting from RHI exposure and demonstrates MRE-based biomarkers for early detection of this impairment.

KEY POINTS

Question The skull-brain interface is crucial for brain protection under impact, but its early mechanical responses to repetitive head impacts (RHIs) remain largely unknown. Findings Mechanical changes (more rotation and a shift in shear relative to volumetric strain) across the skull-brain interface were observed in participants under high RHI exposure. Clinical relevance Our study developed MR elastography (MRE)-based measurements to detect changes in the skull-brain interface caused by RHI, suggesting that MRE holds promise for noninvasively quantifying cumulative injury and potential future clinical interventions for individuals with high RHI exposure.

The Amyloid Cascade Hypothesis: A Conclusion in Search of Support

The amyloid cascade hypothesis as the etiological underpinning of Alzheimer disease (AD) is supported by a large body of literature, the most influential of which are genetic studies of the 1980s and 1990s. Other evidence includes the neuropathology of Down syndrome, apparent toxicity of oligomeric amyloid-β (Aβ), interactions with apolipoprotein E, and the analogy of cardiac amyloidosis. On the other hand, there is considerable phenotypic heterogeneity among the rare familial AD kindreds, which tempers extrapolation to sporadic AD. Oligomer biology is still in the theoretical realm, with no clinical validation. Apolipoprotein E support for the amyloid cascade and other inferences from the literature are somewhat circular in their logic. Analogy with amyloidoses might also consider secondary amyloidosis, driven by systemic inflammation and treated by treating the underlying etiology. Much of the remaining literature supporting the amyloid cascade is dominated by hypothesis-generating studies. Importantly, we now have a developing evidence base from controlled clinical trials that can potentially inform the issue of Aβ as a cause or driver of disease in sporadic AD. Emerging data provide clear evidence of target engagement. Clinical outcome, however, has been either marginally positive or similar to placebo. Assuming these findings hold, it appears that Aβ neither drives nor mitigates the disease process.

Time to level the playing field between men and women - Given similar injury incidence: A two-season analysis of match injuries in elite men and women's (Super League) rugby league

OBJECTIVES

To compare match injury incidence, severity and burden in men's and women's elite rugby league.

DESIGN

A prospective cohort epidemiological study.

METHODS

Time loss match injury data were collected from all men's (11,301 exposure hours) and women's (5,244 exposure hours) Super League clubs.

RESULTS

Injury incidence and burden were not different between men and women (mean [95 % CI]; 54 [45 to 65] vs. 60 [49 to 74] per 1000 match-hours; p = 0.39, and 2332 [1844 to 2951] vs. 1951 [1560 to 2440] days lost per 1000 match-hours; p = 0.26). However, injury severity was greater for men than women (42 [35-50] vs. 35 [29 to 42]; p = 0.01). Lower limbs accounted for 54 % and 52 % of injuries for men and women, with the head/face the most frequently injured location due to concussion (12 [10 to 15] and 10 [8 to 14] per 1000 match-hours for men and women). Injuries to the knee had the greatest burden for men and women (708 [268-1868] and 863 [320-2328] days lost per 1000 match-hours). Being tackled was the most common injury mechanism for men and women (28 % and 38 %) with greater burden (p < 0.01) than other injury mechanisms.

CONCLUSIONS

Male and female rugby league players have similar injury incidence and burden; however, injury severity was higher in men. Head/face injuries have the highest injury incidence and knee injuries have the highest burden. These injuries should be the focus for prevention initiatives at a league (via laws), player, and coach level, with equal and specific focus for both men's and women's rugby league players.

Career duration and later-life health conditions among former professional American-style football players

OBJECTIVES

Career duration is often used as a metric of neurotrauma exposure in studies of elite athletes. However, as a proxy metric, career length may not accurately represent causal factors, and associations with health outcomes may be susceptible to selection effects. To date, relationships between professional American-style football (ASF) career length and postcareer health remain incompletely characterised.

METHODS

We conducted a survey-based cross-sectional cohort study of former professional ASF players. Flexible regression methods measured associations between self-reported career duration and four self-reported health conditions: pain, arthritis, mood and cognitive symptoms. We also measured associations between career duration and four self-reported ASF exposures: prior concussion signs and symptoms (CSS), performance enhancing drugs, intracareer surgeries and average snaps per game. Models were adjusted for age and race.

RESULTS

Among 4189 former players (52±14 years of age, 39% black, 34% lineman position), the average career length was 6.7±3.9 professional seasons (range=1-20+). We observed inverted U-shaped relationships between career duration and outcomes (all p<0.001), indicating that adverse health effects were more common among men with intermediate career durations than those with shorter or longer careers. Similar findings were observed for play-related exposures (eg, CSS and snaps).

CONCLUSIONS

Relationships between ASF career duration and subsequent health status are non-linear. Attenuation of the associations among longer career players may reflect selection effects and suggest career length may serve as a poor proxy for true causal factors. Findings highlight the need for cautious use of career duration as a proxy exposure metric in studies of former athletes.

Age of First Exposure Does Not Relate to Post-Career Health in Former Professional American-Style Football Players

OBJECTIVE

Prior studies examining small samples of symptomatic former professional football players suggest that earlier age of first exposure (AFE) to American football is associated with adverse later life health outcomes. This study examined a larger, more representative sample of former professional American football players to assess associations between AFE before age 12 (AFE < 12) and clinical outcomes compared with those who started at age 12 or older (AFE 12 +).

METHODS

Former professional American football players who completed a questionnaire were dichotomized into AFE < 12 and AFE 12 + . AFE groups were compared on outcomes including symptoms of depression and anxiety, perceived cognitive difficulties, neurobehavioral dysregulation, and self-reported health conditions (e.g., headaches, sleep apnea, hypertension, chronic pain, memory loss, dementia/Alzheimer's disease, and others).

RESULTS

Among 4189 former professional football players (aged 52 ± 14 years, 39% self-reported as Black), univariable associations with negligible effect sizes were seen with AFE < 12, depressive symptoms (p = 0.03; η2 = 0.001), and anxiety-related symptoms (p = 0.02; η2 = 0.001) only. Multivariable models adjusting for age, race, body mass index, playing position, number of professional seasons, and past concussion burden revealed no significant relationships between AFE < 12 and any outcome. Linear and non-linear models examining AFE as a continuous variable showed similar null results.

CONCLUSIONS

In a large cohort of former professional American-style football players, AFE was not independently associated with adverse later life outcomes. These findings are inconsistent with smaller studies of former professional football players. Studies examining AFE in professional football players may have limited utility and generalizability regarding policy implications for youth sports.

Training and Match-Related Head Acceleration Events in Top Level Domestic Senior Women's and Men's Rugby Union: A Multi-League Instrumented Mouthguard Study

The aim of this study was to investigate the difference in head acceleration event (HAE) incidence between training and match-play in women's and men's players competing at the highest level of domestic rugby union globally. Players from Women's (Premiership Women's Rugby, Farah Palmer Cup) and Men's (Premiership Rugby, Currie Cup) rugby union competitions wore instrumented mouthguards during matches and training sessions during the 2022/2023 seasons. Peak linear (PLA) and angular (PAA) acceleration were calculated from each HAE and included within generalized linear mixed-effects models. The incidence of HAEs was significantly greater in match-play compared to training for all magnitude thresholds in both forwards and backs, despite players spending approximately 1.75-2.5 times more time in training. For all HAEs (PLA > 5 g and PAA > 400 rad/s2), incidence rate ratios (IRRs) for match versus training ranged from 2.80 (95% CI: 2.38-3.30; men's forwards) to 4.00 (3.31-4.84; women's forwards). At higher magnitude thresholds (PLA > 25 g; PAA > 2000 rad/s2), IRRs ranged from 3.64 (2.02-6.55; PAA > 2000 rad/s2 in men's backs) to 11.70 (6.50-21.08; PAA > 2000 rad/s2 in women's forwards). Similar trends were observed in each competition. Players experienced significantly more HAEs during match-play than training, particularly at higher magnitude thresholds. Where feasible, HAE mitigation strategies may have more scope for HAE reduction if targeted at match-play, particularly where higher magnitude HAEs are the primary concern. However, the number of HAEs associated with different training drills requires exploration to understand if HAEs can be reduced in training, alongside optimizing match performance (e.g., enhancing contact technique).

Repetitive Subconcussive Head Impacts in Sports and Their Impact on Brain Anatomy and Function: A Systematic Review

Repetitive subconcussive head impacts occur regularly in sports. However, the exact relationship between their biomechanical properties and their consequences on brain structure and function has not been clarified yet. We therefore reviewed prospective cohort studies that objectively reported the biomechanical characteristics of repetitive subconcussive head impacts and their impact on brain anatomy and function. Only studies with a pre- to post-measurement design were included. Twenty-four studies met the inclusion criteria. Structural white matter alterations, such as reduced fractional anisotropy and an increase in mean diffusivity values, seem to be evident in athletes exposed to repetitive subconcussive head impacts exceeding 10 g. Such changes are observable after only one season of play. Furthermore, a dose-response relationship exists between white matter abnormalities and the total number of subconcussive head impacts. However, functional changes after repetitive subconcussive head impacts remain inconclusive. We therefore conclude that repetitive subconcussive head impacts induce structural changes, but thus far without overt functional changes.

Longitudinal Assessment of Selective Motor Dysfunction in Service Members With Combat-Related Mild TBI

INTRODUCTION

Evaluations of clinical outcomes in service members with mild traumatic brain injury (TBI) sustained in combat have largely focused on neurobehavioral and somatic symptoms, neurocognitive functioning, and psychological/psychiatric health. Questions remain regarding other domains, such as gross or fine motor abilities, that could be impacted and are mission-critical to functional warfighters.

MATERIALS AND METHODS

The objective of the current study was to evaluate longitudinal motor function in U.S. Military personnel with and without mild TBI sustained in combat to assess the possible long-term impact. Data from the EValuation Of Longitudinal outcomes in mild TBI active duty military and VEterans (EVOLVE) study were leveraged for analysis. The EVOLVE study has evaluated and followed service members from combat and following medical evacuation with and without blast-related mild TBI, as well as blunt impact mild TBI, and noninjured combat-deployed service members, tracking 1-, 5-, and 10-year outcomes. Longitudinal demographic, neuropsychological, and motor data were leveraged. Cross-sectional differences in outcomes at each year among the 4 injury groups were assessed using rank regression, adjusting for age, education, sex, branch of service (Army vs. other), subsequent head injury exposure, and separation from service. To understand the possible performance impact of time on all the measures, mixed-effects rank regression was employed, assessing time with adjustments for group, age, education, subsequent head injury exposure, and service separation status, followed by Benjamini-Hochberg correction for multiple comparisons.

RESULTS

Evaluation for cognitive performance across 19 primary measures of interest at 1, 5, and 10 years did not identify any significant differences; however, gross motor function was found to be significantly different across groups at all time points (adjusted P < .001 at 1 year, P = .004 at 5 years, and P < .001 at 10 years) with both TBI groups consistently performing slower on the 25-Foot Walk and Grooved Pegboard than the nonblast control groups. While there were no cross-sectional differences across groups, many cognitive and motor measures were found to have significant changes over time, though not always in the direction of worse performance. Selective motor impairment in both TBI groups was identified compared to nonblast controls, but all groups were also found to exhibit a level of motor slowing when comparing performance at 1- to 10-year follow-ups.

CONCLUSIONS

Assessment of gross motor function reflected a consistent pattern of significantly slower performances for blast and nonblast TBI groups compared to controls, over all follow-up intervals. Fine motor function performance reflected a similar significant difference pattern at 1- and 5-year follow-up intervals, with a reduced difference from control groups at the 10-year follow-up. Maintenance of high-level motor functions, including overall motor speed, coordination, and reaction time, is a primary component for active warfighters, and any motor-related deficits could create an increased risk for the service member or unit. While the service members in this longitudinal study did not meet criteria for any specific clinical motor-related diagnoses or movement disorders, the finding of motor slowing may reflect a subclinical but significant change that could be a focus for intervention to return to preinjury levels.

American Football On-Field Head Impact Kinematics: Influence of Acceleration Signal Characteristics on Peak Maximal Principal Strain

Recorded head kinematics from head-impact measurement devices (HIMd) are pivotal for evaluating brain stress and strain through head finite element models (hFEM). The variability in kinematic recording windows across HIMd presents challenges as they yield inconsistent hFEM responses. Despite establishing an ideal recording window for maximum principal strain (MPS) in brain tissue, uncertainties persist about the impact characteristics influencing vulnerability when this window is shortened. This study aimed to scrutinize factors within impact kinematics affecting the reliability of different recording windows on whole-brain peak MPS using a validated hFEM. Utilizing 53 on-field head impacts recorded via an instrumented mouthguard during a Canadian varsity football game, 10 recording windows were investigated with varying pre- and post-impact-trigger durations. Tukey pair-wise comparisons revealed no statistically significant differences in MPS responses for the different recording windows. However, specific impacts showed marked variability up to 40%. It was found, through correlation analyses, that impacts with lower peak linear acceleration exhibited greater response variability across different pre-trigger durations. Signal shape, analyzed through spectral analysis, influenced the time required for MPS development, resulting in specific impacts requiring a prolonged post-trigger duration. This study adds to the existing consensus on standardizing HIMd acquisition time windows and sheds light on impact characteristics leading to peak MPS variation across different head impact kinematic recording windows. Considering impact characteristics in research assessments is crucial, as certain impacts, affected by recording duration, may lead to significant errors in peak MPS responses during cumulative longitudinal exposure assessments.

Sports Related Concussion

Sports-related concussions (SRC) have been a topic of interest for decades and are a prevalent risk of sports participation. The definition of SRC continues to evolve but includes a plausible mechanism and associated symptoms of injury. Rates of concussion vary among sports, and many sports have adopted rule changes to limit this risk for its athletes. There has been a considerable effort to prevent the occurrence of SRC, as well as a focus on safe return to learn and sport alike. There is growing concern about the ramifications of concussions, which will continue to warrant further investigation.

Time to resolution of symptoms and recovery after mild traumatic brain injury: protocol for a systematic review and meta-analysis

INTRODUCTION

Mild traumatic brain injury (mTBI) is a leading cause of morbidity and mortality, with approximately 1 out of 200 people each year sustaining an mTBI in Europe. There is a growing awareness that recovery may take months or years. However, the exact time frame of recovery remains ill-defined in the literature. This systematic review aims to record the range of outcome measures used for mTBI and understand the time to recovery for different outcomes.

METHODS AND ANALYSIS

This protocol complies with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guideline. A prespecified literature search for articles in the English language will be conducted from database inception to the date of searches using MEDLINE and EMBASE. A trial search was conducted on 5 October 2023 with refinement of the search criteria following this. For each study, screening of the title, abstract and full text, as well as data extraction, will be done by two reviewers, with an adjudicating third reviewer if required. The risk of bias will be assessed using the Cochrane risk of bias tool for clinical trials and the Newcastle Ottawa score for cohort studies. The primary outcome is the time to resolution of symptoms in mTBI patients who have a full recovery, using any validated outcome measure. Results will be categorised by symptom groups, including but not limited to post-concussive symptoms, mental health, functional recovery and health-related quality of life. For mTBI patients who do not recover, this review will also explore the time to the plateau of symptoms and the sequelae of these symptoms. Where possible, meta-analysis will be undertaken, with a narrative review undertaken when this is not possible. Subgroup analyses of patients aged over 64 years, and patients with repetitive head injury, are planned.

ETHICAL REVIEW AND DISSEMINATION

Ethical review is not required, as no original data will be collected. Results will be disseminated through peer-reviewed publications and academic conferences.

PROSPERO REGISTRATION NUMBER

CRD42023462797.

Effects of Cumulative Head Impact Exposure in Adolescent Male Contact and Collision Sport Student Athletes

OBJECTIVE

This prospective cohort study aimed to investigate the association between head impact exposure (HIE) and neuropsychological sequelae in high school football and ice hockey players over 1 year.

SETTING

Community sample.

PARTICIPANTS

A cohort of 52 adolescent American football and ice hockey players were enrolled in the study, with a final study sample of 35 included in analyses.

DESIGN

The study followed a prospective cohort design, with participants undergoing neuropsychological screening and accelerometer-based measurement of HIE over 1 season.

MAIN MEASURES

Changes in cognition, emotions, behavior, and reported symptoms were assessed using standardized neuropsychological tests and self-reported questionnaires.

RESULTS

Cumulative HIE was not consistently associated with changes in cognition, emotions, behavior, or reported symptoms. However, it was linked to an isolated measure of processing speed, showing inconsistent results based on the type of HIE. History of previous concussion was associated with worsened verbal memory recognition (ImPACT Verbal Memory) but not on a more robust measure of verbal memory (California Verbal Learning Test [CVLT]). Reported attention-deficit/hyperactivity disorder history predicted improved neurocognitive change scores. No associations were found between reported history of anxiety/depression or headaches/migraines and neuropsychological change scores.

CONCLUSION

Overall, our findings do not support the hypothesis that greater HIE is associated with an increase in neuropsychological sequelae over time in adolescent football and ice hockey players. The results align with the existing literature, indicating that HIE over 1 season of youth sports is not consistently associated with significant neuropsychological changes. However, the study is limited by a small sample size, attrition over time, and the absence of performance validity testing for neurocognitive measures. Future studies with larger and more diverse samples, longer follow-up, and integration of advanced imaging and biomarkers are needed to comprehensively understand the relationship between HIE and neurobehavioral outcomes. Findings can inform guidelines for safe youth participation in contact sports while promoting the associated health and psychosocial benefits.

The way to relieve college students' academic stress: the influence mechanism of sports interest and sports atmosphere

BACKGROUND AND RESEARCH OBJECTIVES

Given the enduring popularity of higher education, there has been considerable attention on the correlation between college students' engagement in sports and their academic stress levels. This study seeks to delve deeply into how university physical education fosters academic performance by influencing students' sports interests, particularly in enhancing their psychological resilience to mitigate academic pressure. Through this investigation, the aim is to offer both theoretical underpinnings and empirical evidence to support the holistic enhancement of higher education.

RESEARCH METHODS

Initially, this study undertakes an analysis of the fundamental relationship between college students' physical activities and their experience of academic stress. Subsequently, utilizing a structural equation model, specific research models and hypotheses are formulated. These are then examined in detail through the questionnaire method to elucidate the mechanism by which college sports interests alleviate academic stress.

RESEARCH FINDINGS

The study reveals a significant positive correlation between psychological resilience and academic stress, indicating that a robust psychological resilience can effectively diminish academic pressure. Furthermore, both the sports atmosphere and sports interest are found to exert a notable positive impact on academic stress, mediated by the variable of psychological toughness. This underscores the pivotal role of physical education in fostering positive psychological traits and enhancing academic achievement.

CONCLUSION

This study underscores the central importance of cultivating and nurturing college students' sports interests, as well as fostering a conducive sports atmosphere, in fortifying psychological resilience and mitigating academic pressure. By offering novel perspectives and strategies for alleviating the academic stress faced by college students, this study contributes valuable theoretical insights and practical experiences to the broader development of higher education.

Head Acceleration Events During Tackle, Ball-Carry, and Ruck Events in Professional Southern Hemisphere Men's Rugby Union Matches: A Study Using Instrumented Mouthguards

OBJECTIVES

Describe head acceleration events (HAEs) experienced by professional male rugby union players during tackle, ball-carry, and ruck events using instrumented mouthguards (iMGs).

DESIGN

Prospective observational cohort.

METHODS

Players competing in the 2023 Currie Cup (141 players) and Super Rugby (66 players) seasons wore iMGs. The iMG-recorded peak linear acceleration (PLA) and peak angular acceleration (PAA) were used as in vivo HAE approximations and linked to contact-event data captured using video analysis. Using the maximum PLA and PAA per contact event (HAEmax), ordinal mixed-effects regression models estimated the probabilities of HAEmax magnitude ranges occurring, while accounting for the multilevel data structure.

RESULTS

As HAEmax magnitude increased the probability of occurrence decreased. The probability of a HAEmax ≥15g was 0.461 (0.435-0.488) (approximately 1 in every 2) and ≥45g was 0.031 (0.025-0.037) (1 in every 32) during ball carries. The probability of a HAEmax >15g was 0.381 (0.360-0.404) (1 in every 3) and >45g 0.019 (0.015-0.023) (1 in every 53) during tackles. The probability of higher magnitude HAEmax occurring was greatest during ball carries, followed by tackles, defensive rucks and attacking rucks, with some ruck types having similar profiles to tackles and ball carries. No clear differences between positions were observed.

CONCLUSION

Higher magnitude HAEmax were relatively infrequent in professional men's rugby union players. Contact events appear different, but no differences were found between positions. The occurrence of HAEmax was associated with roles players performed within contact events, not their actual playing position. Defending rucks may warrant greater consideration in injury prevention research.

Navigating uncertainty: exploring parents' knowledge of concussion management and neuropsychological baseline testing

Introduction

Parents play an important role in preventing and managing sport-related concussions among youth sport participants. Research indicates that parents understand the severity and consequences associated with the injury but gaps exist in their knowledge of its management. Neuropsychological baseline testing (NBT) is a modality that has gained interest in youth sport to purportedly better manage concussion injuries. Little is known about parents' perspectives on the use of NBT in the management process.

Methods

The present qualitative study used Protection Motivation Theory as a guiding framework and employed focus groups (N = 2) with parents (N = 11) to gain insight into parents' perceptions and experiences with concussion management, specifically focusing on NBT.

Results

Inductive Content Analysis developed a core theme of navigating uncertainty. Participants expressed uncertainty about the nature of concussion and its management process, where concussion was not always easy to identify, youth were not always reliable reporters, and there was no prescribed or proscribed path for recovery. Personal experience and concussion management policy provided participants with a degree of certainty in managing concussions. Participants gave NBT mixed reviews in potentially promoting greater certainty but also held reservations about its usefulness in concussion management.

Discussion

We discuss findings relative to existing knowledge and theory in youth sport concussion and identify implications for practice.

Repetitive head-injury exposure and later-in-life cognitive and emotional outcomes among former collegiate football players: a CLEAATS investigation

This study measured the relationship between head-injury exposure and later-in-life cognitive and emotional symptoms in aging collegiate football players who participated in the College Level Aging Athlete Study. Linear regressions examined the relationship between various head-injury exposure variables (head-injury exposure estimate [HIEE], number of diagnosed concussions, and symptomatic hits to the head) and subjective cognitive function, objective cognitive function, and emotional/mood symptoms. Additional regressions evaluated the impact of emotional symptoms on subjective cognitive decline and objective cognitive function. Participants (n = 216) were 50-87 years old (M = 63.4 [8.5]), 91% White, and well-educated (bachelor's/graduate degree = 92%). HIEE did not predict scores on cognitive or emotional/mood symptom measures (p's > .169). Diagnosed concussions had a small effect on depression symptoms (p = .002, b = 0.501, R2 = .052) and subjective cognitive symptoms (p = .002, b = 0.383, R2 = .051). An emotional symptom index had a stronger relationship (p < .001, b = 0.693, R2 = .362) with subjective cognitive functioning but no significant relationship with objective cognitive function (p = .052, b = -0.211, R2 = .020). Controlling for emotional symptoms, the relationship between concussions and subjective cognitive symptoms was attenuated (p = .078, R2 = .011). Findings suggested that head-injury exposure was not significantly related to cognitive or emotional/mood outcomes in former collegiate football players and highlighted the importance of current emotional/mood symptoms on subjective cognitive function.

Concussion incidence and mechanisms differ between elite females and males in Australian Football

OBJECTIVES

To investigate the incidence and the game circumstances of concussion in the professional female (AFLW) and male (AFL) competitions of Australian Football, to identify potential targets for risk reduction.

DESIGN

Retrospective cohort.

METHODS

Concussion data were obtained from the AFL injury database, which included all concussions sustained by AFL (Male) players from 2015 to 18 and AFLW (Female) players from 2017 to 19. Concussions were diagnosed by experienced clinicians utilising standardised concussion assessment tools and injury definitions, as well as video review. Video footage was analysed to determine the circumstances each concussion occurred, which included the action and the contact-point of impact.

RESULTS

The incidence of concussion was higher in the AFLW (Female) compared to the AFL (Male) (IRR = 2.12, 95 %CI 1.54 to 2.92). Video footage was available for 194/252 (77 %) concussions in the AFL and 35/44 (80 %) concussions in the AFLW. Male players were most frequently concussed during marking contests (28 %) with primary impact from the upper limb (22 %) or the shoulder (19 %). Conversely, being bumped (23 %) or tackled (20 %) were the main actions associated with concussion in female players, with the head (29 %) or the ground (23 %) the most common contact-points of impact.

CONCLUSIONS

In elite Australian Football a higher incidence of concussion was demonstrated in female compared to male players. The mechanisms associated with concussion were also found to differ between male and female competitions, suggesting that different injury prevention interventions may be beneficial. In particular, a review of tackling and bumping skills training and education in the AFLW may reduce the risk of concussion.

Kumanu Tāngata: the aftermatch study - protocol to examine the health outcomes of high-level male rugby union players using linked administrative data

There is increasing interest in the potential long-term outcomes of participation in contact and collision sports, driven by evidence of higher rates of neurodegenerative diseases among former athletes. Recent research has capitalised on large-scale administrative health data to examine health outcomes in contact sport athletes. However, there is limited research on outcomes associated with participation in rugby union, a contact sport with a relatively high incidence of head trauma and musculoskeletal injuries. Additionally, there is scope to investigate a greater range of health outcomes using large, population-based administrative data. The Kumanu Tāngata project is a retrospective cohort study that will use linked information from the New Zealand Rugby Register and health records within a comprehensive deidentified whole-population administrative research database known as the Integrated Data Infrastructure. First-class male rugby union players (N=13 227) will be compared with a general population comparison group (N=2 438 484; weighting will be applied due to demographic differences) on a range of mortality and morbidity outcomes (neurodegenerative diseases, musculoskeletal conditions, chronic physical conditions, mental health outcomes). A range of player-specific variables will also be investigated as risk factors. Analyses will consist primarily of Cox proportional hazards models. Ethics approval for the study has been granted by the Auckland Health Research Ethics Committee (Ref. AH23203). Primary research dissemination will be via peer-reviewed journal articles.

Role of regulatory non-coding RNAs in traumatic brain injury

Traumatic brain injury (TBI) is a potentially fatal health event that cannot be predicted in advance. After TBI occurs, it can have enduring consequences within both familial and social spheres. Yet, despite extensive efforts to improve medical interventions and tailor healthcare services, TBI still remains a major contributor to global disability and mortality rates. The prompt and accurate diagnosis of TBI in clinical contexts, coupled with the implementation of effective therapeutic strategies, remains an arduous challenge. However, a deeper understanding of changes in gene expression and the underlying molecular regulatory processes may alleviate this pressing issue. In recent years, the study of regulatory non-coding RNAs (ncRNAs), a diverse class of RNA molecules with regulatory functions, has been a potential game changer in TBI research. Notably, the identification of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and other ncRNAs has revealed their potential as novel diagnostic biomarkers and therapeutic targets for TBI, owing to their ability to regulate the expression of numerous genes. In this review, we seek to provide a comprehensive overview of the functions of regulatory ncRNAs in TBI. We also summarize regulatory ncRNAs used for treatment in animal models, as well as miRNAs, lncRNAs, and circRNAs that served as biomarkers for TBI diagnosis and prognosis. Finally, we discuss future challenges and prospects in diagnosing and treating TBI patients in the clinical settings.

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.

The spectrum of acute and chronic consequences of neurotrauma in professional and amateur boxing - A call to action is advocated to better understand and prevent this phenomenon

Introduction

Despite changes in regulations, boxing-related injuries and fatalities are still occurring. The numbers available in the literature regarding mortality and long-term consequences may not accurately represent the actual situation. Indeed, the real extent of this phenomenon remains poorly known.

Research question

Delineating the spectrum of acute and chronic consequences of boxing-related traumatic brain injuries (TBI).

Material and methods

Narrative review of the literature concerning acute and chronic boxing-related TBI. Keywords such as mortality, boxing, subdural hematoma were used to search in PubMed and Google scholar. An updated analysis of the Velazquez fatalities collection in boxing was undertaken.

Results

The Velazquez collection includes 2076 fatalities from 1720 to the present with a death rate of 10 athletes per year. More than half of the deaths (N = 1354, 65.2%) occurred after a knock-out, and nearly 75% happened during professional bouts. In Australia, from 1832 to 2020, 163 fatalities were recorded (75% professional). In Japan, from 1952 to 2016, 38 deaths were recorded with a mean age of 23.9 years. Up to 40% of retired professional boxers in the United States were diagnosed with symptoms of chronic brain injury. Clinical dementia is far more prevalent among professional boxers than in amateurs with an incidence of 20%.

Discussion and conclusions

A concerted effort to raise awareness and shed light on boxing-related neuro-trauma is required. Similar considerations can be made for other combat sports or contact sports. A call to action to address this knowledge gap, decrease and prevent this phenomenon is advocated.

The 50 Most Cited Papers on Rugby since 2000 Reveal a Focus Primarily on Strength and Conditioning in Elite Male Players

We sought to conduct a bibliometric analysis and review of the most cited publications relating to rugby since 2000 in order to identify topics of interest and those that warrant further investigations. Clarivate Web of Science database was used to perform a literature search using the search term "rugby." The top 200 papers by citation count were extracted and reviewed for the inclusion criteria: all subjects were rugby players. The top 50 manuscripts were included for analysis of author, publication year, country of lead authors, institution, journal name and impact factor, topic, participant sex, and level of rugby. The total number of citations was 9,071 (average of 181.4 citations/article), with an average journal impact factor of 7.21; the top article was cited 407 times at the time of analysis. The most frequent publication was the Journal of Strength and Conditioning Research (26%), followed by the British Journal of Sports Medicine (20%) and the Journal of Sports Sciences (18%). Forty-eight (96%) of the manuscripts contained only male subjects, with 1 manuscript including females only and 1 manuscript containing mixed sexes. Thirty-three (66%) of the manuscripts focused on professional rugby players, with the next highest player group being mixed levels (10%). Twenty-eight (56%) concentrated on topics regarding strength and conditioning, 11 (22%) on injury, and 4 (8%) on physiology. Despite rugby being one of the most injurious sports and community players representing the largest component of the player pool, most of the top-cited rugby articles are cohort studies of professional male athletes focused on performance and strength and conditioning, noting the bias in research towards socially relevant topics that may not impact the majority of stakeholders and long-term health of rugby athletes. These findings highlight the need for further research among women and community athletes and on topics in injury prevention.

Incidence of Concussions in Elite Female Water Polo: A Retrospective Analysis

OBJECTIVE

Current evidence for concussions is mixed in water polo players. Surveys suggest rates as high as 36%, whereas surveillance studies at international competitions often fail to report them at all. The goal of this study was to examine the incidence of concussions in elite female water polo players from surveillance tools implemented longitudinally.

DESIGN

Retrospective chart analysis of 10 years spanning between 2012 and 2022.

SETTING

National teams or professional sports.

PARTICIPANTS

Female players from the Canadian senior national water polo teams that participated in international competitions and trained more than 10 hours per week in a competitive environment.

ASSESSMENT OF RISK FACTORS

Included player position, recurrence, and time loss before full return to play.

MAIN OUTCOME MEASURES

Prevalence of concussion diagnosis.

RESULTS

Forty-three concussions were identified over the 10 years observed at a median count of 3 concussions per year. Cumulative days lost spanned between 25 and 348 days per team*year. Altogether, this produced a median rate of 14.3 injuries per 100 player*years. Goalkeepers in the sample suffered the highest rates of concussion (25.8%), compared with players in other positions (22.8% of centers and 16.7% of drivers).

CONCLUSIONS

This study found evidence for prevalence of concussions in elite female water polo players. Improved guidelines preceded a significant reduction in time loss after the year 2017. This adds to a body of knowledge suggesting that improved surveillance methods are needed to detect and care for concussions in this population.

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.

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.

The amyotrophic lateral sclerosis exposome: recent advances and future directions

Amyotrophic lateral sclerosis (ALS) is a fatal disease of motor neuron degeneration with typical survival of only 2-5 years from diagnosis. The causes of ALS are multifactorial: known genetic mutations account for only around 70% of cases of familial ALS and 15% of sporadic cases, and heritability estimates range from 8% to 61%, indicating additional causes beyond genetics. Consequently, interest has grown in environmental contributions to ALS risk and progression. The gene-time-environment hypothesis posits that ALS onset occurs through an interaction of genes with environmental exposures during ageing. An alternative hypothesis, the multistep model of ALS, suggests that several hits, at least some of which could be environmental, are required to trigger disease onset, even in the presence of highly penetrant ALS-associated mutations. Studies have sought to characterize the ALS exposome - the lifetime accumulation of environmental exposures that increase disease risk and affect progression. Identifying the full scope of environmental toxicants that enhance ALS risk raises the prospect of preventing disease by eliminating or mitigating exposures. In this Review, we summarize the evidence for an ALS exposome, discussing the strengths and limitations of epidemiological studies that have identified contributions from various sources. We also consider potential mechanisms of exposure-mediated toxicity and suggest future directions for ALS exposome research.

Improving outcome after paediatric concussion: challenges and possibilities

The term concussion has permeated mainstream media and household vocabulary mainly due to awareness regarding the risks of concussion in professional contact sports, yet it occurs across a variety of settings and ages. Concussion is prevalent in infants, preschoolers, children, and adolescents, and is a common presentation or reason for referral to primary care providers, emergency departments, and specialised trauma clinics. Its broad range of symptoms and sequelae vary according to multiple individual, environmental, and clinical factors and can lead to health and economic burden. More than 20 years of research into risk factors and consequences of paediatric concussion has revealed as many questions as answers, and scientific work and clinical cases continue to expose its complexity and heterogeneity. In this Review, we present empirical evidence for improving outcome after paediatric concussion. We consider work pertaining to both sports and other injury mechanisms to provide a perspective that should be viewed as complementary to publications focused specifically on sports concussion. Contemporary challenges in prevention, diagnosis, prognosis, and intervention are discussed alongside pathways and future directions for improving outcome.