Association of Sex With Adolescent Soccer Concussion Incidence and Characteristics

Association of Alzheimer's Disease Polygenic Risk Score with Concussion Severity and Recovery Metrics

BACKGROUND

Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed.

OBJECTIVE

We used AD polygenic risk scores (PRS) and APOE genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset.

METHODS

We assessed six concussion outcomes in 931 participants, including two recovery measures (number of days to asymptomatic and to return to play (RTP)) and four severity measures (scores on SAC and BESS, SCAT symptom severity and total number of symptoms). We calculated the PRS using a published score and performed multiple linear regression to assess the relationship of the PRS with outcomes. We also used ANOVAs, t-tests, and chi-square tests to examine outcomes by APOE genotype.

RESULTS

Higher PRS was associated with longer injury to RTP time in the normal RTP (< 24 days) subgroup (p = 0.024). A one standard deviation increase in the PRS resulted in a 9.89 hour increase to RTP time. This result was no longer significant after inclusion of covariates. There were no other consistently significant effects.

CONCLUSIONS

Our findings suggest high AD genetic risk is not associated with more severe concussions or poor recovery in young adults. Future studies should attempt to replicate these findings in larger samples with longer follow-up using PRS calculated from diverse populations.

Long-term neurobehavioral and neuroimaging outcomes in athletes with prior concussion(s) and head impact exposure

Objective: The long-term health of former athletes with a history of multiple concussions and/or repetitive head impact (RHI) exposure has been of growing interest among the public. The true proportion of dementia cases attributable to neurotrauma and the neurobehavioral profile/sequelae of multiple concussion and RHI exposure among athletes has been difficult to determine. Methods: Across three exposure paradigms (i.e. group comparisons of athletes vs. controls, number of prior concussions, and level of RHI exposure), this review characterizes the prevalence of neurodegenerative/neurological disease, changes in cognitive and psychiatric function, and alterations on neuroimaging. We highlight sources of variability across studies and provide suggested directions for future investigations. Results: The most robust finding reported in the literature suggests a higher level of symptom endorsement (general, psychiatric, and cognitive) among those with a greater history of sport-related concussion from adolescence to older adulthood. Pathological processes (e.g. atrophy, tau deposition, and hypometabolism) may be more likely to occur within select regions (frontal and temporal cortices) and structures (thalamus and hippocampus). However, studies examining concussion(s) and RHI exposure with imaging outcomes have yet to identify consistent associations or evidence of a dose-response relationship or a threshold at which associations are observed. Discussion: Studies have not observed a simple dose-response relationship between multiple concussions and/or RHI exposure with cognitive, psychiatric, or in vivo neurobiological outcomes, particularly at lower levels of play. The relationship between prior concussion and RHI exposure with long-term outcomes in former athletes is complex and likely influenced by -several non-injury-related factors.

College students' perceptions of concussion: Illness beliefs and masculinity norms predict stigma and willingness to seek treatment

College students' beliefs and attitudes concerning concussion, and masculinity norms, were examined in relation to stigma and willingness to seek treatment for possible concussion. Beliefs were measured using a revised Illness Perception Questionnaire (IPQ). Participants: Participants were 631 undergraduates at a Northeastern university, most of whom were nonathletes with no concussion. Methods: Data were collected online. Regression analysis were performed to identify predictors of stigma and treatment willingness. Results: Beliefs that concussion symptoms reflect malingering, are controllable, and have psychological causes were related to more stigmatizing attitudes, as was endorsement of masculinity norms regarding winning and risk-taking. Believing that concussion symptoms are long-lasting and endorsing competitiveness, pain discounting, and self-reliance predicted willingness to seek treatment. Preliminary structural models showed adequate fit. Conclusions: In addition to beliefs assessed by the IPQ, traditional conceptions of masculinity warrant greater attention in the study of concussion-related stigma and willingness to seek treatment.

Association of concussion history with psychiatric symptoms, limbic system structure, and kynurenine pathway metabolites in healthy, collegiate-aged athletes

Psychiatric outcomes are commonly observed in individuals with repeated concussions, though their underlying mechanism is unknown. One potential mechanism linking concussion with psychiatric symptoms is inflammation-induced activation of the kynurenine pathway, which is thought to play a role in the pathogenesis of mood disorders. Here, we investigated the association of prior concussion with multiple psychiatric-related outcomes in otherwise healthy male and female collegiate-aged athletes (N = 212) with varying histories of concussion recruited from the community. Specially, we tested the hypotheses that concussion history is associated with worse psychiatric symptoms, limbic system structural abnormalities (hippocampal volume, white matter microstructure assessed using neurite orientation dispersion and density imaging; NODDI), and elevations in kynurenine pathway (KP) metabolites (e.g., Quinolinic acid; QuinA). Given known sex-effects on concussion risk and recovery, psychiatric outcomes, and the kynurenine pathway, the moderating effect of sex was considered for all analyses. More concussions were associated with greater depression, anxiety, and anhedonia symptoms in female athletes (ps ≤ 0.005) and greater depression symptoms in male athletes (p = 0.011). More concussions were associated with smaller bilateral hippocampal tail (ps < 0.010) and left hippocampal body (p < 0.001) volumes across male and female athletes. Prior concussion was also associated with elevations in the orientation dispersion index (ODI) and lower intracellular volume fraction in several white matter tracts including the in uncinate fasciculus, cingulum-gyrus, and forceps major and minor, with evidence of female-specific associations in select regions. Regarding serum KP metabolites, more concussions were associated with elevated QuinA in females and lower tryptophan in males (ps ≤ 0.010). Finally, serum levels of QuinA were associated with elevated ODI (male and female athletes) and worse anxiety symptoms (females only), while higher ODI in female athletes and smaller hippocampal volumes in male athletes were associated with more severe anxiety and depression symptoms (ps ≤ 0.05). These data suggest that cumulative concussion is associated with psychiatric symptoms and limbic system structure in healthy athletes, with increased susceptibility to these effects in female athletes. Moreover, the associations of outcomes with serum KP metabolites highlight the KP as one potential molecular pathway underlying these observations.

Traumatic Brain Injury and Alzheimer's Disease Biomarkers: A Systematic Review of Findings from Amyloid and Tau Positron Emission Tomography

Traumatic brain injury (TBI) has been discussed as a risk factor for Alzheimer's disease (AD) due to its association with AD risk and earlier cognitive symptom onset. However, the mechanisms behind this relationship are unclear. Some studies have suggested TBI may increase pathological protein deposition in an AD-like pattern; others have failed to find such associations. This review covers literature that uses positron emission tomography (PET) of β-amyloid (Aβ) and/or tau to examine individuals with a history of TBI who are at increased risk for AD due to age. A comprehensive literature search was conducted on January 9, 2023, and 26 resulting citations met inclusion criteria. Common methodological concerns included small samples, limited clinical detail about participants' TBI, recall bias due to reliance on self-reported TBI, and an inability to establish causation. For both Aβ and tau, results were widespread but inconsistent. The regions that showed the most compelling evidence for increased Aβ deposition were the cingulate gyrus and cuneus/precuneus. Evidence for elevated tau was strongest in the medial temporal lobe, entorhinal cortex, precuneus, and frontal, temporal, parietal, and occipital lobes. However, conflicting findings across most regions in both Aβ- and tau-PET studies indicate the critical need for future work in expanded samples and with greater clinical detail to offer a clearer picture of the relationship between TBI and protein deposition in older individuals at risk for AD.

Pediatric Concussion Injuries in Soccer: Emergency Department Trends in the United States From 2012 to 2023

Background

Because of growing concerns regarding repeated head trauma, in 2016, the United States Soccer Federation (USSF) banned headers for athletes aged ≤10 years and limited athletes aged 11 to 13 years to practicing headers for 30 minutes per week.

Purpose

To assess whether the USSF header policy was associated with fewer soccer-related concussions after the 2015 season.

Study Design

Descriptive epidemiology study.

Methods

A retrospective cohort from the National Electronic Injury Surveillance System database was assessed. Age, sex, and injury type were extracted for all soccer-related emergency department visits between January 1, 2012, and December 31, 2023. Univariate and multiple regression analyses were used to assess concussions as a percentage of all soccer-related injuries based on sex, age group (6-9, 10-13, and 14-17 years), and year. The following time frames were assessed: 2012-2015, 2016-2019, and 2020-2023.

Results

The proportion of concussions decreased from 8.2% of all soccer-related injuries in 2012-2015 to 6.1% in 2020-2023 (P < .01). The relative risk reduction for soccer-related concussions presenting to an emergency department in 2020-2023 compared with 2012-2015 was 25.6%. Overall, the proportion of concussions among 10- to 13-year-old and 14- to 17-year-old players was higher than for 6- to 9-year-old players (6.6% and 8.9% vs 4.9%, respectively; P < .01). Despite having a lower frequency of soccer-related injuries overall, female players had a greater proportion of concussions than male players (9.6% vs 6.2% of all soccer-related injuries; P < .01). In the multiple regression analysis, injuries that occurred in 2020-2023 were associated with lower odds of concussion compared with 2012-2015 (odds ratio [OR], 0.75 [95% CI, 0.69-0.81]). Compared with 6- to 9-year-old and male players, the 10- to 13-year-old (OR, 1.30 [95% CI, 1.16-1.45]), 14- to 17-year-old (OR, 1.79 [95% CI, 1.61-1.99]), and female players (OR, 1.53 [95% CI, 1.43-1.63]) were associated with higher odds of concussion.

Conclusion

A 25.6% reduction in the relative risk of presenting to the emergency department with a soccer-related concussion was found when comparing 2020-2023 (after USSF header policy implementation) with 2012-2015 (before policy implementation). The USSF youth soccer header policy may improve player safety by reducing head impacts in the pediatric population.

Sex Differences Across Concussion Characteristics in US Service Academy Cadets: A CARE Consortium Study

OBJECTIVE

To describe sex differences in concussion characteristics in US Service Academy cadets.

DESIGN

Descriptive epidemiology study.

SETTING

Four US service academies.

PARTICIPANTS

2209 cadets (n = 867 females, n = 1342 males).

INDEPENDENT VARIABLE

Sex.

OUTCOME MEASURES

Injury proportion ratios (IPR) compared the proportion of injuries by sex (females referent) for injury situation, certainty of diagnosis, prolonged recovery, recurrent injuries, mental status alterations, loss of consciousness (LOC), posttraumatic amnesia (PTA), retrograde amnesia (RGA), motor impairments, delayed symptom presentation, and immediate reporting.

MAIN RESULTS

Concussions from varsity/intercollegiate sports [IPR of 1.73, 95% confidence interval (CI) 1.43-2.10] and intramurals (IPR of 1.53, 95% CI 1.02-2.32) accounted for a larger proportion in males, whereas concussions outside of sport and military activities accounted for a smaller proportion among males (IPR of 0.70, 95% CI 0.58-0.85). The proportion of concussions with prolonged recovery was lower among males (IPR of 0.69, 95% CI 0.60-0.78), while concussions with altered mental status (IPR of 1.23, 95% CI 1.09-1.38), LOC (IPR of 1.67, 95% CI 1.17-2.37), PTA (IPR of 1.94, 95% CI 1.43-2.62), and RGA (IPR of 2.14, 95% CI 1.38-3.31) accounted for a larger proportion among males. A larger proportion of concussions that were immediately reported was observed in males (IPR of 1.15, 95% CI 1.00-2.31). Proportions of other characteristics (e.g., recurrent injuries) were not different between sexes.

CONCLUSIONS

A higher proportion of concussions occurred outside of sport and military training for female cadets, who also displayed proportionally longer recovery times than males, despite males demonstrating a higher proportion of LOC, PTA, and RGA. Possible factors may include different mechanisms of injury outside of sport and military training, different biopsychosocial states associated with sex or injury context, and delayed injury reporting when outside of an observed environment, possibly secondary to perceived stigma about reporting injuries.

Gender differences in female and male Australian football concussion injury: A prospective observational study of emergency department presentations

OBJECTIVE

To examine gender differences in Australian football (AF)-related concussion presentations to EDs in regional Australia.

METHODS

A prospective observational study of patients presenting to 1 of the 10 EDs in Western Victoria, Australia, with an AF-related concussion was conducted. Patients were part of a larger study investigating AF injuries over a complete AF season, including pre-season training and practice matches. Information regarding concussion injuries was extracted from patient medical records, including clinical features, concurrent injuries, mechanism and context of injury. Female and male data were compared with chi-squared and Fisher's exact tests. P < 0.05 was considered significant.

RESULTS

From the original cohort of 1635 patients with AF-related injuries (242 female and 1393 male), 231 (14.1%) patients were diagnosed with concussion. Thirty-eight (15.7%) females had concussions versus 193 (13.9%) males (P > 0.05). Females over the age of 16 were more likely to be concussed than males in the same age range (females n = 26, 68.4% vs males n = 94, 48.7%; P = 0.026). Neurosurgically significant head injury was rare (one case). Similar rates of concurrent injury were found between females 15 (39.5%) and males 64 (33.2%), with neck injury the single most common in 24 (10.3%) concussions. Sixty-nine patients (29%) were admitted for observation or to await the results of scans. The majority of concussions occurred in match play (87.9%). Females were more likely injured in contested ball situations (63.2% vs 37.3%; P < 0.05).

CONCLUSION

Concussion rates for community-level AF presentations to regional EDs were similar between genders. Serious head injury was rare, although hospital admission for observation was common. Concurrent injuries were common, with associated neck injury most often identified. Match play accounted for the majority of head injuries.

Sex Differences in Resource Allocation and Access to Care After Sport-Related Concussion

CONTEXT

After sport-related concussion (SRC), immediate access to a certified athletic trainer (AT) is important to ensure proper treatment. However, resource allocation and coverage may differ between male and female youth sports.

OBJECTIVE

To compare resource allocation between male and female sports in the following areas: (1) rates of immediate on-field evaluation by an AT at the time of injury, (2) time to general health care presentation, and (3) time to SRC clinic presentation.

DESIGN

Retrospective cohort study.

SETTING

Regional sports concussion center.

PATIENTS OR OTHER PARTICIPANTS

Athletes aged 14 to 18 years who presented to a regional sports concussion center from November 2017 to April 2022.

MAIN OUTCOME MEASURE(S)

The primary exposure of interest was sex (male or female). The primary outcome was immediate on-field evaluation by an AT (yes or no). Secondary outcomes included time to general health care and SRC clinic presentation. Descriptive statistics, χ2 analyses, and linear regressions were performed. Covariates included age, history of prior concussions, and statistically significant demographics.

RESULTS

A total of 832 patients with SRC were included (age = 16.2 ± 1.2 years, 66.5% male). Female athletes had lower rates of attention-deficit/hyperactivity disorder (χ2 = 10.404, P = .001) and higher rates of anxiety and depression (χ2 = 12.891, P < .001) compared with male athletes. The average time to presentation to general health care and the SRC clinic did not differ between males and females, but AT on-field evaluation occurred more in male (40.3%) than female (32.3%) athletes (χ2 = 8.677, P = .013). Multivariable linear regression found that AT on-field evaluation was a significant predictor of time to general health care presentation (β = -.085, P = .015) but not SRC clinic presentation (β = -.055, P = .099). History of prior concussions was a significant predictor of time to initial health care contact (β = .083, P = .018). History of anxiety and depression (β = .136, P < .001) and initial evaluation by emergency department or urgent care (β = .305, P < .001) were significant predictors of delayed time to SRC clinic presentation.

CONCLUSIONS

Among 832 concussed youth athletes, female athletes were evaluated less frequently by an AT immediately after injury. Furthermore, not being evaluated by an AT on field was significantly associated with a longer time to health care presentation. Future investigations should elucidate resource equity among male and female athletes.

Association of Alzheimer's disease polygenic risk score with concussion severity and recovery metrics

Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed. We used AD polygenic risk scores (PRS) and APOE genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset. We assessed six outcomes in 931 total participants. The outcomes were two concussion recovery measures (number of days to asymptomatic status, number of days to return to play (RTP)) and four concussion severity measures (scores on SAC and BESS, SCAT symptom severity, and total number of symptoms). We calculated PRS using a published score [1] and performed multiple linear regression (MLR) to assess the relationship of PRS with the outcomes. We also used t-tests and chi-square tests to examine outcomes by APOE genotype, and MLR to analyze outcomes in European and African genetic ancestry subgroups. Higher PRS was associated with longer injury to RTP in the normal RTP (<24 days) subgroup ( p = 0.024), and one standard deviation increase in PRS resulted in a 9.89 hour increase to the RTP interval. There were no other consistently significant effects, suggesting that high AD genetic risk is not strongly associated with more severe concussions or poor recovery in young adults. Future studies should attempt to replicate these findings in larger samples with longer follow-up using PRS calculated from diverse populations.

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.

Differences in Injury Profiles Between Female and Male Athletes Across the Participant Classification Framework: A Systematic Review and Meta-Analysis

BACKGROUND

Female sex is a significant determinant of anterior cruciate ligament (ACL) injury. It is not understood if sex is a key determinant of other sports-related injuries.

OBJECTIVE

The aim of this systematic review was to identify where differences in injury profiles are most apparent between the sexes in all sports across the six-tiered participant classification framework.

METHODS

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and the 'implementing PRISMA in Exercise, Rehabilitation, Sport medicine and SporTs science'(PERSiST) guidance. The databases PubMed, CINAHL, Web of Science, SPORTDiscus, Medline, Scopus, Cochrane Library and EBSCO were searched from database inception to 24 April 2023. Longitudinal, prospective and retrospective cohort studies and cross-sectional and descriptive epidemiology studies that used standard injury data collection were included. Studies were excluded if injuries were not medically diagnosed and if injuries were not reported and/or analysed by sex. Two reviewers independently extracted data and assessed study quality using the Downs and Black checklist.

RESULTS

Overall, 180 studies were included (8 tier-5, 40 tier-4, 98 tier-3, 30 tier-2, 5 tier-1 studies; one study included data in two tiers). Of those, 174 studies were of moderate quality and six studies were of limited quality. In sex-comparable sports, there was moderate evidence that female athletes had greater risk of knee injury (relative risk (RR) 2.7; 95% CI 1.4-5.5), foot/ankle injuries (RR 1.25; 95% CI 1.17-1.34), bone stress injury (RR 3.4; 95% CI 2.1-5.4) and concussion (RR 8.46; 95% CI 1.04-68.77) than male athletes. Male athletes were at increased risk of hip/groin injuries (RR 2.26; 95% CI 1.31-3.88) and hamstring injuries (RR 2.4; 95% CI 1.8-3.2) compared with females, particularly in dynamic sports. Male athletes were 1.8 (1.37-2.7) to 2.8 (2.45-3.24) times more likely to sustain acute fractures than female athletes, with the highest risk in competition.

DISCUSSION

Most studies in all cohorts were of moderate quality (mean/range of scores tier-5: 17 ± 2.2 [14-20], tier-4: 16.9 ± 1.9 [11-21], tier-3: 16.9 ± 1.5 [11-20], tier-2: 16.3 ± 2.2 [11-20], tier-1 studies: 15.6 ± 1.3 [14-17] out of 28 on the Downs and Black checklist), with only six studies of limited quality. Female athletes' propensity for bone stress injuries highlights opportunities to reinforce development of optimal bone health during adolescence and to outline the effects of energy availability. Earlier strength development and exposure to neuromuscular training programmes and modification of skill development in female athletes may be effective strategies for reducing lower limb injury risk. Key components of neuromuscular training programmes could be beneficial for reducing hip/groin and hamstring injury risk in male athletes. There may be a need for sex-specific prevention and return-to-sport protocols for sports-related concussion in female athletes.

CONCLUSIONS

Female sex was a key determinant of sports-related injuries beyond ACL injury including foot/ankle injury, bone stress injury and sports-related concussion. Male sex was a key determinant of hip/groin, hamstring injury and upper limb injury.

TRIAL REGISTRY

PROSPERO registration number: CRD42017058806 (last updated on 7th June 2023).

Cause of Concussion With Persisting Symptoms Is Associated With Long-Term Recovery and Symptom Type, Duration, and Number in a Longitudinal Cohort of 600 Patients

It is important for patients and clinicians to know the potential for recovery from concussion as soon as possible after injury, especially in patients who do not recover completely in the first month and have concussion with persisting concussion symptoms (C+PCS). We assessed the association between the causes of concussion and recovery from C+PCS in a consecutive retrospective and prospective cohort of 600 patients referred to the Canadian Concussion Center (CCC) at Toronto Western Hospital. Data were obtained from clinical records and follow-up questionnaires and not from a standardized database. A novel method was used to assess long-term recovery, and multi-variable Cox proportional hazards models were used to assess relationships between cause of concussion and time to recovery. We examined the subsequent recovery of patients who had not recovered after at least one month from the time of concussion. Patients were grouped into the following four causes: sports and recreation (S&R, n = 312, 52%); motor vehicle collisions (MVC, n = 103, 17%); falls (n = 100, 17%); and being struck by an object including violence (SBOV, n = 85, 14%). The MVC group had the highest percentage of females (75.7%), the oldest participants (median: 40.0 [interquartile range (IQR):30.5-49.0] years), the most symptoms (median:11.0 [IQR:8.5-15.0]), and the longest symptom duration (median: 28.0 [IQR:12.0-56.00] months). In contrast, the S&R group had the highest percentage of males (58.1%), the youngest participants (median:20.0 [IQR:17.0-30.0] years), the best recovery outcome, and shortest symptom duration (median:22.0 [IQR:8.0-49.5] months). Significant differences among the four causes included age (p < 0.001), sex (p < 0.001), number of previous concussions (p < 0.001), history of psychiatric disorders (p = 0.002), and migraine (p = 0.001). Recovery from concussion was categorized into three groups: (1) Complete Recovery occurred in only 60 (10%) patients with median time 8.0 (IQR:3.5-18.0) months and included 42 S&R, 7 MVC, 8 falls, and 3 SBOV; (2) Incomplete Recovery occurred in 408 (68.0%) patients with persisting median symptom time of 5.0 (IQR:2.0-12.0) months; and (3) Unknown Recovery occurred in 132 (22.0%) patients and was because of lack of follow-up. In summary, the cause of C+PCS was associated with the type, number, and duration of symptoms and time required for recovery, although all causes of C+PCS produced prolonged symptoms in a large percentage of patients, which emphasizes the importance of concussions as a public health concern necessitating improved prevention and treatment strategies.

Sex differences in the extent of acute axonal pathologies after experimental concussion

Although human females appear be at a higher risk of concussion and suffer worse outcomes than males, underlying mechanisms remain unclear. With increasing recognition that damage to white matter axons is a key pathologic substrate of concussion, we used a clinically relevant swine model of concussion to explore potential sex differences in the extent of axonal pathologies. At 24 h post-injury, female swine displayed a greater number of swollen axonal profiles and more widespread loss of axonal sodium channels than males. Axon degeneration for both sexes appeared to be related to individual axon architecture, reflected by a selective loss of small caliber axons after concussion. However, female brains had a higher percentage of small caliber axons, leading to more extensive axon loss after injury compared to males. Accordingly, sexual dimorphism in axonal size is associated with more extensive axonal pathology in females after concussion, which may contribute to worse outcomes.

Mechanisms of Injury Leading to Concussions in Collegiate Soccer Players: A CARE Consortium Study

BACKGROUND

Few previous studies have investigated how different injury mechanisms leading to sport-related concussion (SRC) in soccer may affect outcomes.

PURPOSE

To describe injury mechanisms and evaluate injury mechanisms as predictors of symptom severity, return to play (RTP) initiation, and unrestricted RTP (URTP) in a cohort of collegiate soccer players.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The Concussion Assessment, Research and Education (CARE) Consortium database was used. The mechanism of injury was categorized into head-to-ball, head-to-head, head-to-body, and head-to-ground/equipment. Baseline/acute injury characteristics-including Sports Concussion Assessment Tool-3 total symptom severity (TSS), loss of consciousness (LOC), and altered mental status (AMS); descriptive data; and recovery (RTP and URTP)-were compared. Multivariable regression and Weibull models were used to assess the predictive value of the mechanism of injury on TSS and RTP/URTP, respectively.

RESULTS

Among 391 soccer SRCs, 32.7% were attributed to a head-to-ball mechanism, 27.9% to a head-to-body mechanism, 21.7% to a head-to-head mechanism, and 17.6% to a head-to-ground/equipment mechanism. Event type was significantly associated with injury mechanism [χ2(3) = 63; P < .001), such that more head-to-ball concussions occurred in practice sessions (n = 92 [51.1%] vs n = 36 [17.1%]) and more head-to-head (n = 65 [30.8%] vs n = 20 [11.1]) and head-to-body (n = 76 [36%] vs n = 33 [18.3%]) concussions occurred in competition. The primary position was significantly associated with injury mechanism [χ2(3) = 24; P < .004], with goalkeepers having no SRCs from the head-to-head mechanism (n = 0 [0%]) and forward players having the least head-to-body mechanism (n = 15 [19.2%]). LOC was also associated with injury mechanism (P = .034), with LOC being most prevalent in head-to-ground/equipment. Finally, AMS was most prevalent in head-to-ball (n = 54 [34.2%]) and head-to-body (n = 48 [30.4%]) mechanisms [χ2(3) = 9; P = .029]. In our multivariable models, the mechanism was not a predictor of TSS or RTP; however, it was associated with URTP (P = .044), with head-to-equipment/ground injuries resulting in the shortest mean number of days (14 ± 9.1 days) to URTP and the head-to-ball mechanism the longest (18.6 ± 21.6 days).

CONCLUSION

The mechanism of injury differed by event type and primary position, and LOC and AMS were different across mechanisms. Even though the mechanism of injury was not a significant predictor of acute symptom burden or time until RTP initiation, those with head-to-equipment/ground injuries spent the shortest time until URTP, and those with head-to-ball injuries had the longest time until URTP.

ENIGMA's simple seven: Recommendations to enhance the reproducibility of resting-state fMRI in traumatic brain injury

Resting state functional magnetic resonance imaging (rsfMRI) provides researchers and clinicians with a powerful tool to examine functional connectivity across large-scale brain networks, with ever-increasing applications to the study of neurological disorders, such as traumatic brain injury (TBI). While rsfMRI holds unparalleled promise in systems neurosciences, its acquisition and analytical methodology across research groups is variable, resulting in a literature that is challenging to integrate and interpret. The focus of this narrative review is to address the primary methodological issues including investigator decision points in the application of rsfMRI to study the consequences of TBI. As part of the ENIGMA Brain Injury working group, we have collaborated to identify a minimum set of recommendations that are designed to produce results that are reliable, harmonizable, and reproducible for the TBI imaging research community. Part one of this review provides the results of a literature search of current rsfMRI studies of TBI, highlighting key design considerations and data processing pipelines. Part two outlines seven data acquisition, processing, and analysis recommendations with the goal of maximizing study reliability and between-site comparability, while preserving investigator autonomy. Part three summarizes new directions and opportunities for future rsfMRI studies in TBI patients. The goal is to galvanize the TBI community to gain consensus for a set of rigorous and reproducible methods, and to increase analytical transparency and data sharing to address the reproducibility crisis in the field.

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.

Characterizing the profiles of patients with acute concussion versus prolonged post-concussion symptoms in Ontario

Identifying vulnerability factors for developing persisting concussion symptoms is imperative for determining which patients may require specialized treatment. Using cross-sectional questionnaire data from an Ontario-wide observational concussion study, we compared patients with acute concussion (≤ 14 days) and prolonged post-concussion symptoms (PPCS) (≥ 90 days) on four factors of interest: sex, history of mental health disorders, history of headaches/migraines, and past concussions. Differences in profile between the two groups were also explored. 110 patients with acute concussion and 96 patients with PPCS were included in our study. The groups did not differ on the four factors of interest. Interestingly, both groups had greater proportions of females (acute concussion: 61.1% F; PPCS: 66.3% F). Patient profiles, however, differed wherein patients with PPCS were significantly older, more symptomatic, more likely to have been injured in a transportation-related incident, and more likely to live outside a Metropolitan city. These novel risk factors for persisting concussion symptoms require replication and highlight the need to re-evaluate previously identified risk factors as more and more concussions occur in non-athletes and different risk factors may be at play.

Making the case for prophylactic use of betaine to promote brain health in young (15-24 year old) athletes at risk for concussion

Betaine supplementation in the context of human nutrition, athletic performance, and clinical therapy demonstrate that the osmolyte and methyl donor, betaine, is cytoprotective and beneficial to human health. These studies also demonstrate that betaine supplementation in healthy humans is straight-forward with no reported adverse effects. Here, we explore betaine uptake in the central nervous system (CNS) and contribute to evidence that betaine may be uniquely protective to the brain. We specifically describe the therapeutic potential of betaine and explore the potential implications of betaine on inhibition mediated by GABA and glycine neurotransmission. The influence of betaine on neurophysiology complement betaine's role as an osmolyte and metabolite and is consistent with clinical evidence of betaine-mediated improvements to cognitive function (reported in elderly populations) and its anti-convulsant properties. Betaine's therapeutic potential in neurological disorders including epilepsy and neurodegenerative diseases combined with benefits of betaine supplementation on athletic performance support the unique application of betaine as a prophylaxis to concussion. As an example, we identify young athletes (15-24 years old), especially females, for prophylactic betaine supplementation to promote brain health and resilience in a cohort at high risk for concussion and for developing Alzheimer's disease.

Health problems occurring in national-level female soccer players are different between leagues and throughout the season: a 6-month prospective cohort study

Objectives

This study investigated the prevalence and severity of health problems in national-level female soccer players with respect to league and seasonality.

Methods

In a prospective cohort study, 46 female soccer players aged 22.8±3.9 years playing in the three highest leagues in Switzerland were surveyed biweekly using the Oslo Sports Trauma Research Centre health problem (OSTRC-H) questionnaire. All definitions and measures followed the OSTRC-H-specific recommendations. The 6-month observation period included parts of the off-season and one half of the match season.

Results

The average 2-weekly health problem prevalence was 37.3% (illnesses: 8.8%; sudden onset injuries-both acute and repetitive mechanisms: 19.7%; repetitive gradual onset injuries: 12.4%) and 25.1% for substantial problems as defined in the OSTRC-H context (7.3%; 12.0% and 7.3%, respectively). The absolute injury rates amounted to 148 injuries per 100 players per half season, of which 96 injuries per 100 players per half season were substantial. Female players in the 2nd and 3rd highest national leagues showed more gradual onset injuries (p<0.001) and fewer illnesses than those in the top league (p<0.05). At the same time, there were no league-specific differences in sudden onset injuries. Such injuries had a higher cumulative severity score than gradual onset injuries. Among sudden onset injuries, the ankle was the most affected body part, while the thigh was affected by for gradual onset injuries. The average 2-weekly health problem prevalence values steadily increased during the match season.

Conclusion

Among national-level female soccer players, the risk of health problems is relatively high and differs between leagues and across seasons.

A case-control study of tackle based head impact event (HIE) risk factors from the first three seasons of the National Rugby League Women's competition

Objective

The tackle is the most injurious event in rugby league and carries the greatest risk of concussion. This study aims to replicate previous research conducted in professional men's rugby league by examining the association between selected tackle characteristics and head impact events (HIEs) in women's professional rugby league.

Methods

We reviewed and coded 83 tackles resulting in an HIE and every tackle (6,318 tackles) that did not result in an HIE for three seasons (2018-2020) of the National Rugby League Women's (NRLW) competition. Tackle height, body position of the tackler and ball carrier, as well as the location of head contact with the other player's body were evaluated. Propensity of each situation that caused an HIE was calculated as HIEs per 1,000 tackles.

Results

The propensity for tacklers to sustain an HIE was 6.60 per 1,000 tackles (95% CI: 4.87-8.92), similar to that of the ball carrier (6.13 per 1,000 tackles, 95% CI: 4.48-8.38). The greatest risk of an HIE to either the tackler or ball carrier occurred when head proximity was above the sternum (21.66 per 1,000 tackles, 95% CI: 16.55-28.35). HIEs were most common following impacts between two heads (287.23 HIEs per 1,000 tackles, 95% CI: 196.98-418.84). The lowest propensity for both tackler (2.65 per 1,000 tackles, 95% CI: 0.85-8.20) and ball carrier HIEs (1.77 per 1,000 tackles, 95% CI: 0.44-7.06) occurred when the head was in proximity to the opponent's shoulder and arm. No body position (upright, bent or unbalanced/off feet) was associated with an increased propensity of HIE to either tackler or ball carrier.

Conclusions

In the NRLW competition, tacklers and ball carriers have a similar risk of sustaining an HIE during a tackle, differing from men's NRL players, where tacklers have a higher risk of HIEs. Further studies involving larger samples need to validate these findings. However, our results indicate that injury prevention initiatives in women's rugby league should focus on how the ball carrier engages in contact during the tackle as well as how the tackler executes the tackle.

Factors related to adverse long-term outcomes after mild traumatic brain injury in children: a scoping review

OBJECTIVE

To identify demographic, premorbid and injury-related factors, or biomarkers associated with long-term (≥3 months) adverse outcomes in children after mild traumatic brain injury (mTBI).

DESIGN

Scoping review of literature.

PATIENTS

Children and adolescents with mTBI.

RISK FACTORS

Any demographic, premorbid and injury-related factors, or biomarkers were included. We excluded genetic and treatment-related factors.

MAIN OUTCOME MEASURES

Postconcussion syndrome (PCS), recovery.

RESULTS

Seventy-three publications were included, reporting 12 long-term adverse outcomes, including PCS in 12 studies and recovery in 29 studies. Additional outcomes studied were symptom scores/severity (n=22), quality of life (n=9) and cognitive function (n=9). Forty-nine risk factors were identified across studies. Risk factors most often assessed were sex (n=28), followed by age (n=23), injury mechanism = (n=22) and prior mTBI (n=18). The influence of these and other risk factors on outcomes of mTBI were inconsistent across the reviewed literature.

CONCLUSIONS

The most researched risk factors are sex, age and mechanism of injury, but their effects have been estimated inconsistently and did not show a clear pattern. The most studied outcomes are recovery patterns and symptom severity. However, these may not be the most important outcomes for clinicians and patients. Future primary studies in this area should focus on patient-important outcomes. Population-based prospective studies are needed that address prespecified hypotheses on the relationship of risk factors with given outcomes to enable reliable prediction of long-term adverse outcomes for childhood mTBI.

Median Time to Return to Sports After Concussion Is Within 21 Days in 80% of Published Studies

PURPOSE

To perform a systematic review of the literature and evaluate the return to play (RTP) time frame after a concussion diagnosis. Our secondary purpose was to analyze and compare different prognostic variables affecting concussions, time to return to school, time to symptom resolution of concussive symptoms, and time each patient spent in the RTP protocol.

METHODS

A PubMed, Scopus, Medline, Embase, and Cochrane Library database literature review was performed in August 2022. The studies needed to report, in days, the length of time a patient/athlete was removed from play due to concussion management. The Risk of Bias in Non-Randomized Studies of Interventions tool was used for risk of bias for each study, and Methodological Index for Non-Randomized Studies criteria were used for quality assessment.

RESULTS

There were 65 studies included in the systematic review and a total of 21,966 patients evaluated. The RTP time intervals ranged from 1 to 1,820 days, with 80.7% of the median RTP time frames for each study within 21 days. Preconcussion risk factors for prolonged RTP included female sex, younger age, presence of psychiatric disorders, and history of previous concussion. Postconcussion risk factors included severe symptom scores at initial clinic visit, loss of consciousness, nonelite athletes, and delayed removal from competition. The most common sports resulting in concussion were contact sports, most commonly football and soccer. Median time to return to school was 3 to 23 days. Median time to symptom resolution ranged from 2 to 11 days. Median time in RTP protocol was 1 to 6 days.

CONCLUSIONS

Median time to return to sports after concussion is within 21 days in 80% of published studies.

LEVEL OF EVIDENCE

IV, systematic review of Level I to IV studies.

Cognitive and Behavioral Outcomes in Male and Female NCAA Soccer Athletes across Multiple Years: A CARE Consortium Study

PURPOSE

The purpose of this study was to determine changes in neurocognitive, psychosocial, and balance functioning in collegiate male and female soccer players across three consecutive years of baseline testing compared with a control group of noncontact athletes.

METHODS

Generalized estimating equations were used to compare changes in annual, preseason baseline measures of neurocognitive function, neurobehavioral and psychological symptoms, and postural stability between collegiate soccer players ( n = 75; 51 [68%] female soccer players) and noncontact athletes ( n = 210; 133 [63%] female noncontact athletes) across three consecutive years.

RESULTS

Among all participants, the group-time interaction was not significant for any outcome measures. Overall, soccer players reported lower (better) Brief Symptom Inventory 18 Depression ( P = 0.004, Exp(B) = 0.36, 95% confidence interval [CI] = 0.18-0.73), Global Severity Index ( P = 0.006, Exp(B) = 0.53, 95% CI = 0.33-0.84), and Post-Concussion Symptom Scale Symptom Severity ( P < 0.001, Exp(B) = 0.45, 95% CI = 0.22-0.95) scores than noncontact athletes. No other outcome measures were different between soccer players and noncontact athletes.

CONCLUSIONS

Among collegiate athletes, soccer players report similar or better psychosocial functioning and symptom scores than noncontact athletes. Importantly, neurocognitive functioning, neurobehavioral and psychological symptoms, and postural stability do not worsen over time in collegiate soccer players relative to their noncontact counterparts. Our findings suggest that despite possible exposure to repetitive head impacts, collegiate soccer players do not exhibit changes in observable function and symptoms across multiple seasons.

Efficacy of aerobic exercise following concussion: a narrative review

Concussion is a type of mild traumatic brain injury which results in symptoms within the physical, cognitive, emotional, and sleep domains. Historically, guidelines established by expert opinion have recommended rest during the initial stages of recovery following a concussion until symptom resolution. However, recent recommendations have shifted to advise an initial period of 24-48 h of rest immediately following concussion with the gradual introduction of light-to-moderate intensity aerobic exercise thereafter. Given the relatively recent transition in recommendations, the aim of this review is to provide an overview of the current literature on the efficacy of aerobic exercise following concussion. The current literature is limited to studies assessing the impact of standardized aerobic exercise following concussion. Upon review, literature suggests participating in aerobic exercise below the point of symptom exacerbation is safe in both the acute and chronic post-concussion symptom stages of recovery and does not delay time to medical clearance. Future large-scale randomized controlled trials assessing the impact of aerobic exercise and differences between males and females would help support the current evidence suggesting aerobic exercise could improve time to recovery following concussion and identify any sex differences in response. As well, future studies with the purpose of identifying optimal aerobic exercise volume and intensity in the treatment of concussion could improve the specificity of the current guidelines.

The incidence and burden of injuries in elite English youth female soccer players

This study aimed to investigate the incidence, severity and burden of injury in English elite youth female soccer players. Qualified therapists at six English girls' academies prospectively recorded all injuries that required medical attention or caused time loss for matches and training in 375 elite youth female soccer players (under-10 [U10], U12, U14 and U16) during the 2019/2020 season. One hundred- and eleven time-loss injuries (52 from training, 59 from matches) were sustained, resulting in 1,946 days absent (779 days from training injuries, 1,167 days from match injuries) from soccer activities. The injury incidence for matches (9.3/1000 hours, 95% CIs: 7.2-11.9) was significantly greater than training (1.1/1000 hours, 95% CIs: 0.9-1.5, p < 0.001). Additionally, the injury burden for matches (183 days lost/1000 hours, 95% CIs: 142-237) was significantly greater than training (17 days lost/1000 hours, 95% CIs: 13-22, p < 0.001). Injury incidence and burden were greatest in the U16 age group and were found to increase with age. Whilst injury incidence and burden are greater in matches than training, a large proportion of preventable injuries, soft-tissue and non-contact in nature, were sustained in training. Findings provide comparative data for elite youth female soccer players.

Complicity: Methodologies of power, politics and the ethics of knowledge production

In this collection we develop the concept of "complicity" as a means to understand how medical sociologists might be allied in unexpected or uncomfortable ways with dominant structures of power. After giving examples of complicity from our own research, we introduce existing scholarship on complicity, describing it as a concept that comes coupled with a sense of responsibility and that is related to, yet distinct from, a range of other terms including reflexivity, collusion, guilt, and shame. We also discuss how complicity has been described to occur at the level of the institution, within theoretical frameworks, and during mundane moments that we face on a day-to-day basis. Building on this review, we hypothesise that medical sociology - where access to fieldsites is often hard won, where "researching up" in medical and scientific institutions is common, and where our own work frequently concerns matters central to medical institutions themselves - is a discipline wherein mundane complicity is likely. Following this gathering exercise, we introduce the interventions that comprise this collection: interventions from a diversity of sociologists of health and illness who, perhaps for the first time in written form, account for how complicities of various kinds came to shape their work and how, with varying levels of success, they have sought redress. We close by offering some insight into the process of developing this collection, celebrating its successes while also acknowledging that many gaps and complicities remain.

Traumatic brain injury: progress and challenges in prevention, clinical care, and research

Traumatic brain injury (TBI) has the highest incidence of all common neurological disorders, and poses a substantial public health burden. TBI is increasingly documented not only as an acute condition but also as a chronic disease with long-term consequences, including an increased risk of late-onset neurodegeneration. The first Lancet Neurology Commission on TBI, published in 2017, called for a concerted effort to tackle the global health problem posed by TBI. Since then, funding agencies have supported research both in high-income countries (HICs) and in low-income and middle-income countries (LMICs). In November 2020, the World Health Assembly, the decision-making body of WHO, passed resolution WHA73.10 for global actions on epilepsy and other neurological disorders, and WHO launched the Decade for Action on Road Safety plan in 2021. New knowledge has been generated by large observational studies, including those conducted under the umbrella of the International Traumatic Brain Injury Research (InTBIR) initiative, established as a collaboration of funding agencies in 2011. InTBIR has also provided a huge stimulus to collaborative research in TBI and has facilitated participation of global partners. The return on investment has been high, but many needs of patients with TBI remain unaddressed. This update to the 2017 Commission presents advances and discusses persisting and new challenges in prevention, clinical care, and research.

In LMICs, the occurrence of TBI is driven by road traffic incidents, often involving vulnerable road users such as motorcyclists and pedestrians. In HICs, most TBI is caused by falls, particularly in older people (aged ≥65 years), who often have comorbidities. Risk factors such as frailty and alcohol misuse provide opportunities for targeted prevention actions. Little evidence exists to inform treatment of older patients, who have been commonly excluded from past clinical trials—consequently, appropriate evidence is urgently required. Although increasing age is associated with worse outcomes from TBI, age should not dictate limitations in therapy. However, patients injured by low-energy falls (who are mostly older people) are about 50% less likely to receive critical care or emergency interventions, compared with those injured by high-energy mechanisms, such as road traffic incidents.

Mild TBI, defined as a Glasgow Coma sum score of 13–15, comprises most of the TBI cases (over 90%) presenting to hospital. Around 50% of adult patients with mild TBI presenting to hospital do not recover to pre-TBI levels of health by 6 months after their injury. Fewer than 10% of patients discharged after presenting to an emergency department for TBI in Europe currently receive follow-up. Structured follow-up after mild TBI should be considered good practice, and urgent research is needed to identify which patients with mild TBI are at risk for incomplete recovery.

The selection of patients for CT is an important triage decision in mild TBI since it allows early identification of lesions that can trigger hospital admission or life-saving surgery. Current decision making for deciding on CT is inefficient, with 90–95% of scanned patients showing no intracranial injury but being subjected to radiation risks. InTBIR studies have shown that measurement of blood-based biomarkers adds value to previously proposed clinical decision rules, holding the potential to improve efficiency while reducing radiation exposure. Increased concentrations of biomarkers in the blood of patients with a normal presentation CT scan suggest structural brain damage, which is seen on MR scanning in up to 30% of patients with mild TBI. Advanced MRI, including diffusion tensor imaging and volumetric analyses, can identify additional injuries not detectable by visual inspection of standard clinical MR images. Thus, the absence of CT abnormalities does not exclude structural damage—an observation relevant to litigation procedures, to management of mild TBI, and when CT scans are insufficient to explain the severity of the clinical condition.

Although blood-based protein biomarkers have been shown to have important roles in the evaluation of TBI, most available assays are for research use only. To date, there is only one vendor of such assays with regulatory clearance in Europe and the USA with an indication to rule out the need for CT imaging for patients with suspected TBI. Regulatory clearance is provided for a combination of biomarkers, although evidence is accumulating that a single biomarker can perform as well as a combination. Additional biomarkers and more clinical-use platforms are on the horizon, but cross-platform harmonisation of results is needed. Health-care efficiency would benefit from diversity in providers.

In the intensive care setting, automated analysis of blood pressure and intracranial pressure with calculation of derived parameters can help individualise management of TBI. Interest in the identification of subgroups of patients who might benefit more from some specific therapeutic approaches than others represents a welcome shift towards precision medicine. Comparative-effectiveness research to identify best practice has delivered on expectations for providing evidence in support of best practices, both in adult and paediatric patients with TBI.

Progress has also been made in improving outcome assessment after TBI. Key instruments have been translated into up to 20 languages and linguistically validated, and are now internationally available for clinical and research use. TBI affects multiple domains of functioning, and outcomes are affected by personal characteristics and life-course events, consistent with a multifactorial bio-psycho-socio-ecological model of TBI, as presented in the US National Academies of Sciences, Engineering, and Medicine (NASEM) 2022 report. Multidimensional assessment is desirable and might be best based on measurement of global functional impairment. More work is required to develop and implement recommendations for multidimensional assessment. Prediction of outcome is relevant to patients and their families, and can facilitate the benchmarking of quality of care. InTBIR studies have identified new building blocks (eg, blood biomarkers and quantitative CT analysis) to refine existing prognostic models. Further improvement in prognostication could come from MRI, genetics, and the integration of dynamic changes in patient status after presentation.

Neurotrauma researchers traditionally seek translation of their research findings through publications, clinical guidelines, and industry collaborations. However, to effectively impact clinical care and outcome, interactions are also needed with research funders, regulators, and policy makers, and partnership with patient organisations. Such interactions are increasingly taking place, with exemplars including interactions with the All Party Parliamentary Group on Acquired Brain Injury in the UK, the production of the NASEM report in the USA, and interactions with the US Food and Drug Administration. More interactions should be encouraged, and future discussions with regulators should include debates around consent from patients with acute mental incapacity and data sharing. Data sharing is strongly advocated by funding agencies. From January 2023, the US National Institutes of Health will require upload of research data into public repositories, but the EU requires data controllers to safeguard data security and privacy regulation. The tension between open data-sharing and adherence to privacy regulation could be resolved by cross-dataset analyses on federated platforms, with the data remaining at their original safe location. Tools already exist for conventional statistical analyses on federated platforms, however federated machine learning requires further development. Support for further development of federated platforms, and neuroinformatics more generally, should be a priority.

This update to the 2017 Commission presents new insights and challenges across a range of topics around TBI: epidemiology and prevention (section 1 ); system of care (section 2 ); clinical management (section 3 ); characterisation of TBI (section 4 ); outcome assessment (section 5 ); prognosis (Section 6 ); and new directions for acquiring and implementing evidence (section 7 ). Table 1 summarises key messages from this Commission and proposes recommendations for the way forward to advance research and clinical management of TBI.

Traumatic brain injury recapitulates developmental changes of axons

During development, half of brain white matter axons are maintained for growth, while the remainder undergo developmental axon degeneration. After traumatic brain injury (TBI), injured axons also appear to follow pathways leading to either degeneration or repair. These observations raise the intriguing, but unexamined possibility that TBI recapitulates developmental axonal programs. Here, we examined axonal changes in the developing brain in young rats and after TBI in adult rat. Multiple shared changes in axonal microtubule (MT) through tubulin post-translational modifications and MT associated proteins (MAPs), tau and MAP6, were found in both development and TBI. Specifically, degenerating axons in both development and TBI underwent phosphorylation of tau and excessive tubulin tyrosination, suggesting MT instability and depolyermization. Conversely, nearby axons without degenerating morphologies, had increased MAP6 expression and maintenance of tubulin acetylation, suggesting enhanced MT stabilization, thereby supporting survival or repair. Quantitative proteomics revealed similar signaling pathways of axon degeneration and growth/repair, including protein clusters and networks. This comparison approach demonstrates how focused evaluation of developmental processes may provide insight into pathways initiated by TBI. In particular, the data suggest that TBI may reawaken dormant axonal programs that direct axons towards either degeneration or growth/repair, supporting further study in this area.

Brain architecture-based vulnerability to traumatic injury

The white matter tracts forming the intricate wiring of the brain are subject-specific; this heterogeneity can complicate studies of brain function and disease. Here we collapse tractography data from the Human Connectome Project (HCP) into structural connectivity (SC) matrices and identify groups of similarly wired brains from both sexes. To characterize the significance of these architectural groupings, we examined how similarly wired brains led to distinct groupings of neural activity dynamics estimated with Kuramoto oscillator models (KMs). We then lesioned our networks to simulate traumatic brain injury (TBI) and finally we tested whether these distinct architecture groups’ dynamics exhibited differing responses to simulated TBI. At each of these levels we found that brain structure, simulated dynamics, and injury susceptibility were all related to brain grouping. We found four primary brain architecture groupings (two male and two female), with similar architectures appearing across both sexes. Among these groupings of brain structure, two architecture types were significantly more vulnerable than the remaining two architecture types to lesions. These groups suggest that mesoscale brain architecture types exist, and these architectural differences may contribute to differential risks to TBI and clinical outcomes across the population.

The Role of Reported Affective Symptoms and Anxiety in Recovery Trajectories After Sport-Related Concussion

BACKGROUND

There is growing awareness and clinical interest in athletes with affective symptoms after sport-related concussion (SRC), as these symptoms may contribute to overall symptoms and represent a modifiable risk factor of longer recovery. However, evidence of their effects on the entire return-to-play (RTP) trajectory, particularly among women and men, is limited.

PURPOSE/HYPOTHESIS

To examine the relationship between affective symptom reporting and RTP progression after SRC among a cohort of Division 1 student-athletes. We hypothesized that those endorsing affective symptoms, specifically nervous-anxious symptoms, spend more time in RTP progression and recovery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Using SRC data from the Ivy League-Big Ten Epidemiology of Concussion Study among varsity athletes through February 2020, we identified the 4 affective symptoms from the Sport Concussion Assessment Tool symptom inventory. We modeled the relationship between a 4-category affective symptom variable and time to symptom resolution, RTP, and RTP progression, adjusting for nonaffective symptom prevalence and concussion history. Cox regressions were used to estimate hazard ratios for time to event outcomes, and linear regressions were used to evaluate mean differences for continuous outcomes.

RESULTS

Among 2077 student-athletes (men, 63.5%) with SRC symptoms, affective symptom prevalence was 47.6% and 44.3% in women and men, respectively, and nervous-anxious prevalence was 24.2% and 22.5%, respectively. When comparing women with and without co-occurring affective symptoms, rates of symptom resolution and RTP were significantly lower in those with affective symptoms, and women with nervous-anxious symptoms spent significantly longer in RTP progression. When comparing men with and without co-occurring affective symptoms, rates of symptom resolution and RTP were significantly lower in those with co-occurring affective symptoms, and affective symptoms were not associated with time in RTP progression.

CONCLUSION

Student-athletes with affective symptoms and nervous-anxious symptoms exhibited delayed clinical recovery and RTP timelines, particularly for time in RTP. Symptom prevalence and concussion history contributed to this; however, unmeasured confounding remains, as indicated by the poor model fit. This study motivates future work to explore affective symptoms and RTP timelines, considering anxiety and risk/protective factors over time.

Concussion Nondisclosure in Youth Sports

CONTEXT

Researchers conducting studies about sport-related concussion (SRC) reporting behaviors and reasons for nondisclosure primarily focus on older athletic populations. Youth athletes participating in contact sports are also at risk for SRC; however, little is known about their SRC disclosure patterns and reasons for nondisclosure.

OBJECTIVE

To examine the self-reported SRC history and reasons for SRC nondisclosure of youth athletes aged 8-14 years.

DESIGN

Cross-sectional study.

SETTING

Youth athletes in organized football, ice hockey, lacrosse, or soccer.

PATIENTS OR OTHER PARTICIPANTS

A total of 411 youth athletes (boys = 70.0% [n = 287/410]; median age = 11 [interquartile range = 10-13] years).

MAIN OUTCOME MEASURE(S)

A 15-minute survey including self-reported demographics, diagnosed and nondisclosed SRC history, and reasons for nondisclosure of suspected SRCs.

RESULTS

Ten percent of respondents (n = 41/411) recounted ≥1 diagnosed SRC, 12.7% (n = 52/411) did not report a suspected SRC, 13.1% (n = 53/404) indicated they continued to practice, and 12.3% (n = 50/406) reported they continued to play in a game after a suspected SRC. Significant associations between sport and nondisclosure existed (P values < .001) but not with self-reported concussion history (P = .14). In sex-comparable analyses, boys' lacrosse players had a higher frequency of nondisclosure than girls (P = .05). The most common reasons for nondisclosure were not wanting to lose playing time (66.7%, n = 32/48), miss a game (56.3%, n = 27/48), and let the team down (43.8%, n = 21/48) and uncertainty over injury severity and the presence of SRC (43.8%, n = 21/48).

CONCLUSIONS

Ten percent of youth athletes self-reported at least 1 diagnosed SRC. However, they also described continuing to practice or play in a game after a suspected SRC. Reasons for nondisclosure at this age were similar to those reported in high school and collegiate athletes. Recent researchers suggested negative consequences of continued play with SRC, especially in the acute stages. Anyone conducting future educational initiatives should emphasize these risks and focus on reasons why athletes of both sexes withhold reporting.

Health conditions among retired professional footballers: a scoping review

Objective

To conduct a scoping review providing an overview of the health conditions occuring in retired male and female professional footballers, with an emphasis on musculoskeletal, mental, neurocognitive, cardiovascular and reproductive health conditions.

Methods

In January 2022, a comprehensive systematic literature search in three databases (MEDLINE via PubMed, SPORTDiscus via EBSCOhost and EMBASE) was conducted for common health conditions among retired male and female professional footballers. Primary research studies (full text available online) which described the incidence or prevalence of a health condition (musculoskeletal, mental, neurocognitive, cardiovascular, reproductive) among retired male and female professional footballers were included for review. Case reports, qualitative research and grey literature were omitted.

Results

In total, 917 eligible articles were identified from the databases, with 41 meeting the eligibility criteria. Osteoarthritis of the hip, knee and ankle were found to be common among retired professional footballers. Mental health symptoms (eg, anxiety, depression) are experienced by retired male and female professional footballers. The incidence of neurocognitive disease appears to be higher among retired male professional footballers than among matched controls. There is very limited evidence examining the presence of health conditions in retired female professional footballers.

Conclusion

Osteoarthritis of the lower limb, musculoskeletal pain and mental health symptoms are common among retired professional footballers. Knowledge about the occurrence and timing of musculoskeletal, mental health and neurocognitive conditions among retired professional footballers can be used by a wide range of stakeholders to proactively intervene during and after a player's career to mitigate risk.

Association between single moderate to severe traumatic brain injury and long-term tauopathy in humans and preclinical animal models: a systematic narrative review of the literature

BACKGROUND

The initiation, anatomic pattern, and extent of tau spread in traumatic brain injury (TBI), and the mechanism by which TBI leads to long-term tau pathology, remain controversial. Some studies suggest that moderate to severe TBI is sufficient to promote tau pathology; however, others suggest that it is simply a consequence of aging. We therefore conducted a systematic narrative review of the literature addressing whether a single moderate to severe head injury leads to long-term development of tauopathy in both humans and animal models.

METHODS

Studies considered for inclusion in this review assessed a single moderate to severe TBI, assessed tau pathology at long-term timepoints post-injury, comprised experimental or observational studies, and were peer-reviewed and published in English. Databases searched included: PUBMED, NCBI-PMC, EMBASE, Web of Science, Academic Search Premiere, and APA Psychnet. Search results were uploaded to Covidence®, duplicates were removed, and articles underwent an abstract and full-text screening process. Data were then extracted and articles assessed for risk of bias.

FINDINGS

Of 4,150 studies screened, 26 were eligible for inclusion, of which 17 were human studies, 8 were preclinical animal studies, and 1 included both human and preclinical animal studies. Most studies had low to moderate risk of bias. Most human and animal studies (n = 12 and 9, respectively) suggested that a single moderate to severe TBI resulted in greater development of long-term tauopathy compared to no history of head injury. This conclusion should be interpreted with caution, however, due to several limitations: small sample sizes; inconsistencies in controlling for confounding factors that may have affected tau pathology (e.g., family history of dementia or neurological illnesses, apolipoprotein E genotype, etc.), inclusion of mostly males, and variation in reporting injury parameters.

INTERPRETATION

Results indicate that a single moderate to severe TBI leads to greater chronic development of tauopathy compared to no history of head injury. This implies that tau pathology induced may not be transient, but can progressively develop over time in both humans and animal models. Targeting these tau changes for therapeutic intervention should be further explored to elucidate if disease progression can be reversed or mitigated.

Traumatic brain injury in women across lifespan

Traumatic brain injury (TBI) is a leading cause of death and disability and a global public health challenge. Every year more than 50 million people suffer a TBI, and it is estimated that 50% of the global population will experience at least one TBI in their lifetime. TBI affects both men and women of all ages, however there is a male bias in TBI research as women have frequently been left out of the literature despite irrefutable evidence of male and female dimorphism in several posttraumatic measures. Women uniquely experience distinct life stages marked by levels of endogenous circulating sex hormones, as well as by physiological changes that are nonexistent in men. In addition to generalized sex-specific differences, a woman's susceptibility, neurological outcomes, and treatment success may vary considerably depending upon when in her lifespan she incurred a traumatic insult. How women impacted by TBI might differ from other women as a factor of age and physiology is not well understood. Furthermore, there is a gap in the knowledge of what happens when TBI occurs in the presence of certain sex-specific and sex-nonspecific variables, such as during pregnancy, with oral contraceptive use, in athletics, in cases of addiction and nicotine consumption, during perimenopause, postmenopause, in frailty, among others. Parsing out how hormone-dependent and hormone-independent lifespan variables may influence physiological, neurodegenerative, and functional outcomes will greatly contribute to future investigative studies and direct therapeutic strategies. The goal of this review is to aggregate the knowledge of prevalence, prognosis, comorbid risk, and response of women incurring TBI at differing phases of lifespan. We strive to illuminate commonalities and disparities among female populations, and to pose important questions to highlight gaps in the field in order to further the endeavor of targeted treatment interventions in a patient-specific manner.