Acute evaluation of sport-related concussion and implications for the Sport Concussion Assessment Tool (SCAT6) for adults, adolescents and children: a systematic review

OBJECTIVES

To systematically review the scientific literature regarding the acute assessment of sport-related concussion (SRC) and provide recommendations for improving the Sport Concussion Assessment Tool (SCAT6).

DATA SOURCES

Systematic searches of seven databases from 2001 to 2022 using key words and controlled vocabulary relevant to concussion, sports, SCAT, and acute evaluation.

ELIGIBILITY CRITERIA

(1) Original research articles, cohort studies, case-control studies, and case series with a sample of >10; (2) ≥80% SRC; and (3) studies using a screening tool/technology to assess SRC acutely (<7 days), and/or studies containing psychometric/normative data for common tools used to assess SRC.

DATA EXTRACTION

Separate reviews were conducted involving six subdomains: Cognition, Balance/Postural Stability, Oculomotor/Cervical/Vestibular, Emerging Technologies, and Neurological Examination/Autonomic Dysfunction. Paediatric/Child studies were included in each subdomain. Risk of Bias and study quality were rated by coauthors using a modified SIGN (Scottish Intercollegiate Guidelines Network) tool.

RESULTS

Out of 12 192 articles screened, 612 were included (189 normative data and 423 SRC assessment studies). Of these, 183 focused on cognition, 126 balance/postural stability, 76 oculomotor/cervical/vestibular, 142 emerging technologies, 13 neurological examination/autonomic dysfunction, and 23 paediatric/child SCAT. The SCAT discriminates between concussed and non-concussed athletes within 72 hours of injury with diminishing utility up to 7 days post injury. Ceiling effects were apparent on the 5-word list learning and concentration subtests. More challenging tests, including the 10-word list, were recommended. Test-retest data revealed limitations in temporal stability. Studies primarily originated in North America with scant data on children.

CONCLUSION

Support exists for using the SCAT within the acute phase of injury. Maximal utility occurs within the first 72 hours and then diminishes up to 7 days after injury. The SCAT has limited utility as a return to play tool beyond 7 days. Empirical data are limited in pre-adolescents, women, sport type, geographical and culturally diverse populations and para athletes.

PROSPERO REGISTRATION NUMBER

CRD42020154787.

Amsterdam 2022 process: A summary of the methodology for the Amsterdam International Consensus on Concussion in Sport

The purpose of this paper is to summarise the consensus methodology that was used to inform the International Consensus Statement on Concussion in Sport (Amsterdam 2022). Building on a Delphi process to inform the questions and outcomes from the 5th International Conference on Concussion in Sport, the Scientific Committee identified key questions, the answers to which would help encapsulate the current science in sport-related concussion and help guide clinical practice. Over 3½ years, delayed by 2 years due to the pandemic, author groups conducted systematic reviews on each selected topic. The 6th International Conference on Concussion in Sport was held in Amsterdam (27-30 October 2022) and consisted of 2 days of systematic review presentations, panel discussions, question and answer engagement with the 600 attendees, and abstract presentations. This was followed by a closed third day of consensus deliberations by an expert panel of 29 with observers in attendance. The fourth day, also closed, was dedicated to a workshop to discuss and refine the sports concussion tools (Concussion Recognition Tool 6 (CRT6), Sport Concussion Assessment Tool 6 (SCAT6), Child SCAT6, Sport Concussion Office Assessment Tool 6 (SCOAT6) and Child SCOAT6). We include a summary of recommendations for methodological improvements for future research that grew out of the systematic reviews.

Clinical recovery from concussion-return to school and sport: a systematic review and meta-analysis

OBJECTIVE

To define the time frames, measures used and modifying factors influencing recovery, return to school/learn (RTL) and return to sport (RTS) after sport-related concussion (SRC).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

8 databases searched through 22 March 2022.

ELIGIBILITY CRITERIA

Studies with diagnosed/suspected SRC and interventions facilitating RTL/RTS or investigating the time and modifying factors for clinical recovery. Outcomes included days until symptom free, days until RTL and days until RTS. We documented study design, population, methodology and results. Risk of bias was evaluated using a modified Scottish Intercollegiate Guidelines Network tool.

RESULTS

278 studies were included (80.6% cohort studies and 92.8% from North America). 7.9% were considered high-quality studies, while 23.0% were considered high risk of bias and inadmissible. The mean days until symptom free was 14.0 days (95% CI: 12.7, 15.4; I²=98.0%). The mean days until RTL was 8.3 (95% CI: 5.6, 11.1; I²=99.3%), with 93% of athletes having a full RTL by 10 days without new academic support. The mean days until RTS was 19.8 days (95% CI: 18.8, 20.7; I²=99.3%), with high heterogeneity between studies. Several measures define and track recovery, with initial symptom burden remaining the strongest predictor of longer days until RTS. Continuing to play and delayed access to healthcare providers were associated with longer recovery. Premorbid and postmorbid factors (eg, depression/anxiety, migraine history) may modify recovery time frames. Though point estimates suggest that female sex or younger age cohorts take longer to recover, the heterogeneity of study designs, outcomes and overlap in CIs with male sex or older age cohorts suggests that all have similar recovery patterns.

CONCLUSION

Most athletes have full RTL by 10 days but take twice as long for an RTS.

PROSPERO REGISTRATION NUMBER

CRD42020159928.

Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport-Amsterdam, October 2022

For over two decades, the Concussion in Sport Group has held meetings and developed five international statements on concussion in sport. This 6th statement summarises the processes and outcomes of the 6th International Conference on Concussion in Sport held in Amsterdam on 27-30 October 2022 and should be read in conjunction with the (1) methodology paper that outlines the consensus process in detail and (2) 10 systematic reviews that informed the conference outcomes. Over 3½ years, author groups conducted systematic reviews of predetermined priority topics relevant to concussion in sport. The format of the conference, expert panel meetings and workshops to revise or develop new clinical assessment tools, as described in the methodology paper, evolved from previous consensus meetings with several new components. Apart from this consensus statement, the conference process yielded revised tools including the Concussion Recognition Tool-6 (CRT6) and Sport Concussion Assessment Tool-6 (SCAT6, Child SCAT6), as well as a new tool, the Sport Concussion Office Assessment Tool-6 (SCOAT6, Child SCOAT6). This consensus process also integrated new features including a focus on the para athlete, the athlete's perspective, concussion-specific medical ethics and matters related to both athlete retirement and the potential long-term effects of SRC, including neurodegenerative disease. This statement summarises evidence-informed principles of concussion prevention, assessment and management, and emphasises those areas requiring more research.

Under-representation of female athletes in research informing influential concussion consensus and position statements: an evidence review and synthesis

OBJECTIVE

We aimed to quantify the female athlete composition of the research data informing the most influential consensus and position statements in treating sports-related concussions.

DESIGN

We identified the most influential concussion consensus and position statements through citation and documented clinician use; then, we analysed the percentage of male and female athletes from each statement's cited research.

DATA SOURCES

We searched PubMed on 26 August 2021 with no date restrictions for English language studies using the terms 'concussion position statement' and 'concussion consensus statement.'

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Based on each statement having multiple statement editions, documented clinician use, and substantial citation advantages, we selected the National Athletic Trainers' Association (NATA, 2014), International Conference on Concussion in Sport (ICCS, 2017) and the American Medical Society for Sports Medicine (AMSSM, 2019). We extracted all cited studies from all three papers for assessment. For each paper analysing human data, at least two authors independently recorded female athlete participant data.

RESULTS

A total of 171 distinct studies with human participants were cited by these three consensus and position papers and included in the female athlete analyses (93 NATA; 13 ICCS; 65 AMSSM). All three statements documented a significant under-representation of female athletes in their cited literature, relying on samples that were overall 80.1% male (NATA: 79.9%, ICCS: 87.8 %, AMSSM: 79.4%). Moreover, 40.4% of these studies include no female participants at all.

CONCLUSION

Female athletes are significantly under-represented in the studies guiding clinical care for sport-related concussion for a broad array of sports and exercise medicine clinicians. We recommend intentional recruitment and funding of gender diverse participants in concussion studies, suggest authorship teams reflect diverse perspectives, and encourage consensus statements note when cited data under-represent non-male athletes.

Association between sports participation history and age of first exposure to high-risk sports with concussion history

The purpose of this study was to examine the association between sports participation history, including estimated age of first exposure (eAFE) to high-risk sports, and concussion history in first year (i.e., freshmen) collegiate athletes. Athletes increased their odds of sustaining a pre-college concussion by 5% [odds ratio(OR) = 1.05 (95%CI:1.05-1.06)] for each additional year of contact sports participation - 24% of all student athletes reported one or more pre-college concussions. When eAFE was analysed dichotomously at age 12, a greater proportion of those who started playing football before age 12 reported a positive concussion history compared to those who started playing football at age 12 or later (Х² = 4.483, p = 0.034, Phi = 0.049). When eAFE was analysed continuously, later eAFE to women's high-risk sports was associated with a lower likelihood of sustaining a pre-college concussion [OR = 0.93 (95%CI:0.88-0.98)]. Our findings suggest that there is a relationship between eAFE to football and to women's high-risk sports and concussion history.

Athlete concussion history recall is underestimated: a validation study of self-reported concussion history among current professional rugby union players

Objective: To assess the concurrent validity and test re-test reliability of the Michigan Traumatic Brain Injury Identification Method (MTBIIM). The psychometric properties of this concussion index were investigated by comparing the agreement between player self-reported diagnosed concussions and medical record diagnosed concussions among professional rugby union players.Study Design: Cross-sectional study i) validation and ii) test re-test reliability.Methods: The MTBIIM was administered via a structured interview to obtain the number and nature of player self-reported concussion histories from players, while contracted to the host club. Self-reported concussion history information was compared to medically recorded data captured between 2008 and 2017. A mixed-effects logistic regression model explored predictors of player self-report accuracy.Results: Data from 62 players (25.39[4.36] years) included 99 unique rugby related concussions. Medically documented concussions (n = 92) per player (1.48 [1.96]) were 30% more than the mean number of self-reported diagnosed (n = 63) concussions per player (1.02 [1.21] events). Overall, self-reported diagnosed concussions and medical record diagnosed concussion histories had a 'fair' level of agreement (k=0.274; SE [0.076]), p=.001). Self-reported lifetime concussion history was signicantly negatively correlated with recall of concussions.Conclusions: Initial concurrent validity of the MTBIIM was found to be fair with the average athlete under-reporting the number of clinically diagnosed concussions.

Age of First Concussion and Cognitive, Psychological, and Physical Outcomes

Objective

This study examined the association between age of first concussion (AFC) and neurocognitive performance, psychological distress, postural stability, and concussion symptoms in healthy collegiate student athletes.

Background

Concussions are common among youth athletes, yet the long-term clinical consequences are largely unknown. We hypothesized that earlier AFC (younger age at first injury) would be associated with worse clinical outcomes.

Design/Methods

Participants included 4,267 collegiate athletes with a positive concussion history from various contact, limited-contact, and non-contact sports (1,818 women and 2,449 men) who completed baseline assessments as part of the Concussion Assessment, Research and Education (CARE) Consortium. Self-reported AFC included both sport- and non-sport-related concussions. Participants completed the Brief Symptom Inventory-18 (assessing psychological distress), the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT, assessing neurocognitive performance and symptoms), the Sport Concussion Assessment Tool symptom evaluation, and the Balance Error Scoring System (assessing postural stability). Generalized linear models were implemented for men and women separately to examine the effects of AFC on clinical outcomes.

Results

Median time from AFC to assessment was four years. After correcting for multiple comparisons, earlier AFC was associated with greater somatic (Exp(B) = 0.96, p = 0.001) and global (Exp(B) = 0.96, p < 0.001) psychological distress on the Brief Symptom Inventory-18, and slower ImPACT reaction time (B = −0.003, p = 0.001) in women. After correcting for multiple comparisons, AFC was not associated with any clinical outcomes in men.

Conclusions

Earlier AFC appears to have some long-term clinical consequences in women but not men, which is consistent with work suggesting that women report greater overall symptoms than men following concussion. These results underscore the importance of minimizing the risk of and properly managing concussions in youth sports, as they may have lasting effects. Future work should examine mechanisms of the AFC sex effects as well as longer-term clinical outcomes in middle and older adulthood.

Concussion Risk Between Individual Football Players: Survival Analysis of Recurrent Events and Non-events

Concussion tolerance and head impact exposure are highly variable among football players. Recent findings highlight that head impact data analyses need to be performed at the subject level. In this paper, we describe a method of characterizing concussion risk between individuals using a new survival analysis technique developed with real-world head impact data in mind. Our approach addresses the limitations and challenges seen in previous risk analyses of football head impact data. Specifically, this demonstrative analysis appropriately models risk for a combination of left-censored recurrent events (concussions) and right-censored recurrent non-events (head impacts without concussion). Furthermore, the analysis accounts for uneven impact sampling between players. In brief, we propose using the Consistent Threshold method to develop subject-specific risk curves and then determine average risk point estimates between subjects at injurious magnitude values. We describe an approach for selecting an optimal cumulative distribution function to model risk between subjects by minimizing injury prediction error. We illustrate that small differences in distribution fit can result in large predictive errors. Given the vast amounts of on-field data researchers are collecting across sports, this approach can be applied to develop population-specific risk curves that can ultimately inform interventions that reduce concussion incidence.

Brain Metabolism Monitoring through CCO Measurements Using All-Fiber-Integrated Super-Continuum Source

For monitoring of concussion, brain function, organ condition and other medical applications, what is needed is a non-invasive method of monitoring tissue metabolism. MRI-based functional imaging technology detects changes in blood oxygenation, a correlate of neural activity, and thus may offer a prediction of prognosis in cases of concussion and other cerebral traumas. Yet, potential relationships between perturbations to cerebral metabolism and patient outcomes cannot be effectively exploited clinically because we lack a practical, low-cost, non-invasive means to monitor cerebral oxygenation and metabolism in the emergency department, operating room, or medical facilities. We have developed a device to optically assay the redox state of Cytochrome-C-Oxidase (CCO), the mitochondrial enzyme responsible for the last step of the electron transport chain. Changes in CCO redox reflect changes in respiratory flux, and thus changes in the rate of oxidative adenosine triphosphate (ATP) synthesis. In other words, changes in CCO reflect brain cell's metabolic activity more directly than the traditional blood oxygenation measurement methods. To non-invasively measure changes in CCO as well as blood oxygenation, we have developed a Super-Continuum Infrared Spectroscopy of Cytochrome-C-Oxidase (SCISCCO) system that uses an all-fiber integrated, super-continuum light source to simultaneously measure both of the new (CCO) and the traditional (blood oxygenation) markers of neural metabolism. The SCISCCO system is validated by confirming the near-infrared spectrum of CCO in vitro. To demonstrate in vivo feasibility, the measured responses of oxygenation and CCO responses to acute ischemia (e.g., blood pressure tests) in human participants are compared to data from the literature. Furthermore, we show that the new device's measurements of oxygenated (HbO) and deoxygenated (HbR) hemoglobin in response to breath hold challenges are principled and consistent with previously reported findings. The validated SCISCCO system is finally applied to measure cerebral oxygenation and the redox state of CCO in participants during an attention test protocol. Twenty-five healthy adults completed an attention task that included nine 60-second periods of attention task, interleaved with 60-s periods of resting baseline. It has been well established that the frontal lobe of the human brain is active during tasks of attention. We therefore predicted that attention task should elicit an increase in HbO concentration accompanied by a decrease in redox state of CCO (e.g., ratio of oxidized CCO to reduced CCO) in frontal lobe brain regions as measured with the SCISCCO system. Our findings are consistent with our predictions: HbO concentration increases while CCO concentration decreases during the attention blocks relative to the resting baseline, thereby indicating an increase in oxidative metabolism of the frontal lobe brain regions of interest. Our systematic, multi-method approach thus validates the new device as well as the validity of the metabolic biomarkers that it measures. The SCISCCO system could be a new tool for monitoring brain and organ metabolism, which could be invaluable for screening concussion patients or use in an operating or emergency room to gauge patient's organ response to treatments.

The Effect of Sport-Related Concussion Injuries on Concussion Symptoms and Health-Related Quality of Life in Male and Female Adolescent Athletes: A Prospective Study

BACKGROUND

Sport-related concussions (SRCs) are associated with short-term disablement, characterized as increased concussion symptoms and lower health-related quality of life (HRQoL). However, there are limited longitudinal data detailing how an SRC affects disablement beyond short-term injury recovery.

PURPOSE

To longitudinally assess the effect of SRCs on symptoms and HRQoL in high school athletes through the 12 months after injury.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The 125 participants included high school athletes who sustained an SRC (female patients, 36%; mean ± SD age, 15.9 ± 1.1 years). The Post-concussion Symptom Scale (PCSS) from the Sport Concussion Assessment Tool-3 and the Pediatric Quality of Life Inventory 4.0 (PedsQL) were completed at enrollment and repeated at 24 to 72 hours (onset) and at 7 days (D7) after the SRC; on the date of return to play (RTP); and at 3, 6, and 12 months (M12) after the SRC. Scores at each time point were compared with the athletes' own baseline via linear mixed models for repeated measures, controlling for age, sex, and history of previous SRC and with patient as a random effect.

RESULTS

Relative to baseline, female patients reported higher PCSS symptom and severity scores at onset (P < .001) and D7 (P < .001), while scores were not higher (P > .05) for RTP through M12. As compared with baseline, male patients reported higher PCSS scores at onset (P < .001) and D7 (P = .003) and severity scores at onset (P < .001) and D7 (P = .016), while the symptom and severity scores were not higher (P > .05) at RTP through M12. Female participants reported lower PedsQL physical scores at onset (P = .006), while scores were not lower (P > .05) from D7 through M12. Female psychosocial scores were not lower (P > .05) at any time after the SRC, while the total PedsQL score was lower at onset (P = .05) but not from D7 through M12. Male physical scores were lower at onset (P < .001) and D7 (P = .001) but not lower (P > .05) from RTP through M12. Male psychosocial and PedsQL scores were unchanged (P > .05) from baseline at onset through M12.

CONCLUSION

After an SRC, high school athletes reported initial disablement (increased symptoms and lower HRQoL) through their RTP. However, after RTP, no similar disablement was detected through 12 months after injury.

Flying may not affect symptom recovery after concussion in Athletes

Objective

To determine if there is a relationship between concussion recovery and airplane travel soon after injury in collegiate athletes and military cadets.

Background

Concussions are a common occurrence in young athletes. Very few studies have examined how flying may influence the clinical progression of a concussive injury.

Design/Methods

This is a prospective cohort study comprised of 3480 college athletes and cadets with concussion obtained from the Concussion Assessment, Research and Education (CARE) Consortium and divided in two groups: those who flew and those who did not fly after concussion. Those with unknown flight status were excluded. Demographics between groups were compared using Chi Square analysis. Symptom burden was calculated by subtracting baseline Sports Concussion Assessment Tool (SCAT3) symptom scores from the post-injury score after flying. Significance between outcome measures and flight status were evaluated using a paired t-test. Analysis of Variance (ANOVA) was used to determine if number of time zones crossed during flight influenced outcomes.

Results

165 athletes flew 31.8 ± 52.3 [SD] hours after injury, 2235 athletes did not fly, and 1080 had unknown flight status. There were no significant study group differences for age, sex, sport, history of prior concussion, and history of headache. No significant group differences were found in days to return to unrestricted play (p = 0.11), days after injury to start graded exertion (p = 0.50), duration of concussion symptoms (p = 0.23), days until return to normal academic performance (p = 0.75), and symptom burden (p = 0.47). Number of time zones crossed did not affect any outcomes.

Conclusions

Airplane travel early after concussion did not significantly affect recovery or severity of concussion symptoms in college athletes and cadets. Further studies need to investigate the possible effects of flying more acutely after injury. These data may help guide future recommendations on flight travel after concussion in athletes.

Recovery Profiles Following Concussion Among Male Athletes with a Family History of Neurodegenerative Disease: Data from the NCAA-DOD CARE Consortium

Objective

Longitudinally assess recovery following concussion in male athletes with fhNDD.

Background

Research suggests that a family history of neurodegenerative disease (fhNDD) may predispose an athlete to abnormal recovery following brain injury. However, no one has longitudinally assessed recovery following concussion in male athletes with fhNDD.

Design/Methods

Data from the NCAA-DOD Grand Alliance: Concussion Assessment, Research, and Education (CARE) Consortium were used to compared male athletes with (n = 51) and without (n = 102) a family history of neurodegenerative disease (Parkinson’s, Alzheimer’s, Non-Alzheimer’s Dementia, and Mild Cognitive Impairment). All athletes completed baseline ImPACT assessments prior to the beginning of their sporting season. Athletes that sustained a concussion were then re-evaluated 24-48 hours post-injury, prior to un-restricted return to play (RTP), and again 6 months post-injury. Athletes without fhNDD were double matched based on age, body mass index, sport category, and concussion history.

Results

Repeated measures ANCOVA models were used to evaluate performance at each post-injury timepoint, while controlling for baseline performance. A group × time interaction was observed for visual memory performance. Post-hoc univariate analyses revealed that male athletes with fhNDD demonstrated significantly poorer visual memory performance 24–48 hours post-injury compared to controls (p ≤ 0.005). Additionally, we found a main effect of group for impulse control, indicating that male athletes with fhNDD demonstrated an increase number of impulse errors at all three post-injury evaluations (p ≤ 0.004). We did not to observe any other group differences (p’s > 0.05).

Conclusions

Our results suggest that male athletes with a family history of neurodegenerative disease may exhibit greater post-injury cognitive deficits compared to controls. Additionally, some deficits may persist for at least 6 months post-injury. Further research is warranted to investigate the interaction between family history of neurodegenerative disease and concussion.

The Influence of Psycho-Stimulant Medication on Concussion Recovery in Athletes with ADHD: Findings from the NCAA-DOD Concussion Consortium

Objective

We sought to longitudinally evaluate concussion recovery in collegiate athletes with ADHD who were and were not taking psycho-stimulant medication.

Background

Psycho-stimulant medication is commonly prescribed to individuals with ADHD. Some have posited that psycho-stimulant medications may mitigate impairments following sport-related concussion. However, no studies longitudinally evaluated the influence of psycho-stimulant medications on concussion recovery in collegiate athletes.

Design/Methods

Data from the NCAA-DOD Grand Alliance: Concussion Assessment, Research, and Education (CARE) Consortium were used to evaluate athletes with ADHD who were not taking psycho-stimulant medications (Rx-ADHD; n = 20), athletes with ADHD who were taking psycho-stimulant medications (Rx+ADHD; n = 20), and controls (n = 80). Athletes with ADHD were double-matched to controls on biological sex, age, and body mass index. All athletes were assessed prior to their sporting season, 24-48 hours post-injury, and again upon unrestricted return-to-play (RTP). Cognition and clinical symptoms were evaluated using the ImPACT test.

Results

Athletes in the Rx-ADHD (10.4 ± 1.5 days) and Rx + ADHD (11.9 ± 1.7) groups exhibited prolonged symptom durations compared to controls (4.2 ± .8; p’s ≤ 0.05). Repeated-measures analyses of covariance (baseline scores = covariate) group × time interactions for multiple variables (p’s ≤ 0.05). Univariate analyses revealed that both groups with ADHD demonstrated poorer verbal memory, and greater total symptoms at 24–48 hours post-injury than controls (p’s ≤ 0.01). Additionally, athletes in the Rx-ADHD group demonstrated poorer cognitive efficiency at 24–48 hours post-injury, and at RTP than controls (p’s ≤ 0.05). Lastly, athletes in the Rx+ADHD group demonstrated slower visual motor speed at 24–48 hours post-injury, and at RTP than controls (p’s ≤ 0.05).

Conclusions

T Our findings suggest that following concussion athletes with ADHD may experience longer recovery than controls, regardless of medicated status. Interestingly, athletes with ADHD who were taking medication did not appear to have different recovery time relative to un-medicated athletes with ADHD.

Neurodevelopmental Disorders and Risk of Concussion: Findings from the NCAA-DOD Concussion Consortium

Objective

We sought to assess the odds and relative risk of concussion in athletes self-reporting a diagnosis of learning disability (LD), attention deficit/hyperactivity disorder (ADHD), and LD + ADHD, relative to controls.

Background

Evidence suggests neurodevelopmental disorders (NDs) may be associated with an increased incidence of concussion, however no study has cross-sectionally and longitudinally assessed the associations of ND subtypes with concussion.

Design/Methods

2014-2017 Data from the NCAA-DOD Grand Alliance: Concussion Assessment, Research, and Education (CARE) Consortium were used to evaluate the likelihood of concussion for athletes with LD (n = 429), ADHD (n = 1513), and LD + ADHD (n = 323), relative to controls (n = 31,130). Odds of concussion history prior to enrollment, and relative risk of incurring a concussion following enrollment were calculated for all groups.

Results

The odds of having a concussion history prior to enrollment for athletes with LD was 1.61 (95% CI 1.31,1.97), and relative risk of incurring a concussion following enrollment for athletes with LD was 1.22 (95% CI .88, 1.69). The odds of having a concussion history for athletes with ADHD was 1.92 (95% CI 1.72, 2.14), and relative risk of incurring a concussion for athletes with ADHD was 1.51 (95% CI 1.29, 1.77). The odds of having a concussion history for athletes with LD + ADHD was 1.85 (95% CI 1.47, 2.33) and relative risk of incurring a concussion for athletes with LD + ADHD was 2.62 (95% CI 2.05, 3.35).

Conclusions

These preliminary results suggest NDs are associated with increased odds and relative risk of incurring a concussion, and athletes with LD + ADHD appear to be most susceptible to concussion. The authors acknowledge that CARE does not capture adequate control for athletic exposures like most sport epidemiology studies. Additionally, these were univariate associations and did not account for sport in which athletes were enrolled. Individuals with NDs could have similar risk once exposure, and sport enrollment are controlled for.

The Influence of Hormonal Contraceptives on Cognitive Recovery in Concussed Collegiate Athletes: Data from the NCAA-DoD CARE Consortium

Objective

To longitudinally examine the relation between hormonal contraceptives and concussion recovery. We hypothesized that female athletes using hormonal contraceptives would exhibit faster recovery times and smaller post-injury alterations in neurological status, cognition, and clinical symptoms than female athletes not using hormonal contraceptives.

Background

Research indicates sex may moderate concussion outcomes, with some females experiencing protracted recovery relative to males. It is hypothesized that fluctuations of sex hormones lead to poorer outcomes in these females. Thus, female athletes taking hormonal contraceptives may exhibit better recovery than their un-medicated counterparts, as their hormone levels are artificially stabilized.

Design/Methods

Data from the NCAA-DOD Grand Alliance: Concussion Assessment, Research, and Education (CARE) Consortium were used to evaluate female athletes who were (n = 50) and were not (n = 50) taking hormonal contraceptives. Baseline assessments were completed prior to athletes’ sport season. Athletes were re-assessed 24–48 hours post-concussion, and again at the unrestricted return-to-play. Length of recovery was defined as days between injury and the unrestricted return-to-play. Neurological status was measured using the Standardized Assessment of Concussion (SAC). Cognitive function and clinical symptoms were measured using the ImPACT test. Participants were matched on age, sex, body mass index, sport, and concussion history.

Results

No group differences in length of recovery were observed (p > 0.05). Across all timepoints, analyses revealed main effects of group for concentration (SAC; p = 0.04), verbal memory (ImPACT; p = 0.03), and cognitive efficiency (ImPACT; p = 0.01). No differences in change scores (relative to baseline) were observed between groups.

Conclusions

The current results suggest that hormonal contraceptives do not influence concussion recovery. However, irrespective of injury status, our findings indicate that females on hormonal contraceptives may exhibit better concentration, working memory, and cognitive efficiency.

Estimated age of first exposure to American football and outcome from concussion

Objective

To examine the association between estimated age of first exposure (eAFE) to American football and clinical measures throughout recovery following concussion.

Background

In collegiate football players, we reported no association between eAFE and baseline neurocognitive function. It is possible that neurocognitive deficits from earlier eAFE to American football, if present, are sufficiently compensated for in otherwise healthy individuals, but when faced with concussion, earlier eAFE may associate with longer symptom recovery, worse cognitive performance, or greater psychological distress.

Design/Methods

Participants were recruited as part of the NCAA–DoD Concussion Assessment, Research and Education (CARE) Consortium. There were 340 NCAA football players (age = 18.9 ± 1.4 years) who were evaluated 24–48 hours following concussion and had valid baseline data and 360 (age = 19.0 ± 1.3 years) who were evaluated at the time they were asymptomatic and had valid baseline data. Participants sustained a medically-diagnosed concussion between baseline testing and post-concussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Brief Symptom Inventory 18 (BSI-18) sub-scores, and Hospital Anxiety and Depression Scale (HADS) scores. The eAFE was defined as the participant’s age at the time of assessment minus the self-reported number of years playing football.

Results

Results of generalized linear modeling suggested that younger eAFE was only associated with lower (better) BSI-18 Somatization (estimate = 0.046, p = 0.046, CI = 0.001–0.091) and BSI-18 Anxiety sub-scores (estimate = 0.053, p = 0.039, CI = 0.003–0.104) at 24–48 hours. The eAFE was not associated with days until asymptomatic, ImPACT composite scores, HADS scores, or other BSI-18 sub-scores.

Conclusions

Earlier eAFE to football was not associated with longer symptom recovery, worse cognitive performance, or greater psychological distress following concussion. Longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion.

Return to play and risk of repeat concussion in collegiate football players: comparative analysis from the NCAA Concussion Study (1999-2001) and CARE Consortium (2014-2017)

OBJECTIVE

We compared data from the National Collegiate Athletic Association (NCAA) Concussion Study (1999-2001) and the NCAA-Department of Defense Concussion Assessment, Research and Education (CARE) Consortium (2014-2017) to examine how clinical management, return to play (RTP) and risk of repeat concussion in collegiate football players have changed over the past 15 years.

METHODS

We analysed data on reported duration of symptoms, symptom-free waiting period (SFWP), RTP and occurrence of within-season repeat concussion in collegiate football players with diagnosed concussion from the NCAA Study (n=184) and CARE (n=701).

RESULTS

CARE athletes had significantly longer symptom duration (CARE median=5.92 days, IQR=3.02-9.98 days; NCAA median=2.00 days, IQR=1.00-4.00 days), SFWP (CARE median=6.00 days, IQR=3.49-9.00 days; NCAA median=0.98 days, IQR=0.00-4.00 days) and RTP (CARE median=12.23 days, IQR=8.04-18.92 days; NCAA median=3.00 days, IQR=1.00-8.00 days) than NCAA Study athletes (all p<0.0001). In CARE, there was only one case of repeat concussion within 10 days of initial injury (3.7% of within-season repeat concussions), whereas 92% of repeat concussions occurred within 10 days in the NCAA Study (p<0.001). The average interval between first and repeat concussion in CARE was 56.41 days, compared with 5.59 days in the NCAA Study (M difference=50.82 days; 95% CI 38.37 to 63.27; p<0.0001).

CONCLUSION

Our findings indicate that concussion in collegiate football is managed more conservatively than 15 years ago. These changes in clinical management appear to have reduced the risk of repetitive concussion during the critical period of cerebral vulnerability after sport-related concussion (SRC). These data support international guidelines recommending additional time for brain recovery before athletes RTP after SRC.

Comparing head impact kinematics simultaneously measured using 6 different sensors in a human cadaver model

Objective

To compare head kinematics measurements obtained from 6 different head impact sensors utilizing different methods of sensor-to-head fixation.

Design

Free-drop impacts (total n = 54) were performed at 3.5 and 5.5 m/s onto to the front, back, side, and top of 2 elderly human cadaveric head-neck specimens: a helmeted (Riddell Revolution Speed) male specimen was dropped onto a NOCSAE testing pad; an un-helmeted female specimen was dropped onto a framed sample of field turf. The specimens were instrumented with an intracranial reference sensor surgically mounted at the approximate head center-of-mass by a rigidly-fixed custom standoff pad, an intra-oral test sensor rigidly fixed to the upper teeth/hard palate by a custom orthodontic appliance, and 4 commercially available head impact sensing systems: X-Patch, Vector mouth guard, HITS (helmeted condition only), and G-Force Tracker (affixed to helmet interior or head band depending on helmet status). Peak linear and rotational head accelerations (PLA and PRA) were compared between each sensor and the intracranial reference sensor using intraclass correlation coefficients (ICC [2, 1]).

Results

Agreement with reference PLA and PRA values differed between sensors, with the greatest agreement observed for the rigidly affixed intraoral sensor (ICC = 0.921, PLA; ICC = 0.810, PRA). Agreement for PLA and PRA, respectively, was: for X-Patch, ICC = 0.638, ICC = 0.155; for Vector mouth guard, ICC = 0.775, ICC = 0.480; for HITS, ICC = 0.662 (PLA only); for G-Force Tracker, ICC = 0.364 (PLA only).

Discussion

Head kinematics measurements during free-drop testing differed among sensors using different approaches of fixation to the head. There was greater agreement with intracranial reference PLA and PRA values for a rigidly affixed intraoral sensor utilizing an orthodontic appliance than for commercially available sensors incorporated into athletic equipment or otherwise non-rigidly affixed to the head. Measurement error attributable to non-rigid sensor-head coupling could potentially be reduced by incorporating an impact sensor into an orthodontic appliance in future research.

Stability of MRI metrics in the advanced research core of the NCAA-DoD concussion assessment, research and education (CARE) consortium

The NCAA-DoD Concussion Assessment, Research, and Education (CARE) consortium is performing a large-scale, comprehensive study of sport related concussions in college student-athletes and military service academy cadets. The CARE "Advanced Research Core" (ARC), is focused on executing a cutting-edge investigative protocol on a subset of the overall CARE athlete population. Here, we present the details of the CARE ARC MRI acquisition and processing protocol along with preliminary analyzes of within-subject, between-site, and between-subject stability across a variety of MRI biomarkers. Two experimental datasets were utilized for this analysis. First, two "human phantom" subjects were imaged multiple times at each of the four CARE ARC imaging sites, which utilize equipment from two imaging vendors. Additionally, a control cohort of healthy athletes participating in non-contact sports were enrolled in the study at each CARE ARC site and imaged at four time points. Multiple morphological image contrasts were acquired in each MRI exam; along with quantitative diffusion, functional, perfusion, and relaxometry imaging metrics. As expected, the imaging markers were found to have varying levels of stability throughout the brain. Importantly, between-subject variance was generally found to be greater than within-subject and between-site variance. These results lend support to the expectation that cross-site and cross-vendor advanced quantitative MRI metrics can be utilized to improve analytic power in assessing sensitive neurological variations; such as those effects hypothesized to occur in sports-related-concussion. This stability analysis provides a crucial foundation for further work utilizing this expansive dataset, which will ultimately be freely available through the Federal Interagency Traumatic Brain Injury Research Informatics System.

Military Blast Injury and Chronic Neurodegeneration: Research Presentations from the 2015 International State-of-the-Science Meeting

Blast-related traumatic brain injury (TBI) is a signature injury of recent military conflicts, leading to increased Department of Defense (DoD) interest in its potential long-term effects, such as chronic traumatic encephalopathy (CTE). The DoD Blast Injury Research Program Coordinating Office convened the 2015 International State-of-the-Science Meeting to discuss the existing evidence regarding a causal relationship between TBI and CTE. Over the course of the meeting, experts across government, academia, and the sports community presented cutting edge research on the unique pathological characteristics of blast-related TBI, blast-related neurodegenerative mechanisms, risk factors for CTE, potential biomarkers for CTE, and treatment strategies for chronic neurodegeneration. The current paper summarizes these presentations. Although many advances have been made to address these topics, more research is needed to establish the existence of links between the long-term effects of single or multiple blast-related TBI and CTE.

Influence of playing rugby on long-term brain health following retirement: a systematic review and narrative synthesis

Objectives

The aim of this review was to systematically investigate long-term brain health in retired rugby players.

Methods

Six databases were systematically searched from inception to January 2018 using Medical Subject Headings and keywords. Two reviewers independently screened studies for inclusion. Cross-sectional studies of living retired male or female rugby players in which at least one cognitive test was used as an outcome measure were included. Data extraction was performed using Strengthening the Reporting of Observational Studies in Epidemiology guidelines. Methodological quality was assessed independently by two reviewers using the Downs and Black methodological quality tool.

Results

This review yielded six studies with an overall methodological quality of 'moderate'. A total of 672 male retired rugby players (mean ages of 38-52 years) were included in this review. Three studies investigated neuropsychological functioning in retired rugby players in comparison with controls, with no significant evidence of decreased performance in the majority of tests when compared with controls. Five out of the six studies explored self-reported measures of cognition. Three studies compared retired rugby players to controls, one of which found significantly increased subjective cognitive complaints among retired rugby players. The other two studies found that persistent postconcussion symptoms were associated with a higher number of self-reported concussions. Two studies reported decreased fine motor control in retired rugby players in comparison with controls. Neurometabolites and electrophysiological changes were explored by two studies, with minimal and non-significant findings.

Conclusions

Overall findings are mixed. Methodological biases reduce the overall study quality and limited the conclusions that can be drawn. Findings of decreased fine motor control in retired athletes may be influenced by lack of controlling for evidence of upper limb musculoskeletal injuries. While some studies show evidence of reduced cognitive function among former athletes, the results are not significantly lower than population norms. Cognitive findings from this review are inconsistent within and across study cohorts and are biased towards positive findings when self-report methods were selected. Current evidence suggests that large gaps remain in the understanding of the cause-and-effect relationships between playing rugby and long-term brain health in retired players.