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Sport-related concussion (SRC) is an important public health issue. White-matter alterations after SRC are widely studied by neuroimaging approaches, such as diffusion magnetic resonance imaging (MRI). Although the exact anatomical location of the alterations may differ, significant white-matter alterations are commonly observed in long fiber tracts, but are never proven. In the present study, we performed streamline tractography to characterize the association between tract length and white-matter microstructural alterations after SRC. Sixty-eight collegiate athletes diagnosed with acute concussion (24-48 h post-injury) and 64 matched contact-sport controls were included in this study. The athletes underwent diffusion tensor imaging (DTI) in 3.0 T MRI scanners across three study sites. DTI metrics were used for tract-based spatial statistics to map white-matter regions-of-interest (ROIs) with significant group differences. Whole-brain white-mater streamline tractography was performed to extract "affected" white-matter streamlines (i.e., streamlines passing through the identified ROIs). In the concussed athletes, streamline counts and DTI metrics of the affected white-matter fiber tracts were summarized and compared with unaffected white-matter tracts across tract length in the same participant. The affected white-matter tracts had a high streamline count at length of 80-100 mm and high length-adjusted affected ratio for streamline length longer than 80 mm. DTI mean diffusivity was higher in the affected streamlines longer than 100 mm with significant associations with the Brief Symptom Inventory score. Our findings suggest that long fibers in the brains of collegiate athletes are more vulnerable to acute SRC with higher mean diffusivity and a higher affected ratio compared with the whole distribution.

Sport-related concussions (SRCs) affect millions of adolescents and young adults annually in the USA; however, current SRC consensus statements provide limited guidance on academic support for students within higher education.To generate consensus on appropriate academic recommendations for clinicians, students, and academic stakeholders to support university students during their recovery.Panelists participated in three stages of a modified Delphi procedure: the first stage included a series of open-ended questions after reviewing a literature review on post-SRC return-to-learn (RTL) in higher education; the second stage asked panelists to anonymously rate the recommendations developed through the first Delphi stage using a 9-point scale; and the final stage offered panelists the opportunity to change their responses and/or provide feedback based on the group's overall ratings.Twenty-two panelists including clinicians, concussion researchers, and academic stakeholders (54.5% female) from 15 institutions and/or healthcare systems participated in a modified Delphi procedure. A total of 42 statements were developed after round one. Following the next two rounds, 27 statements achieved consensus amongst the panel resulting in the four-stage Post-Concussion Collegiate RTL Protocol.There are several unique challenges when assisting university students back to the classroom after SRC. Explicit guidelines on when to seek additional medical care (e.g., if they are experiencing worsening or persistent symptoms) and how to approach their instructor(s) regarding academic support may help the student self-advocate. Findings from the present study address barriers and provide a framework for universities to facilitate a multidisciplinary approach amongst medical and academic stakeholders.

To assess whether the King-Devick (KD) test is useful as a prognostic test for prolonged concussion symptoms by examining the relationship between a) change in performance on KD test from baseline to within two days post-injury and b) the absolute KD time at post-concussion testing, with an outcome of time to return to play (RTP).Prospective Cohort Study.Collegiate varsity athletes in the Concussion Assessment, Research, and Education (CARE) Consortium completed baseline and post-injury King-Devick tests from 2014 to 2018. Two exposures were evaluated: 1) change in KD score from baseline to within two days post-injury and 2) absolute KD score within two days post-injury, adjusted for baseline KD. We used Cox proportional hazards models to analyze the relationships between these exposures and time to RTP post-concussion.A total of 309 concussion injuries were included. Median baseline KD score was 40.0 s (IQR: 35.8, 45.2). Median post-injury KD score was 45.8 s (IQR: 39.8, 57.1). Median number of days until RTP in this cohort was 11 (IQR: 8, 17). Post-injury KD score adjusted for baseline KD had a stronger association with time to RTP duration (HR: 0.99 (0.98, 1.00), p = 0.03) than the difference in KD score from baseline to post-injury (HR: 0.99 (0.99, 1.00), p = 0.07).Higher post-injury KD scores are associated with longer RTP. The association between KD post-concussion test and longer RTP warrants further investigation to assess the utility of the KD for prognostication in a clinical setting.

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 to a control group of non-contact athletes.Generalized estimating equations were used to compare changes in annual, pre-season baseline measures of neurocognitive function, neurobehavioral and psychological symptoms, and postural stability between collegiate soccer players (n = 75; 51 [68%] female soccer players) and non-contact athletes (n = 210; 133 [63%] female non-contact athletes) across three consecutive years.Among all participants, the group-by-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% 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 (PCSS) Symptom Severity (p0.001, Exp(B) = 0.45 [95% CI 0.22-0.95]) scores than non-contact athletes. No other outcome measures were different between soccer players and non-contact athletes.Among collegiate athletes, soccer players report similar or better psychosocial functioning and symptom scores than non-contact athletes. Importantly, neurocognitive functioning, neurobehavioral and psychological symptoms, and postural stability does not worsen over time in collegiate soccer players relative to their non-contact counterparts. Our findings suggest that despite possible exposure to repetitive head impacts (RHIs), collegiate soccer players do not exhibit changes in observable function and symptoms across multiple seasons.

Background: The prevalence of unreported concussions is high, and undiagnosed concussions can lead to worse postconcussion outcomes. It is not clear how those with a history of undiagnosed concussion perform on subsequent standard concussion baseline assessments. Purpose: To determine if previous concussion diagnosis status was associated with outcomes on the standard baseline concussion assessment battery. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Concussion Assessment, Research, and Education (CARE) Consortium participants (N = 29,934) self-reported concussion history with diagnosis status and completed standard baseline concussion assessments, including assessments for symptoms, mental status, balance, and neurocognition. Multiple linear regression models were used to estimate mean differences and 95% CIs among concussion history groups (no concussion history [n = 23,037; 77.0%], all previous concussions diagnosed [n = 5315; 17.8%], ≥1 previous concussions undiagnosed [n = 1582; 5.3%]) at baseline for all outcomes except symptom severity and Brief Symptom Inventory–18 (BSI-18) score, in which negative binomial models were used to calculate incidence rate ratios (IRRs). All models were adjusted for sex, race, ethnicity, sport contact level, and concussion count. Mean differences with 95% CIs excluding 0.00 and at least a small effect size (≥0.20), and those IRRs with 95% CIs excluding 1.00 and at least a small association (IRR, ≥1.10) were considered significant. Results: The ≥1 previous concussions undiagnosed group reported significantly greater symptom severity scores (IRR, ≥1.38) and BSI-18 (IRR, ≥1.31) scores relative to the no concussion history and all previous concussions diagnosed groups. The ≥1 previous concussions undiagnosed group performed significantly worse on 6 neurocognitive assessments while performing better on only 2 compared with the no concussion history and all previous concussions diagnosed groups. There were no between-group differences on mental status or balance assessments. Conclusion: An undiagnosed concussion history was associated with worse clinical indicators at future baseline assessments. Individuals reporting ≥1 previous undiagnosed concussions exhibited worse baseline clinical indicators. This may suggest that concussion-related harm may be exacerbated when injuries are not diagnosed.

To assess whether concussion history adversely affects multisensory integration, we compared susceptibility to the Sound-Induced Flash Illusion (SIFI) in retired professional rugby players compared to controls.Retired professional rugby players ((N = 58) and retired international rowers (N = 26) completed a self-report concussion history questionnaire and the SIFI task. Susceptibility to the SIFI (i.e., perceiving two flashes in response to one flash paired with two beeps) was assessed at three stimulus onset asynchronies (70 ms, 150 ms or 230 ms).Logistic mixed-effects regression modeling was implemented to evaluate how athlete grouping, previous concussion history and total number of years playing sport, impacted the susceptibility to the SIFI task. The statistical significance of a fixed effect of interest was determined by a likelihood ratio test.Former rugby players had significantly more self-reported concussions than the rower group (p 0.001). There was no impact of athlete grouping (i.e., retired professional rugby players and retired international rowers), years participation in elite sport or concussion history on performance in the SIFI.A career in professional rugby, concussion history or number of years participating in professional rugby was not found to be predictive of performance on the SIFI task.

Concussions are common among youth athletes and could disrupt critical neurodevelopment. This study examined the association between age of first concussion (AFC) and neurocognitive performance, psychological distress, postural stability, and symptoms commonly associated with concussion in healthy collegiate men and women student athletes.Participants included 4267 collegiate athletes from various contact, limited-contact, and non-contact sports (1818 women and 2449 men) who completed baseline assessments as part of the Concussion Assessment, Research and Education (CARE) Consortium. Psychological distress was assessed with the Brief Symptom Inventory 18; neurocognitive performance was assessed with the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT); symptoms commonly associated with concussion were assessed with the ImPACT Post-Concussion Symptom Scale; postural stability was assessed with the Balance Error Scoring System. Generalized linear models were used to examine the effects of AFC on clinical outcomes separately in men and women.Later AFC was associated with lower global (Exp(B) = 0.96, P = 0.001) and somatic (Exp(B) = 0.96, P = 0.002) psychological distress on the Brief Symptom Inventory 18 and faster ImPACT reaction time (B = - 0.003, P = 0.001) in women. AFC was not associated with any clinical outcomes in men.Younger AFC was associated with some differences in psychological distress and reaction time among women but not men; however, these results are likely not clinically meaningful. Sociodemographic disparities, pre-existing conditions, and sport type may impact clinical and cognitive outcomes in collegiate athletes more than concussion history. Future work should examine the relationship between AFC and lifespan-related outcomes.

Evidence suggests neurodevelopmental disorders (NDs) may be associated with an increased incidence of concussion, but no studies have cross-sectionally and longitudinally assessed the associations of NDs and sex with concussion in collegiate athletes. We sought to assess the odds and relative risk (RR) of concussion in athletes self-reporting a diagnosis of attention deficit/hyperactivity disorder (ADHD), learning disability (LD), and ADHD+LD. Data from the Concussion Assessment, Research and Education (CARE) Consortium (2014–2017) were used to evaluate the likelihood of concussion for male and female athletes with ADHD, LD, and ADHD+LD, relative to controls. Odds ratios (ORs) of concussion history prior to enrollment and relative risk ratios for incurring a concussion following enrollment, with and without concussion history were calculated for all groups. Athletes with self-reported diagnosis of ADHD, LD, and ADHD+LD were more likely to report a single concussion (OR range = 1.528 to 1.828) and multiple concussions (OR range = 1.849 to 2.365) prior to enrollment in the CARE Consortium, irrespective of sex compared with control athletes. While enrolled in CARE, male athletes with ADHD, LD, and ADHD+LD had greater risk of incurring a concussion (RR range = 1.369 to 2.243) than controls, irrespective of concussion history. Male athletes with ADHD+LD with concussion history (RR = 2.221) and without concussion history (RR = 1.835) had greater risk of incurring a concussion than controls. These results suggest NDs may be associated with increased odds of single and multiple concussions, irrespective of sex. However, when we accounted for concussion history, it appears only male athletes with ADHD+LD had greater risk than respective controls. There were no significant differences between females and males with ADHD, LD, or ADHD+LD for either odds of concussion history or risk for incurring concussion.

Background: The Vestibular/Ocular-Motor Screening (VOMS) is a valuable component of acute (Purpose: To analyze VOMS, SCAT3, and ImPACT to evaluate the test-retest reliability of consecutive-year preseason baseline assessments to directly compare the diagnostic utility of these tools when incorporating baseline assessments versus using postinjury data alone to identify acute SRC. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Preseason and postinjury VOMS, SCAT3, ImPACT Post-Concussion Symptom Scale (PCSS), and ImPACT composite scores were analyzed for 3958 preseason (47.7% female) and 496 acute (≤48 hours) SRC (37.5% female) collegiate athlete evaluations in the National Collegiate Athletic Association—Department of Defense Concussion Assessment Research and Education Consortium. Descriptive statistics, Kolmogorov-Smirnov significance, and Cohen d effect size were calculated. Consecutive-year baseline reliability was evaluated for a subset of 447 athlete encounters using Pearson r, Cohen κ, Cohen d, and 2-way mixed intraclass correlation coefficients (ICCs). Wilcoxon signed rank tests were used to determine the statistical significance between population performances, and the 90% reliable change index (RCI) was calculated from the test-retest results. Preseason to postinjury change scores were then calculated from each tool’s RCI. Finally, receiver operating characteristic (ROC) curve analyses were conducted, and DeLong method was used to compare the area under the curve (AUC) of raw postinjury scores versus change scores from preseason baseline assessments. Potential effects of sex, medical history (learning disorders or attention-deficit/hyperactivity disorder), and outlier data were also explored. Results: Effect sizes were large, and overall predictive utilities were clinically useful for postinjury VOMS Total ( d = 2.44; AUC = 0.85), the SCAT3 Symptom Evaluation total severity score ( d = 1.74; AUC = 0.82), and the ImPACT PCSS total severity score ( d = 1.67; AUC = 0.80). Comparatively, effect sizes were small and predictive utilities were poor for Standardized Assessment of Concussion (SAC), modified Balance Error Scoring System (mBESS), and all ImPACT composites ( d = 0.11-0.46; AUC = 0.48-0.59). Preseason baseline test-retest reliability was poor to moderate ( r = 0.23-0.52; κ = 0.32-0.36; ICC = 0.36-0.68) for all assessments except ImPACT Visual Motion Sensitivity ( r = 0.73; ICC = 0.85). Incorporating baseline scores for VOMS Total, SCAT3 (Symptom Evaluation, SAC, mBESS), ImPACT PCSS, or ImPACT composites did not significantly improve AUCs. Conclusion: VOMS Total and symptom severity (SCAT3, PCSS) total scores had large effect sizes and clinically useful AUCs for identifying acute concussion. However, all tools demonstrated high within-patient test-retest variability, resulting in poor reliability. The findings in this sample of collegiate athletes suggest that incorporating baseline assessments does not significantly increase diagnostic yield for acute concussion.

Few studies have analyzed the Sport Concussion Assessment Tool's (SCAT) utility among athletes whose concussion assessment is challenging. Using a previously published algorithm, we identified possible and probable concussions at

Context Nearly 44 million youth participate in organized youth sports programs in the United States each year. However, approximately 25% of parents have considered removing their children from sports due to the fear of concussion. Objective To determine which adult decision-making modifiers (eg, gender, educational attainment, career type) influenced support for youth contact-sports participation. Design Cross-sectional study. Setting Midwestern university and medical center. Patients or Other Participants Convenience sample of staff and faculty (N = 5761; 73.9% female) from 2017 to 2018. Main Outcome Measure(s) Support for youth contact-sports participation using multivariate binary logistic regression to calculate odds ratios and 95% CIs. Results The sample was split between adults with children (AWCs; n = 3465, age = 45.39 ± 13.27 years, 76.72% female) and adults without children (AWOCs; n = 2296, age = 30.84 ± 9.01 years, 70.26% female). Among AWCs, those who obtained a bachelor's degree or higher were more likely to support contact-sports participation. Females were more inclined to allow all contact sports, specifically football (odds ratio [OR] = 2.22; 95% CI = 1.64, 3.01) and ice hockey (OR = 1.98; 95% CI = 1.42, 2.78). Overall, previous adult sport participation, increasing number of children, and child gender were significant modifying variables in greater support of youth contact-sports participation among AWCs (P < .001). Among AWOCs, previous sport participation in football (OR = 3.27; 95% CI = 2.14, 4.87), ice hockey (OR = 4.26; 95% CI = 2.23, 8.17), or soccer (OR = 2.29; 95% CI = 1.48, 3.54) increased the likelihood of an adult supporting contact-sports participation. Lastly, all adults were less inclined to support a daughter participating in any contact sport than a son. Conclusions These results reveal adult- and child-specific variables that may influence youth contact-sports participation. These decisions may be developed through the lens of certain gender role beliefs and may lead adults to perceive certain sports as more appropriate for sons than daughters.

To derive minimum detectable change (MDC) across individual Vestibular-Ocular Motor Screening (VOMS) items and VOMS overall score in 17-25 years old collegiate athletes and to examine false positive rates.Participants (n = 378) completed VOMS pre-season for two consecutive years. MDC was identified for individual VOMS symptom items and NPC distance (cm). Both total and change methods of VOMS scoring were included in analysis.Regarding total scoring, MDC for ocular VOMS symptom items was 1 and MDC for vestibular VOMS symptoms items was 2. MDC for NPC was 4 cm and for VOMS overall score was 10. Regarding change scoring, MDC for each VOMS symptom item was 1, and for VOMS overall score was 8. False positives ranged from 5.3% to 15.9%.This study presents MDCs for each VOMS item and overall VOMS score, using total and change scoring. These values can be considered true change outside measurement error with 95% confidence in a 17-25 year old collegiate athlete population.

Context There is growing interest in the relation between repetitive concussions and mental health; however, studies on the relation between concussion frequency and adverse mental health outcomes among female and male youth are lacking. Objective To examine the association between self-reported concussion frequency and non-fatal suicidal behaviors among youth and to explore the potential interaction of biological sex. Design Retrospective cross-sectional survey. Setting National Youth Risk Behavior Surveillance System. Participants 28,442 United States secondary school students. Main Outcome Measure(s) Exposure variables included frequency of self-reported sport/recreation-related concussion within the previous 12-months (0, 1, ≥2). Outcome variables included feelings of self-reported sadness/hopelessness, suicidal ideation, planning, and attempts. Covariates included age, sex, race/ethnicity, bullying victimization, sexual orientation, and physical activity. Results Students that reported ≥2 concussions were at significantly greater odds of reporting suicidal attempts (AOR = 2.03 [95% CI = 1.43, 2.88]) when compared to students reporting a single concussive event during the past 12-months. However, sex interactions revealed that this finding may be driven by males; the strength of associations did not increase from single to multiple concussions among females. Conclusions Findings from the present study suggest that adolescents who self-reported concussion were at increased odds of reporting poor mental health and suicidal behaviors. Moreover, increased number of concussive events may be associated with significantly greater odds of reporting suicidal attempts, particularly among males. Irrespective of sex, health care professionals should closely monitor mental health behaviors in adolescents with repetitive concussions, especially those that occur in close temporal proximity.

Computer-based neurocognitive tests are widely used in sport-related concussion management, but the performance of these tests is not well understood in the participant population with attention-deficit/hyperactivity disorder (ADHD) and/or learning disorder (LD). This research estimates the sensitivity and specificity performance of the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) computer-based neurocognitive test in identifying concussion in this population.Study participants consisted of collegiate university athletes and military service academy cadets from the National Collegiate Athletic Association-Department of Defense CARE Consortium who completed the ImPACT test between 2014 and 2021. Participants who self-identified as belonging to one of the subgroups of interest (ADHD with or without LD [ADHD:LD+/-], LD with or without ADHD [LD:ADHD+/-], ADHD and/or LD [ADHD a/o LD]) and completed a baseline (1874 ADHD:LD+/-, 779 LD:ADHD+/-, 2338 ADHD a/o LD) or 24-48 h post-concussion (175 ADHD:LD+/-, 77 LD:ADHD+/-, 216 ADHD a/o LD) ImPACT assessment were included. Sensitivity and specificity were calculated using a normative data method and three machine learning classification methods: logistic regression, classification and regression tree, and random forest.Using the four methods, participants with ADHD:LD+/- had sensitivities that ranged from 0.474 to 0.697, and specificities that ranged from 0.538 to 0.686. Participants with LD:ADHD+/- had sensitivities that ranged from 0.455 to 0.688, and specificities that ranged from 0.456 to 0.588. For participants with ADHD a/o LD, sensitivities ranged from 0.542 to 0.755, and specificities ranged from 0.451 to 0.724.For all subgroups and analytical methods, the results illustrate sensitivity and specificity values below typically accepted levels indicative of clinical utility. These findings support that using ImPACT alone may be insufficient to inform concussion diagnoses and encourages the use of a multi-dimensional concussion assessment.

Sport-related concussion is recognized as a significant injury with variable recovery rates. This study defined the acute natural history of sport concussion in male and female collegiate athletes participating in a broad array of sports. We conducted a prospective, longitudinal investigation among collegiate student athletes (n = 34,709) from 30 academic institutions. Primary outcomes included the time (days) from injury until initiation of a return to participation (RTP) protocol and time from injury until medical clearance for unrestricted RTP. Concussed athletes (n = 1751, 19.2 years, 63.2% male) participating in 22 different sports began the RTP protocol in a median 6.4 (IQR 3.7–11.8) days. Time to initiate the RTP protocol was lengthened by less frequent post-injury assessments, greater initial post-injury symptom severity, limited contact sports participation, practice/training injuries, and three or more prior concussions. The median total RTP duration was 12.8 (IQR 8.7–20.1) days. Total RTP duration was shorter with ADHD medication usage, males, and greater assessment frequency; while greater initial post-injury symptom severity, practice-/training-related injuries, and three or more prior concussions had longer recoveries. Although median recovery times are consistent with previous guidelines, it was not until 1 month post-injury that a preponderance of collegiate athletes were cleared to begin the RTP protocol (92%) or cleared for unrestricted sport participation (85%). Intrinsic and extrinsic factors had a small effect, altering recovery trajectories by up to 2 days, suggesting a largely unified approach to post-injury monitoring and management across all athletes. These data represent a shift from previous classification parameters of normal clinical recovery.

The purpose of this study was to describe the mechanism of injury (MOI) and examine factors associated with greater risk for specific MOIs involving concussions in collegiate soccer players.Participants included 3,288 collegiate soccer players from 28 institutions across four competitive seasons, 2014-17. MOIs were documented for 262 soccer-related concussions during the study and placed into one of four categories: collisions, unintentional contact, aerial challenges, and others.70% of the concussions occurred in DI soccer players. Collisions and unintentional contact were the MOIs that resulted in 66.5% of all concussions. DI and DIII soccer players sustained more concussions by unintentional contact versus collisions and aerial challenges when compared to their DII counterparts. Defenders were more likely than midfielders to sustain concussions by aerial challenges than collisions. As expected, the field players experienced more concussions as a result of collisions, unintentional contact, and aerial challenges when compared to goalkeepers.Future research should explore preventive strategies for decreasing collisions, especially during aerial challenges while heading the soccer ball, and unintentional contacts from errant balls in soccer in order to decrease concussion risk.

Increasing attention is directed on identifying aspects of football participation for targeted policy change that reduces concussion risk. Prior work evaluated concussion risk during the pre- and regular-seasons, leaving the spring season largely unexplored. This nationally representative observational investigation of 19 Division I collegiate football programs evaluated concussion rates and head impact exposure during the pre-season, regular season, and spring practices from 2014-2019. All participating programs recorded incidence concussions and a subset (n=6) also measured head impact exposure. Analyses by time of year and session type indicated concussion rates and head impact exposure during all practice sessions and contact only practices were significantly higher in the spring and pre-season compared to the regular season (p's0.05). Concussion rates during the spring season and pre-season were statistically similar. This investigation identified comparable concussion risk between the spring and pre-seasons, highlighting the need for targeted policy intervention to protect athlete health and safety.

The use of head kinematic measurement devices has recently proliferated owing to technology advances that make such measurement more feasible. In parallel, demand to understand the biomechanics of head impacts and injury in sports and the military has increased as the burden of such loading on the brain has received focused attention. As a result, the field has matured to the point of needing methodological guidelines to improve the rigor and consistency of research and reduce the risk of scientific bias. To this end, a diverse group of scientists undertook a comprehensive effort to define current best practices in head kinematic measurement, culminating in a series of manuscripts outlining consensus methodologies and companion summary statements. Summary statements were discussed, revised, and voted upon at the Consensus Head Acceleration Measurement Practices (CHAMP) Conference in March 2022. This manuscript summarizes the motivation and methods of the consensus process and introduces recommended reporting checklists to be used to increase transparency and rigor of future experimental design and publication of work in this field. The checklists provide an accessible means for researchers to apply the best practices summarized in the companion manuscripts when reporting studies utilizing head kinematic measurement in sport and military settings.

Concussion is a growing public health concern and generating concussion prevention programs depends on identifying high-risk sports and characteristics. Identifying the roles of sport, sex, and participation level (e.g., high school versus collegiate athletics) in concussion risk would facilitate more informed decision-making regarding sports participation and generate better targeted prevention strategies. The current study’s objectives were to: (1) determine the magnitude and hierarchy of sports-related concussion (SRC) risk across an array of events and (2) evaluate the modifying roles of sex, participation level, and session type on SRC rates. A literature search was conducted on PubMed, searching concussion studies published between 2001 and December 2019. Inclusion criteria for studies required: (1) concussion occurred during sport, (2) that the SRC was clinically diagnosed, and (3) athlete exposures and concussions could be extracted or estimated. A study was excluded if it: (1) was not an original research article, (2) was not written in English language, (3) was an animal study, (4) did not have enough data to calculate SRC rates, (5) included professional or youth sample, and/or (6) contained data collected prior to 2001. The meta-analysis and meta-regression analyses were fit using a random effects model. Search results returned 2695 unique research articles, with 83 studies included in analyses. Sport, sex, participation level, and session type all significantly influenced SRC rates. Overall, rugby had the highest concussion rate and was classified as the highest risk sport (28.25 concussions per 10,000 athlete exposures). Overall, females had a higher concussion rate than males. Only lacrosse demonstrated a higher concussion rate for males compared to females. Collegiate athletes had higher concussion rates than high school athletes. Games were associated with 2.01 more concussions per 10,000 AEs than practices. This meta-analysis demonstrated rugby has the highest concussion risk, followed by American Football, ice hockey, and wrestling. Concussion risk was influenced by sport, sex, participation, and session. Identifying the factors and environments that influence concussion risk can facilitate risk reduction and prevention strategies.

Highlights • Previous concussion was associated with 2 times increased odds of incident concussion, while wearing a mouthguard was protective against incident concussion, reducing odds by 57%. • Overall, concussion mechanisms did not significantly differ between sexes. • Females took significantly longer to reach asymptomatic and return-to-play clearance. Within the first 2 weeks post-concussion, 86.11% of males reached asymptomatic, while only 45.50% of females reached the same phase of recovery. • Most males (91.67%) were cleared for return-to-play within 3 weeks of their concussion, compared to less than one-half (45.50%) of females., Objective Since concussion is the most common injury in ice hockey, the objective of the current study was to elucidate risk factors, specific mechanisms, and clinical presentations of concussion in men's and women's ice hockey. Methods Ice hockey players from 5 institutions participating in the Concussion Assessment, Research, and Education Consortium were eligible for the current study. Participants who sustained a concussion outside of this sport were excluded. There were 332 (250 males, 82 females) athletes who participated in ice hockey, and 47 (36 males, 11 females) who sustained a concussion. Results Previous concussion (odds ratio (OR) = 2.00; 95% confidence interval (95% CI): 1.02‒3.91) was associated with increased incident concussion odds, while wearing a mouthguard was protective against incident concussion (OR = 0.43; 95%CI: 0.22‒0.85). Overall, concussion mechanisms did not significantly differ between sexes. There were specific differences in how concussions presented clinically across male and female ice hockey players, however. Females (9.09%) were less likely than males (41.67%) to have a delayed symptom onset (p = 0.045). Additionally, females took significantly longer to reach asymptomatic (p = 0.015) and return-to-play clearance (p = 0.005). Within the first 2 weeks post-concussion, 86.11% of males reached asymptomatic, while only 45.50% of females reached the same phase of recovery. Most males (91.67%) were cleared for return to play within 3 weeks of their concussion, compared to less than half (45.50%) of females. Conclusion The current study proposes possible risk factors, mechanisms, and clinical profiles to be validated in future concussions studies with larger female sample sizes. Understanding specific risk factors, concussion mechanisms, and clinical profiles of concussion in collegiate ice hockey may generate ideas for future concussion prevention or intervention studies., Graphical Abstract Image, graphical abstract

Preliminary evidence indicates that genetic factors associated with having a family history of neurodegenerative disease (fhNDD) may predispose an individual to persistent symptoms and poorer cognitive performance after concussion. No previous study, however, longitudinally examined athletes with (+) and without (-) a fhNDD. Therefore, we aimed to compare clinical symptoms and cognitive performance of fhNDD+ and fhNDD- athletes at baseline and at multiple time points after concussion. Questionnaire data from the Concussion Assessment, Research and Education (CARE) Consortium were used to identify male athletes and cadets with (

Symptom resolution is a key marker in determining fitness for return to activity following concussion, but in some cases, distinguishing persistent symptoms due to concussion versus symptoms related to other factors can be challenging. To determine base rates of postconcussional syndrome (PCS) diagnostic categorization in healthy cadets and student athletes with no recent concussion. 13,009 cadets and 21,006 student athletes completed baseline preseason testing. After inclusion/exclusion criteria were applied, the final sample included 12,039 cadets [9123 men (75.8%); 2916 women (24.2%)] and 18,548 student athletes [10,192 men (54.9%); 8356 women (45.1%)]. Participants completed the Sport Concussion Assessment Tool–3rd Edition (SCAT3) symptom evaluation as part of baseline preseason testing. The PCS diagnostic categorization was classified by the International Classification of Diseases, 10th Revision (ICD-10) symptom criteria for PCS. In the absence of recent concussion, subgroups of cadets (17.8% of men; 27.6% of women) and student athletes (11.4% of men; 20.0% of women) reported a cluster of symptoms that would meet the ICD-10 symptom criteria for PCS. Participants with insufficient sleep and/or preexisting conditions (e.g., mental health problems), freshmen cadets, and cadets at the U.S. Coast Guard Academy and at the U.S. Air Force Academy (freshmen were tested during basic cadet training) were more likely to report a cluster of symptoms that would meet the ICD-10 symptom criteria for PCS. The ICD-10 symptom criteria for PCS can be mimicked by preexisting conditions, insufficient sleep, and/or stress. Findings support person-specific assessment and management of symptoms following concussion.

Objective: As part of an initiative led by the Brain Injury Special Interest Group Mild Traumatic Brain Injury (TBI) Task Force of the American Congress of Rehabilitation Medicine (ACRM) to update the 1993 ACRM definition of mild TBI, the present study aimed to characterize current expert opinion on diagnostic considerations. Design: Cross-sectional web-based survey. Setting: Not applicable. Participants: An international, interdisciplinary group of clinician-scientists (N=31) with expertise in mild TBI completed the survey by invitation between May and July 2019 (100% completion rate). Interventions: Not applicable. Main Outcome Measures: Ratings of agreement with statements related to the diagnosis of mild TBI and ratings of the importance of various clinical signs, symptoms, test findings, and contextual factors for increasing the likelihood that the individual sustained a mild TBI, on a scale ranging from 1 (“not at all important”) to 10 (“extremely important”). Results: Men (n=25; 81%) and Americans (n=21; 68%) were over-represented in the sample. The survey revealed areas of expert agreement (eg, acute symptoms are diagnostically useful) and disagreement (eg, whether mild TBI with abnormal structural neuroimaging should be considered the same diagnostic entity as “concussion”). Observable signs were generally rated as more diagnostically important than subjective symptoms (Wilcoxon signed ranks test, Z=3.77; P

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...

To develop a predictive model for sport-related concussion in collegiate athletes and military service academy cadets using baseline data collecting during the pre-participation examination. Baseline assessments were performed in 15,682 participants from 21 US academic institutions and military service academies participating in the CARE Consortium Study during the 2015–2016 academic year. Participants were monitored for sport-related concussion during the subsequent season. 176 baseline covariates mapped to 957 binary features were used as input into a support vector machine model with the goal of learning to stratify participants according to their risk for sport-related concussion. Performance was evaluated in terms of area under the receiver operating characteristic curve (AUROC) on a held-out test set. Model inputs significantly associated with either increased or decreased risk were identified. 595 participants (3.79%) sustained a concussion during the study period. The predictive model achieved an AUROC of 0.73 (95% confidence interval 0.70–0.76), with variable performance across sports. Features with significant positive and negative associations with subsequent sport-related concussion were identified. This predictive model using only baseline data identified athletes and cadets who would go on to sustain sport-related concussion with comparable accuracy to many existing concussion assessment tools for identifying concussion. Furthermore, this study provides insight into potential concussion risk and protective factors.

To optimally care for concussed individuals, a multi-dimensional approach is critical and a key component of this assessment in the athletic environment is computer-based neurocognitive testing. However, there continues to be concerns about the reliability and validity of these testing tools. The purpose of this study was to determine the sensitivity and specificity of three common computer-based neurocognitive tests (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT], CNS Vital Signs, and CogState Computerized Assessment Tool [CCAT]), to provide guidance on their clinical utility. This study analyzed assessments from a cohort of collegiate athletes and non-varsity cadets from the NCAA-DoD CARE Consortium. The data were collected from 2014–2018. Study participants were divided into two testing groups [concussed, n = 1414 (baseline/24–48 h) and healthy, n = 8305 (baseline/baseline)]. For each test type, change scores were calculated for the components of interest. Then, the Normative Change method, which used normative data published in a similar cohort, and the Reliable Change Index (RCI) method were used to determine if the change scores were significant. Using the Normative Change method, ImPACT performed best with an 87.5%-confidence interval and 1 number of components failed (NCF; sensitivity = 0.583, specificity = 0.625, F1 = 0.308). CNS Vital Signs performed best with a 90%-confidence interval and 1 NCF (sensitivity = 0.587, specificity = 0.532, F1 = 0.314). CCAT performed best when using a 75%-confidence interval and 2 NCF (sensitivity = 0.513, specificity = 0.715, F1 = 0.290). When using the RCI method, ImPACT performed best with an 87.5%-confidence interval and 1 NCF (sensitivity = 0.626, specificity = 0.559, F1 = 0.297). When considering all three computer-based neurocognitive tests, the overall low sensitivity and specificity results provide additional evidence for the use of a multi-dimensional assessment for concussion diagnosis, including symptom evaluation, postural control assessment, neuropsychological status, and other functional assessments.

OBJECTIVEPrevious studies have shown that clinically asymptomatic high-acceleration head impacts (HHIs) may be associated with neuronal and axonal injury, as measured by advanced imaging and biomarkers. Unfortunately, these methods of measurement are time-consuming, invasive, and costly. A quick noninvasive measurement tool is needed to aid studies of head injury and its biological impact. Quantitative pupillometry is a potential objective, rapid, noninvasive measurement tool that may be used to assess the neurological effects of HHIs. In this study, the authors investigated the effect of HHIs on pupillary metrics, as measured using a pupillometer, in the absence of a diagnosed concussion.METHODSA prospective observational cohort study involving 18 high school football athletes was performed. These athletes were monitored for both the frequency and magnitude of head impacts that they sustained throughout a playing season by using the Head Impact Telemetry System. An HHI was defined as an impact exceeding 95g linear acceleration and 3760 rad/sec2 rotational acceleration. Pupillary assessments were performed at baseline, midseason, after occurrence of an HHI, and at the end of the season by using the NeurOptics NPi-200 pupillometer. The Sport Concussion Assessment Tool, 5th Edition (SCAT5), was also used at each time point. Comparisons of data obtained at the various time points were calculated using a repeated-measures analysis of variance and a t-test.RESULTSSeven athletes sustained HHIs without a related diagnosed concussion. Following these HHIs, the athletes demonstrated decreases in pupil dilation velocity (mean difference 0.139 mm/sec; p = 0.048), percent change in pupil diameter (mean difference 3.643%; p = 0.002), and maximum constriction velocity (mean difference 0.744 mm/sec; p = 0.010), compared to measurements obtained at the athletes’ own midseason evaluations. No significant changes occurred between the SCAT5 subtest scores calculated at midseason and those after a high impact, although the effect sizes (Cohen’s d) on individual components ranged from 0.41 to 0.65.CONCLUSIONSMeasurable changes in pupil response were demonstrated following an HHI. These results suggest that clinically asymptomatic HHIs may affect brain reflex pathways, reflecting a biological injury previously seen when more invasive methods were applied.

Introduction Increased risk of musculoskeletal (MSK) injury post-concussion has been reported in collegiate athletes, yet it is unknown if professional football athletes are at the same risk of secondary injury. The objective of this study was to determine if the risk of MSK injury in National Football League (NFL) athletes increases after concussion. Methods NFL injury reports from 2013 to 2017 were collected from public websites. Concussed athletes (n=91) were equally matched to a non-injured control and an athlete with an incident of musculoskeletal (MSK) injury. Results Following their return to sport, concussed athletes were 2.35 times more likely to have a subsequent MSK injury relative to non-injured controls (95% CI: 2.35 [1.25, 4.44], P = 0.01), but were no more likely than athletes with an incident MSK injury (P = 0.55). Likewise, athletes with an incident MSK injury were no more likely to have a subsequent MSK injury than controls (P = 0.08). Discussion Increased odds of MSK injury in the 12-week period following a concussion in professional football athletes warrants future research on the acute effects of concussion and the relationship to MSK injury risk.

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.

ObjectiveTo examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion.MethodsParticipants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)–Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24–48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football.ResultsIn unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed (R2 = 0.031, p = 0.012) at 24–48 hours following injury and lower (better) BSI-18 Somatization subscores (R2 = 0.014, p = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores.ConclusionEarlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion.

ObjectiveTo study longitudinal recovery trajectories of white matter after sports-related concussion (SRC) by performing diffusion tensor imaging (DTI) on collegiate athletes who sustained SRC.MethodsCollegiate athletes (n = 219, 82 concussed athletes, 68 contact-sport controls, and 69 non–contact-sport controls) were included from the Concussion Assessment, Research and Education Consortium. The participants completed clinical assessments and DTI at 4 time points: 24 to 48 hours after injury, asymptomatic state, 7 days after return-to-play, and 6 months after injury. Tract-based spatial statistics was used to investigate group differences in DTI metrics and to identify white-matter areas with persistent abnormalities. Generalized linear mixed models were used to study longitudinal changes and associations between outcome measures and DTI metrics. Cox proportional hazards model was used to study effects of white-matter abnormalities on recovery time.ResultsIn the white matter of concussed athletes, DTI-derived mean diffusivity was significantly higher than in the controls at 24 to 48 hours after injury and beyond the point when the concussed athletes became asymptomatic. While the extent of affected white matter decreased over time, part of the corpus callosum had persistent group differences across all the time points. Furthermore, greater elevation of mean diffusivity at acute concussion was associated with worse clinical outcome measures (i.e., Brief Symptom Inventory scores and symptom severity scores) and prolonged recovery time. No significant differences in DTI metrics were observed between the contact-sport and non–contact-sport controls.ConclusionsChanges in white matter were evident after SRC at 6 months after injury but were not observed in contact-sport exposure. Furthermore, the persistent white-matter abnormalities were associated with clinical outcomes and delayed recovery time.

Context Assessments of the duration of concussion recovery have primarily been limited to sport-related concussions and male contact sports. Furthermore, whereas durations of symptoms and return-to-activity (RTA) protocols encompass total recovery, the trajectory of each duration has not been examined separately. Objective To identify individual (eg, demographics, medical history), initial concussion injury (eg, symptoms), and external (eg, site) factors associated with symptom duration and RTA-protocol duration after concussion. Design Cohort study. Setting Three US military service academies. Patients or Other Participants A total of 10 604 cadets at participating US military service academies enrolled in the study and completed a baseline evaluation and up to 5 postinjury evaluations. A total of 726 cadets (451 men, 275 women) sustained concussions during the study period. Main Outcome Measure(s) Number of days from injury (1) until the participant became asymptomatic and (2) to complete the RTA protocol. Results Varsity athlete cadets took less time than nonvarsity cadets to become asymptomatic (hazard ratio [HR] = 1.75, 95% confidence interval = 1.38, 2.23). Cadets who reported less symptom severity on the Sport Concussion Assessment Tool, third edition (SCAT3), within 48 hours of concussion had 1.45 to 3.77 times shorter symptom-recovery durations than those with more symptom severity. Similar to symptom duration, varsity status was associated with a shorter RTA-protocol duration (HR = 1.74, 95% confidence interval = 1.34, 2.25), and less symptom severity on the SCAT3 was associated with a shorter RTA-protocol duration (HR range = 1.31 to 1.47). The academy that the cadet attended was associated with the RTA-protocol duration (P < .05). Conclusions The initial total number of symptoms reported and varsity athlete status were strongly associated with symptom and RTA-protocol durations. These findings suggested that external (varsity status and academy) and injury (symptom burden) factors influenced the time until RTA.