A National Study on the Effects of Concussion in Collegiate Athletes and US Military Service Academy Members: The NCAA-DoD Concussion Assessment, Research and Education (CARE) Consortium Structure and Methods

Progesterone and Estradiol Levels Associated with Concussion and Clinical Outcomes and Recovery in Female Athletes and Cadets

INTRODUCTION

Female athletes are underrepresented in concussion research, and few studies have investigated associations of ovarian hormones with concussion outcomes. This study explored associations of concussion with levels and variability of progesterone, estradiol, and their ratio (P/E) and examined relationships of hormone levels with clinical measures and recovery after concussion in CARE Consortium female athletes and cadets.

METHODS

Female participants enrolled ( n = 749) at pre-injury baseline. Participants with concussion (mean age, 19.34 yr; n = 130, 90 athletes, 40 nonathlete cadets) completed one or more visits at nonstandardized times of day: immediately post-injury, 24 h post-injury, upon initiating the return-to-play protocol (Init RTP), and 7 d following unrestricted return-to-play (PRTP). Controls (mean age, 19.85 yr; n = 67, 61 athletes, 6 nonathlete cadets) completed similar visits. Linear mixed models and general linear models tested associations of hormone levels and/or variation with concussion status, symptoms, and recovery, controlling for self-reported birth control use at pre-injury baseline.

RESULTS

Female participants with concussion had higher progesterone levels relative to controls on average across all visits (mean difference (MD; ln ng·mL -1 ) (standard error) = 0.26 (0.08), t (193) = 3.03, P = 0.003). Those with concussion had elevated estradiol at 24 h (MD = 0.27 (0.09), t (506) = 3.04, P = 0.02), Init RTP (MD = 0.38 (0.09), t (508) = 4.29, P < 0.001), and PRTP (MD = 0.30 (0.09), t (515) = 3.25, P = 0.01) relative to pre-injury baseline and compared with controls at Init RTP (MD = 0.35 (0.12), t (429) = 2.78, P = 0.006). Concussed participants had a lower range of estradiol over 7-28 d than controls ( B (SE) = -0.24 (0.09), F (1,145) = 6.43, P = 0.01). Acutely after concussion, estradiol was positively associated with Brief Symptom Inventory Global Severity Index scores ( B (SE) = 0.29 (0.12), F (1,102) = 5.60, P = 0.02). No significant relationships were found between hormones and recovery.

CONCLUSIONS

These results, which warrant further research, suggest that ovarian hormones may be associated with concussion and psychological symptom severity post-concussion.

A Machine Learning Model for Post-Concussion Musculoskeletal Injury Risk in Collegiate Athletes

Background

Emerging evidence indicates an elevated risk of post-concussion musculoskeletal (MSK) injuries in collegiate athletes; however, identifying athletes at highest risk remains to be elucidated.

Objective

The purpose of this study was to model post-concussion MSK injury risk in collegiate athletes by integrating a comprehensive set of variables by machine learning.

Methods

A risk model was developed and tested on a dataset of 194 athletes (155 in the training set and 39 in the test set) with 135 variables entered into the analysis, which included participant's heath and athletic history, concussion injury and recovery specific criteria, and outcomes from a diverse array of concussions assessments. The machine learning approach involved transforming variables by the Weight of Evidence method, variable selection using L1-penalized logistic regression, model selection via the Akaike Information Criterion, and a final L2-regularized logistic regression fit.

Results

A model with 48 predictive variables yielded significant predictive performance of subsequent MSK injury with an area under the curve of 0.82. Top predictors included cognitive, balance, and reaction at Baseline and Acute timepoints. At a specified false positive rate of 6.67%, the model achieves a true positive rate (sensitivity) of 79% and a precision (positive predictive value) of 95% for identifying at-risk athletes via a well calibrated composite risk score.

Conclusion

These results support the development of a sensitive and specific injury risk model using standard data combined with a novel methodological approach that may allow clinicians to target high injury risk student-athletes. The development and refinement of predictive models, incorporating machine learning and utilizing comprehensive datasets, could lead to improved identification of high-risk athletes and allow for the implementation of targeted injury risk reduction strategies by identifying student-athletes most at risk for post-concussion MSK injury.

Epigenetics of concussion: A systematic review

BACKGROUND

Concussion is the most common neurological disorder affecting millions of people globally each year. Identifying epigenetic mechanisms influencing concussion incidence, severity and recovery could provide diagnostic and prognostic insight into this injury.

OBJECTIVES

This systematic review aims to identify the epigenetic mechanisms underpinning concussion.

METHODS

Seven electronic databases; PubMed, MEDLINE, CINAHL, Cochrane library, SPORTDiscus, Scopus and Web of Science were searched for studies that investigated the epigenetic mechanisms of concussion and its underlying neuropathology.

RESULTS

Based on inclusion and exclusion criteria, 772 titles were independently analysed by two of the authors to a final list of 28 studies that totaled 3042 participants. We observed separate associations between sncRNAs, methylation, histone modification and concussion. Overall, 204 small non-coding RNAs were significantly dysregulated between concussed participants and controls or between concussion participants with no post-concussive symptoms and those with post-concussive symptoms. From these, 37 were reported in more than one study and 23 of these were expressed in a consistent direction with at least one further study. Ingenuity pathway analysis identified 10 miRNAs known to regulate 15 genes associated with human neurological pathologies. Two studies found significant changes in global methylation in concussed participants and one study found a decrease in H3K27Me3 in the context of DNA damage and concussion.

CONCLUSIONS

The review findings suggest that epigenetic mechanisms may play an important role in the pathophysiological mechanisms that could influence outcome, recovery, and potential long-term consequences of concussion for individuals.

Association between magnetic resonance imaging use and recovery time following concussion: a CARE consortium study

Researchers may implement magnetic resonance imaging (MRI) to evaluate neurophysiological metrics (e.g. connectivity) in athletes with sports-related concussion (SRC). MRI usage has been purported to exacerbate symptoms that mimic SRC symptomatology, possibly influencing recovery. The present study examined MRI use on SRC recovery outcomes in collegiate athletes. Ninety student-athletes (45 with MRI acutely post-SRC, 45 non-MRI) from four collegiate sites were analysed. Multivariable Cox proportional hazard regressions were used to measure the SRC recovery risk [return-to-play (RTP) initiation (RTP-I) and unrestricted RTP] with hazard ratios (HR) and 95% confidence intervals (95% CI). No hazard differences for median days to RTP-I [MRI: 10, interquartile range (IQR) = 7-15; non-MRI: 7 (IQR = 4-9)] were observed (HR = 0.75; 95% CI: 0.28-1.21). No hazard differences for median days to RTP [(MRI: 17 (IQR = 11-60); non-MRI: 12 (IQR = 8-24)] were observed (HR = 0.77; 95% CI: 0.29-1.26). MRI use post-SRC does not affect recovery; researchers/clinicians can employ such a procedure without affecting athlete recovery.

Factors Associated with Persisting Post-Concussion Symptoms Among Collegiate Athletes and Military Cadets: Findings from the NCAA-DoD CARE Consortium

BACKGROUND

Persisting post-concussion symptoms (PPCS) is a condition characterized by prolonged recovery from a mild traumatic brain injury (mTBI) and compromised quality of life. Previous literature, on the basis of small sample sizes, concludes that there are several risk factors for the development of PPCS.

OBJECTIVE

We seek to identify protective and risk factors for developing slow recovery or persisting post-concussion symptoms (PPCS) by analyzing medical history, contact sport level, setting, and the Sport Concussion Assessment Tool (SCAT) and Brief Symptom Inventory (BSI-18) assessments at baseline and post-injury.

PATIENTS AND METHODS

We studied 47,860 unique collegiate athletes and Military Service Academy (MSA) cadets enrolled in the 30-site National Collegiate Athletic Association and Department of Defense (NCAA-DoD) Concussion Assessment Research and Education (CARE) Consortium prospective cohort study of baseline and post-injury data from 2014 to 2019. Medical histories and preseason baselines (n = 60,720), along with SCAT and BSI-18 examinations (n = 5379) conducted within 48 h post-injury, were analyzed. PPCS is defined as cleared for return to play (RTP) > 29 days.

RESULTS

Of 5073 concussions, the median (95% CI) and mean (SD) RTP were 15.2 (4.8-82.6) days and 22.2 (23.0) days, respectively, with 891 developing PPCS. Sex, high SCAT score, high BSI-18 score, and delayed reporting produced small effect sizes on RTP (d = 0.22-0.44). Adjusted odds ratios (OR) of developing PPCS indicated the following risk factors: SCAT total score > 45 (OR = 1.91, 95% CI: 1.58-2.30), female sex (OR = 1.80, 95% CI: 1.53-2.13), concussion history (OR = 1.80, 95% CI: 1.29-2.52), and delayed reporting (OR = 1.42, 95% CI: 1.20-1.67). In contrast, protective factors against developing PPCS were: being a limited-contact (OR = 0.34, 95% CI: 0.25-0.47), noncontact (OR = 0.35, 95% CI: 0.24-0.51) or contact sport athlete (OR = 0.34, 95% CI: 0.28-0.41); and receiving the concussion at practice (OR = 0.64, 95% CI: 0.53-0.77) or in competition (OR = 0.44, 95% CI: 0.34-0.56). Athletes diagnosed with a learning disability and taking a neurostimulant were more protected than those who were not (OR = 0.44, 95% CI: 0.26-0.76 versus OR = 0.72, 95% CI: 0.49-1.05, respectively). A prognostic model using these variables offers poor sensitivity (9%) but high specificity (98%) in identifying PPCS (AUC = 0.72).

CONCLUSIONS

This study of 5073 concussions indicates that female sex, high symptom burden, and prior concussion are risk factors for slow recovery. In addition, learning disability, contact sport, and concussion in competition are protective against slow recovery. The neurostimulant results suggest that clinicians should keep their attention deficit disorder (ADD) and attention-deficit/hyperactivity disorder (ADHD) patients on their current neurostimulant medication after a concussion. A prognostic logistic regression model based on behavioral clinical findings did a poor job of identifying PPCS.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Research Letter: Relationship of Blood Biomarkers of Inflammation With Acute Concussion Symptoms and Recovery in the CARE Consortium

OBJECTIVE

Determine the association of inflammatory biomarkers with clinical measures and recovery in participants with concussion.

SETTING

Multicenter study in National Collegiate Athletic Association member institutions including military service academies.

PARTICIPANTS

Four hundred twenty-two participants with acute concussion.

DESIGN

Clinical visits and blood draws were completed preinjury and at multiple visits postconcussion (0-12 hours, 12-36 hours, and 36-60 hours postinjury). Clinical measures included Sport Concussion Assessment Tool (SCAT) symptom severity, Balance Error Scoring System, Standardized Assessment of Concussion (SAC), Brief Symptom Inventory-18 (BSI-18) scores, time to initiation of graduated return-to-play (RTP) protocol, and time to RTP. Interleukin (IL)-6, IL-10, IL-8, IL-1 receptor antagonist (RA), tumor necrosis factor (TNF), c-reactive protein, and vascular endothelial growth factor (VEGF) were measured in serum. Prespecified analyses focused on IL-6 and IL-1RA at 0 to 12 hours; exploratory analyses were conducted with false discovery rate correction.

RESULTS

For prespecified analyses, IL-1RA at 0 to 12 hours in female participants was positively associated with more errors on the SAC (B(standard error, SE) = 0.58(0.27), P < .05) and worse SCAT symptom severity (B(SE) = 0.96(0.44), P < .05). For exploratory analyses, higher levels of IL-1RA at 12 to 36 hours were associated with higher global (B(SE) = 0.55(0.14), q < 0.01), depression (B(SE) = 0.45(0.10), q < 0.005), and somatization scores on the BSI (B(SE) = 0.46(0.12), q < 0.01) in participants with concussion; Higher TNF at 12 to 36 hours was associated with fewer errors on the SAC (B(SE) = - 0.46(0.14), q < 0.05). Subanalyses showed similar results for male participants and participants who were athletes. No associations were discovered in nonathlete cadets. Higher IL-8 at 0 to 12 hours was associated with slower RTP in female participants (OR = 14.47; 95% confidence interval, 2.96-70.66, q < 0.05); no other associations with recovery were observed.

CONCLUSIONS

Peripheral inflammatory markers are associated with clinical symptoms following concussion and potentially represent one mechanism for psychological symptoms observed postinjury. Current results do not provide strong support for a potential prognostic role for these markers.

Quantitative Pupillometry Predicts Return to Play and Tracks the Clinical Evolution of Mild Traumatic Brain Injury in US Military Academy Cadets: A Military Traumatic Brain Injury Initiative Study

BACKGROUND AND OBJECTIVES

The objective of this study was to determine the utility of the pupillary light reflex use as a biomarker of mild traumatic brain injury (mTBI).

METHODS

This prospective cohort study was conducted at The US Military Academy at West Point. Cadets underwent a standard battery of tests including Balance Error Scoring System, Sports Concussion Assessment Tool Fifth Edition Symptom Survey, Standard Assessment of Concussion, and measure of pupillary responses. Cadets who sustained an mTBI during training events or sports were evaluated with the same battery of tests and pupillometry within 48 hours of the injury (T1), at the initiation of a graded return to activity protocol (T2), and at unrestricted return to activity (T3).

RESULTS

Pupillary light reflex metrics were obtained in 1300 cadets at baseline. During the study period, 68 cadets sustained mTBIs. At T1 (<48 hours), cadets manifested significant postconcussion symptoms (Sports Concussion Assessment Tool Fifth Edition P < .001), and they had decreased cognitive performance (Standardized Assessment of Concussion P < .001) and higher balance error scores (Balance Error Scoring System P < .001) in comparison with their baseline assessment (T0). The clinical parameters showed normalization at time points T2 and T3. The pupillary responses demonstrated a pattern of significant change that returned to normal for several measures, including the difference between the constricted and initial pupillary diameter (T1 P < .001, T2 P < .05), dilation velocity (T1 P < .01, T2 P < .001), and percent of pupillary constriction (T1 P < .05). In addition, a combination of dilation velocity and maximum constriction velocity demonstrates moderate prediction ability regarding who can return to duty before or after 21 days (area under the curve = 0.71, 95% CI [0.56-0.86]).

CONCLUSION

This study's findings indicate that quantitative pupillometry has the potential to assist with injury identification and prediction of symptom severity and duration.

Multifaceted concussion assessment battery: sensitivity at the expense of specificity?

OBJECTIVES

A multifaceted assessment battery is recommended for testing suspected concussed athletes; however, the individual tests have limitations and potentially may lead to false positive outcomes. Therefore, the purpose of this study was to psychometrically evaluate concussion assessment tools used for intercollegiate student-athletes, with a focus on the time interval between baseline and subsequent assessments.

METHODS

Ninety-two collegiate student-athletes matched between concussion (N = 46. F32/M14) and non-concussion (N = 46, 32F/14 M) completed the standard assessment of concussion, balance error scoring system, symptom questionnaire, and computerized neurocognitive tests at baseline and acutely (<48 h) following a concussion. Test outcomes were compared between time points with three approaches: 1) vs baseline, 2) reliable change scores (RCI), and 3) vs American College of Rehabilitation Medicine (ACRM). Concussion assessment sensitivity, specificity, likelihood ratios, predictive values, and diagnostic odds ratio were calculated. A receiver operator characteristic compared area under the curve (AUC) for the overall battery as well as between academic years.

RESULTS

The sensitivity of the battery was high (78.3-95.7%), but specificity was low to moderate (6.5-52.2%) with comparison to the RCI typically performing best. The three approaches yielded AUC values between 0.51 and 0.63 which is below the discriminatory threshold (0.70) with comparison to RCI performing best. By academic year, Juniors was the only year in which the ROC exceeded the threshold (0.75). The number of tests failed did not improve any AUC values (0.51-0.69) to exceed the threshold.

CONCLUSIONS

The outcomes of this study support the premise that concussion must be evaluated using a comprehensive clinical examination including a variety of assessments to evaluate each clinical domain. Clinicians need to recognize that the multifaceted assessment battery has high sensitivity, but the overall psychometrics do not exceed the threshold for group discrimination and caution must be used in their interpretation.

Baseline concussion assessment performance by sex in military service academy rugby players: findings from the CARE Consortium

BACKGROUND

Normative student-athlete concussion assessment data may not be appropriate for service academy members (SAMs), particularly rugby players, because of the uniqueness of their academic/military training environment. Having accurate baseline data for this population is important because of their high risk for concussion and frequent lack of assigned sports medicine professional. The primary purpose of this study was to characterise baseline performance on a concussion assessment battery, with secondary purpose to determine effect of sex and concussion history on these measures among SAM rugby players.

METHODS

601 rugby-playing SAMs (19.3±1.5 years, 37.9% female) completed baseline concussion assessments: the Sport Concussion Assessment Tool (SCAT) Symptom and Symptom Severity Checklist, Standard Assessment of Concussion (SAC) and a neuropsychological test (either ImPACT (Immediate Post Concussion Assessment and Cognitive Testing) or ANAM (Automated Neuropsychological Assessment Metrics)). Groups were compared using an independent samples t-test or Mann-Whitney U test. A 2 (sex) × 2 (concussion history) ANOVA was conducted to determine the effects of sex and concussion history on outcomes.

RESULTS

Women reported greater SCAT total symptoms (3.3 vs 2.8, p<0.001, r=0.143) and symptom severities (5.7 vs 4.3, p<0.001, r=0.139), and performed worse on ImPACT Visual Memory (79.3 vs 82.6, p=0.002, r=0.144) than men. Women performed better than men on SAC (28.0 vs 27.7, p=0.03, r=0.088), ImPACT Reaction Time Composite (0.59 vs 0.61, p=0.04, r=0.092) and ANAM Code Substitution Delayed (64.3 vs 61.5, p=0.04, d=0.433). Individuals with a history of concussion reported lower ImPACT Symptom Severity (2.6 vs 4.2, p=0.02, r=0.110). There was no interaction between concussion history and sex on outcomes.

CONCLUSIONS

These findings provide reference data for SAM rugby players on baseline assessments and to help in clinical decision-making when managing sports-related concussion in absence of baseline data.

Factors Associated With Return to Activity After Concussion Among Female Service Academy Members: Findings From the NCAA-DoD CARE Consortium

INTRODUCTION

Service academy members are at high risk for concussions as a result of participation in both sports and military-specific training activities. Approximately 17% of active duty service members are female, and they face unique challenges in achieving timely recovery from concussions. Understanding the unique characteristics affecting return to unrestricted activity (RTA) among female service academy members is imperative for the ever-growing proportion of females across the U.S. military. The goal of this analysis was to determine how specific injury and individual characteristics of concussion affect 2 RTA protocol events in female service academy members: time to protocol initiation and time to protocol completion.

MATERIALS AND METHODS

All data were collected as part of the National Collegiate Athletic Association (NCAA) and the DoD Concussion Assessment, Research and Education Consortium. We examined data from female U.S. military service academy members at the 4 U.S. Service Academy sites who sustained a concussion between Fall 2014 and Spring 2020 (N = 752). Return to unrestricted activity protocol initiation time was defined as the time from injury to when cadets were cleared to begin gradual RTA, while RTA protocol completion time was defined as the time from injury to when cadets were cleared to RTA. Multivariable Cox regression analyses were used to determine the effect of 4 characteristics on RTA event times: (1) service academy members' NCAA status (e.g., student athlete), (2) prior history of concussion, (3) reporting time of concussion, and (4) sport-related concussion (SRC) or non-SRC. Because of missing data, 520 cadets were included in the model of RTA protocol initiation and 556 were included in the model of RTA protocol completion. Chi-squared analyses assessed interactions between reporting time, NCAA status, and SRC or non-SRC.

RESULTS

Service academy members who were NCAA athletes (hazard ratio [95% CI](HR [95% CI]): 1.58 [1.32, 1.90]), immediately reported their injury (HR [95% CI]: 1.40 [1.18, 1.67]), or had an SRC (HR [95% CI]: 1.29 [1.08, 1.54]) were significantly more likely to have initiated or completed the RTA protocol on any given day post-concussion compared to those who were not NCAA athletes, delayed reporting their injury, or had a non-SRC, respectively. We observed that among those with SRCs, a greater proportion of NCAA service academy members immediately reported their injury (53.9%) compared to non-NCAA (37.3%, P < .001); there was no difference in the proportion of NCAA and non-NCAA service academy members with non-SRCs who immediately reported their injury (P = .18).

CONCLUSIONS

A greater proportion of female service academy members who sustained SRCs and were NCAA athletes reported their injuries immediately, which was associated with a greater likelihood of RTA protocol initiation and completion on any given day after injury. This may be attributable to easy and timely access to medical personnel (e.g., athletic trainers) or the presence of individuals trained in identifying concussion (e.g., coaches). Future initiatives among female service academy members should include improved access to medical care across a variety of injury settings and education on the importance of early reporting after concussion.

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

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

Symptom Exacerbation and Adverse Events During a Randomized Trial of Early-Stage Rehabilitation After Sport-Related Concussion: Safety Outcomes From the Active Rehab Study

CONTEXT

Authors of few studies have used randomized controlled trials (RCTs) to quantify clinical intervention safety of rehabilitation after sport-related concussion across sport levels.

OBJECTIVE

Describe symptom exacerbation and adverse events (AEs) associated with two concussion rehabilitation interventions.

DESIGN

Cluster RCT (NCT02988596).

SETTING

Sports medicine clinic and field settings.

PATIENTS OR OTHER PARTICIPANTS

The RCT enrolled 251 concussed athletes (median age = 20 years; female, n = 48) across 28 sites from New Zealand professional rugby (n = 31), Canadian professional football (n = 52), US/Canadian colleges (n = 128) and US high schools (n = 40).

INTERVENTIONS

Two medically supervised interventions: (1) enhanced graded exertion (EGE): international return-to-sport strategy and sport-specific activities only (EGE only, n = 119); and (2) multidimensional rehabilitation (MDR) followed by EGE: early symptom-directed exercises once symptoms were stable, followed by EGE after symptoms resolved (MDR + EGE, n = 132).

MAIN OUTCOME MEASURE(S)

Primary outcomes were intrasession total symptom severity score exacerbation and significant intersession (increase 10+ severity points) sustained total symptom severity exacerbation, each measured with the Postconcussion Symptom Scale (132 total severity points on scale). Reported AEs were also described. Activity-based rehabilitation sessions (n = 1437) were the primary analysis unit. Frequencies, proportions, medians, and interquartile ranges were calculated for outcomes by treatment group.

RESULTS

The 251 postinjury participants completed 1437 (MDR + EGE = 819, EGE only = 618) activity-based intervention sessions. A total of 110 and 105 participants contributed data (those missing had no documented session data) to at least 1 activity-based session in the MDR + EGE and EGE-only arms, respectively. Intrasession symptom exacerbations were equivalently low in MDR + EGE and EGE-only arms (MDR + EGE: 16.7%, 95% CI = 14.1%, 19.1%; EGE only: 15.7%, 95% CI = 12.8%, 18.6%). In total, 9/819 MDR + EGE sessions (0.9%) and 1/618 EGE-only sessions (0.2%) resulted in a presession to postsession symptom exacerbation beyond a 10+ severity point increase; 8/9 resolved to <10 points by the next session. Two study-related AEs (1 in each arm) were reported.

CONCLUSIONS

Participants in MDR + EGE and EGE-only activities reported equivalently low rates of symptom exacerbation.

Increased Auditory Dual Task Cost During Gait Initiation in Adult Patients With Persistent Concussion Symptoms

OBJECTIVE

To compare dual task cost (DTC) during gait initiation (GI) between a population of patients with persistent concussion symptoms (PCS) and age-matched healthy participants.

DESIGN

Cohort study.

SETTING

University research center.

PARTICIPANTS

A cohort sample including 15 participants with PCS (43.9±11.7y, 73.3% female) and 23 age-matched healthy participants (42.1±10.3y, 65.2% female) as controls.

INTERVENTIONS

Participants were tested on a single occasion where they performed 5 trials of single task and 5 trials of dual task GI with 12-camera motion capture and 3 force plates.

MAIN OUTCOME MEASURES

The dependent variables of interest were the DTC for the center of pressure (COP) displacement and velocity during the anticipatory postural adjustment (APA) phase, the COP-center of mass (COP-COM) separation, and the response accuracy during the auditory cognitive tasks.

RESULTS

There were significant group differences with worse DTC for the PCS participants in anterior (A)/posterior (P) displacement (PCS, -37.5±22.1%; Control, -9.7±39.2%; P=.016, d=0.874), APA medial (M)/lateral (L) velocity (PCS, -34.8±28.8%; Control, -17.0±40.21%; P=.041, d=0.866), and the peak COP-COM separation (PCS, -7.3±6.7%; Control, 0.6±6.5%; P=.023, d=1.200). There were no significant group differences in the APA A/P velocity (PCS, -38.8±33.1%; Control, -19.8±43.9%; P=.094), APA M/L displacement (PCS, -34.8±21.8%; Control, -10.6±25.3%; P=.313), or cognitive task performance (PCS, -2.7±10.8%; Control, -0.2±4.3%; P=.321).

CONCLUSIONS

PCS participants had greater (worse) DTC during both the planning and execution of the task, with large effect sizes (d>0.80). PCS participants also used a posture-second strategy whereby attentional resources were inappropriately allocated to the cognitive task. These deficits may challenge a patient's ability to complete activities of daily living and limit their functional independence.

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

OBJECTIVE

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

DESIGN

Descriptive epidemiology study.

SETTING

Four US service academies.

PARTICIPANTS

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

INDEPENDENT VARIABLE

Sex.

OUTCOME MEASURES

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

MAIN RESULTS

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

CONCLUSIONS

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

Global neurotrauma: A systematic review and summary of the current state of registries around the world

Neurotrauma registries (NTR) collect data on traumatic brain injuries (TBI) to advance knowledge, shape policies, and improve outcomes. This study reviews global NTRs from High-Income (HICs) and Low- and Middle-Income countries (LMICs). A systematic review was conducted using PubMed, Google Scholar, Embase, and Web of Science following PRISMA guidelines to identify relevant NTRs. Twenty-six articles were included, revealing ten different NTRs from Europe, North America, Latin America, the Middle East, and Asia. North America had the most registries at four, followed by Europe and Asia with two each, and Latin America and the Middle East with one each. The median database size was 1,734 patients (Range: 65-25,000), with the largest registry from the United States (FITBIR DB) and the smallest from Iran (NSCIR-IR). The longest data collection period was 32 years, with a mean age of 43.1 years (Range: 9.07-60.0). Males comprised 70 % of patients. Sixty-six percent of articles emphasized outcomes such as functionality, length of stay, and mortality. Key challenges identified included issues with missing data and incomplete records (n = 4), lack of standardization in data collection procedures (n = 3), staffing shortages (n = 5), lack of IT infrastructure (n = 3), and problems with reproducibility, particularly in high-income countries (n = 4). Our review highlights the need for a large-scale global NTR, addressing LMIC barriers through private-public partnerships with organized neurosurgery members.

Characterizing the Effects of Concussion and Head Impact Exposure: Design, Methods, and Participant Traits of the CARE 2.0 Study

OBJECTIVE

This article describes the design, methods, and participant characteristics of the second phase of the Concussion Assessment, Research, and Education (CARE) Consortium study ("CARE 2.0") of the effects of concussion and repetitive head impact exposure on neuropsychiatric health.

METHODS

The authors conducted a prospective multisite observational study of male and female collegiate athletes and military service academy cadets and midshipmen participating in the CARE study. Participants were assessed at three time points: undergraduate baseline (UB), before departure from university or service academy (exit), and up to 6 years following graduation (postgrad) via an online battery of brain health assessments. Participant characteristics were compared across the three time points and four levels of head impact exposure.

RESULTS

A total of 4,643 participants completed the exit assessment, and 3,981 completed the postgrad assessment. Relative to the UB assessment cohort, the exit and postgrad assessment cohorts differed with respect to the percentage of women, baseline Wechsler Test of Adult Reading scores, National Collegiate Athletic Association division category, sport contact level, and number of previous concussions. The median standardized difference across balancing variables, assessment time points, and degree of head impact exposure was 0.12 (with 90% of effect sizes ≤0.29).

CONCLUSIONS

Although there were some statistically significant differences between participants across assessments, the effect sizes were modest, and overall the data suggest that the exit and postgrad cohorts reflect the characteristics of the baseline cohort. The CARE study design and its large, richly characterized sample provide an opportunity to answer important questions about cumulative and persistent effects of concussion and repetitive head impact exposure on neuropsychiatric health.

Female Collegiate Athletes' Concussion Characteristics and Recovery Patterns: A Report from the NCAA-DoD CARE Consortium

Concussion has been described in the United States (US) collegiate student-athlete population, but female-specific findings are often underrepresented and underreported. Our study aimed to describe female collegiate student-athletes' initial injury characteristics and return to activity outcomes following concussion. Female collegiate student-athletes (n = 1393) from 30-US institutions experienced a concussion and completed standardized, multimodal concussion assessments from pre-injury through unrestricted return to play (uRTP) in this prospective, longitudinal cohort study. Initial injury presentation characteristics, assessment, and return to activity outcomes [<48-h (acute), return to learn, initiate return to play (iRTP), uRTP] were collected. We used descriptive statistics to report injury characteristics, return to activity outcomes, and post-injury assessment performance change categorization (worsened, unchanged, improved) based on change score confidence rank criteria across sport contact classifications [contact (n = 661), limited (n = 446), non-contact (n = 286)]. The median (25th to 75th percentile) days to return to learn was 6.0 (3.0-10.0), iRTP was 8.1 (4.8-13.8), and uRTP was 14.8 (9.9-24.0), but varied by contact classification. Across contact levels, the majority experienced worse SCAT total symptom severity (72.8-82.6%), ImPACT reaction time (91.2-92.6%), and BSI-18 total score (45.2-51.8%) acutely relative to baseline, but unchanged BESS total errors (58.0-60.9%), SAC total score (71.5-76.1%), and remaining ImPACT domains (50.6-66.5%). Our findings provide robust estimates of the typical female collegiate student-athlete presentation and recovery trajectory following concussion, with overall similar findings to the limited female collegiate student-athlete literature. Overall varying confidence rank classification was observed acutely. Our findings provide clinically-relevant insights for athletes, clinicians, researchers, and policymakers to inform efforts specific to females experiencing concussion.

Association of Sport Helmet Status on Concussion Presentation and Recovery in Male Collegiate Student-Athletes

Sporting helmets contain force attenuating materials which reduce traumatic head injury risk and may influence sport-related concussion (SRC) sequelae. The purpose of this study was to examine the association of sport helmet status with SRC-clinical presentation and recovery trajectories in men's collegiate athletes. Sport helmet status was based on the nature of sports being either helmeted/non-helmeted. 1070 SRCs in helmeted (HELM) sports (Men's-Football, Ice Hockey, and Lacrosse), and 399 SRCs in non-helmeted (NOHELM) sports (Men's-Basketball, Cheerleading, Cross Country/Track & Field, Diving, Gymnastics, Soccer, Swimming, Tennis, and Volleyball) were analyzed. Multivariable negative binomial regression models analyzed associations between sport helmet status and post-injury cognition, balance, and symptom severity, adjusting for covariate effects (SRC history, loss of consciousness, anterograde/retrograde amnesia, event type). Kaplan-Meier curves evaluated median days to: initiation of return to play (iRTP) protocol, and unrestricted RTP (URTP) by sport helmet status. Log-rank tests were used to evaluate differential iRTP/URTP between groups. Two independent multivariable Weibull accelerated failure time models were used to examine differential iRTP and URTP between groups, after adjusting for aforementioned covariates and symptom severity score. Overall, the median days to iRTP and URTP was 6.3 and 12.0, respectively, and was comparable across NOHELM- and HELM-SRCs. Post-injury symptom severity was lower (Score Ratio 0.90, 95%CI 0.82, 0.98), and cognitive test performance was higher (Score Ratio 1.03, 95%CI 1.02, 1.05) in NOHELM-compared to HELM-SRCs. Estimated time spent recovering to iRTP/URTP was comparable between sport helmet status groups. Findings suggest that the grouping of sports into helmeted and non-helmeted show slight differences in clinical presentation but not recovery.

Profile of brief symptom inventory-18 (BSI-18) scores in collegiate athletes: A CARE Consortium study

Objective: The goal of this study was to characterize normative scores for the Brief Symptom Inventory (BSI-18) in collegiate athletes to inform decision making about the need for psychological health services in this group. Methods: Collegiate student-athletes (N = 20,034) from 25 universities completed the BSI-18 at their preseason baseline assessment. A subgroup (n = 5,387) underwent multiple baseline assessments. Global Severity Index (GSI) scores were compared to community norms and across multiple timepoints. Results: Collegiate athletes reported significantly lower GSI scores than published community norms (p<.001). Published GSI threshold scores for "caseness", identified only 2 per 100 athletes (≥ the 98th percentile) as needing further evaluation. Using a GSI score ≥ than the cohort's 90th percentile, 11.4 per 100 athletes would merit additional evaluation. These individuals were more likely to report a history of psychiatric diagnosis (Odds ratio [95% CI] 2.745 [2.480, 3.039]), as well as ≥ 2 prior concussions (p<.001). GSI scores were not highly correlated across timepoints. Suicidal ideation was rare (n = 230; 1.15%). Conclusions: For collegiate student-athletes, published BSI-18 threshold scores identify only extreme outliers who might benefit from additional behavioral health evaluation. Alternatively, use of threshold scores ≥ the 90th percentile identifies a more realistic 11.4% of the population, with higher likelihood of prior concussion and/or psychiatric disorders.

Initial Mild Traumatic Brain Injury Characteristics and Recovery Patterns Among Females Across the United States Military Service Academies: A Report from the NCAA-DoD CARE Consortium

Mild traumatic brain injury (mTBI) has been described in the United States (US) military service academy cadet population, but female-specific characteristics and recovery outcomes are poorly characterized despite sex being a confounder. Our objective was to describe female cadets' initial characteristics, assessment performance, and return-to-activity outcomes post-mTBI. Female cadets (n = 472) from the four US military service academies who experienced a mTBI completed standardized mTBI assessments from pre-injury to acute initial injury and unrestricted return-to-duty (uRTD). Initial injury presentation characteristics (e.g., delayed symptoms, retrograde amnesia) and return-to-activity outcomes [i.e., return-to-learn, initiate return-to-duty protocol (iRTD), uRTD] were documented. Descriptive statistics summarized female cadets' injury characteristics, return-to-activity outcomes, and post-mTBI assessment performance change categorization (worsened, unchanged, improved) relative to pre-injury baseline using established change score confidence rank criteria for each assessment score. The median (interquartile range) days to return-to-learn (n = 157) was 7.0 (3.0-14.0), to iRTD (n = 412) was 14.7 (8.6-25.8), and to uRTD (n = 431) was 26.0 (17.7-41.8). The majority experienced worse SCAT total symptom severity (77.8%) and ImPACT reaction time (97.0%) acutely < 24-h versus baseline, but unchanged BESS total errors (75.2%), SAC total score (72%), BSI-18 total score (69.6%), and ImPACT verbal memory (62.3%), visual memory (58.4%), and visual motor speed (52.5%). We observed similar return-to-activity times in the present female cadet cohort relative to the existing female-specific literature. Confidence ranks categorizing post-mTBI performance were heterogenous and indicate multimodal assessments are necessary. Our findings provide clinically relevant insights to female cadets experiencing mTBI across the US service academies for stakeholders providing healthcare.

The Sport Concussion Assessment Tool: A multidimensional symptom model for detecting elevated post-concussion symptoms

Objective: Investigate whether a four-factor model of post-concussion symptoms (i.e. cognitive, physical, affective, and sleep-arousal) aids in identifying student-athletes with persistent concerns not reflected by a total symptom score. Method: Collegiate student-athletes (N = 32,066) from the Concussion Assessment Research and Education consortium completed the Sport Concussion Assessment Tool, 3rd edition Symptom Evaluation at baseline and two post-injury follow-ups (i.e. beginning RTP and 6-month). Confirmatory factor analysis was used to compare a one- and four-factor model of post-concussion symptoms. Normative reference data were compared across stratifications (e.g. sex, prior concussions, and number of pre-existing conditions) using Mann-Whitney U tests, and elevation rates (i.e. ≥ 84th percentile) for subscales and the total score were recorded. Results: The four-factor model fit well before and after injury (CFIs > .95). Greater symptom severity on the subscale and total scores was associated with female sex (ps<.001, r range: .07 to .14) and more pre-existing conditions (ps<.001, η 2 range: .01 to .04), while having more prior concussions was only related to total symptom scores (ps<.001, η 2<.01). After a concussion, a sizeable portion of student-athletes (i.e., RTP = 11.8%; 6-month = 8.3%) had subscale elevations despite no total score elevation. Physical subscale elevations at RTP were the most common (i.e., 11.9%), driven by head and neck pain. Conclusion: After a sport-related concussion, a four-factor symptom model can be used to assess persistent symptoms in collegiate student-athletes. Identifying athletes with domain-specific elevations may help clinicians identify areas for further assessment and, in some cases, personalized rehabilitation plans.

Migraine epidemiology in collegiate student-athletes: Findings from the Concussion Assessment, Research, and Education (CARE) Consortium

OBJECTIVE

This cross-sectional study evaluated de-identified data from the National Collegiate Athletic Association-Department of Defense Grand Alliance from 2014 to 2020 to determine the prevalence of migraine and migraine medication and to describe differences in migraine prevalence by sex, race, and sport.

BACKGROUND

Epidemiological studies can help identify underdiagnosed and undertreated populations. Understanding migraine prevalence in collegiate student-athletes is essential for positive healthcare outcomes including development of prevention and treatment plans.

METHODS

From a concussion baseline assessment, participant's self-reported demographics (e.g., age, sex, sport), migraine diagnosis (i.e., yes/no), and migraine medication usage (e.g., yes/no, type) determined prevalence of migraine and medication use in collegiate student-athletes.

RESULTS

Migraine was reported in 5.6% (2617/47,060; 95% confidence interval [CI] 5.4%-5.8%) of the student-athletes, with higher prevalence in females, 7.5% (1319/17,628; 95% CI 7.1%-7.9%), than males, 4.6% (1298/28,116; 95% CI 4.4%-4.9%). Medication usage was reported by 36.2% (947/2617; 95% CI 34.3%-38.0%) of individuals with migraine. Migraine reporting differed by race, with Caucasian reporting highest (5.9%; 1990/33,913; 95% CI 5.6%-6.1%) and Asian the lowest (2.7%; 55/2027; 95% CI 2.1%-3.5%). Women's sports, including golf, gymnastics, and lacrosse, and men's diving and squash had higher migraine reporting than other sports.

CONCLUSION

Caucasian females reported higher rates than other groups and sport influenced rates of migraine diagnosis.

Assessment of Sports Concussion in Female Athletes: A Role for Neuroinformatics?

Over the past decade, the intricacies of sports-related concussions among female athletes have become readily apparent. Traditional clinical methods for diagnosing concussions suffer limitations when applied to female athletes, often failing to capture subtle changes in brain structure and function. Advanced neuroinformatics techniques and machine learning models have become invaluable assets in this endeavor. While these technologies have been extensively employed in understanding concussion in male athletes, there remains a significant gap in our comprehension of their effectiveness for female athletes. With its remarkable data analysis capacity, machine learning offers a promising avenue to bridge this deficit. By harnessing the power of machine learning, researchers can link observed phenotypic neuroimaging data to sex-specific biological mechanisms, unraveling the mysteries of concussions in female athletes. Furthermore, embedding methods within machine learning enable examining brain architecture and its alterations beyond the conventional anatomical reference frame. In turn, allows researchers to gain deeper insights into the dynamics of concussions, treatment responses, and recovery processes. This paper endeavors to address the crucial issue of sex differences in multimodal neuroimaging experimental design and machine learning approaches within female athlete populations, ultimately ensuring that they receive the tailored care they require when facing the challenges of concussions. Through better data integration, feature identification, knowledge representation, validation, etc., neuroinformaticists, are ideally suited to bring clarity, context, and explainabilty to the study of sports-related head injuries in males and in females, and helping to define recovery.

Sport-Specific Recovery Trajectories for NCAA Collegiate Athletes Following Concussion

The recovery trajectories of collegiate athletes with sport-related concussion (SRC) are well characterized in contact/collision sports but are less well understood in limited contact sports with lower risk, reducing the ability of clinicians to effectively manage the return-to-play (RTP) process. The current study investigated the time to asymptomatic and RTP across a broad range of male and female collegiate sports and sought to group sports by recovery intervals. Data from the Concussion Assessment, Research and Education (CARE) Consortium included 1049 collegiate athletes who sustained a SRC while participating in game or practice/training of their primary sport. Injury setting and subsequent clinical presentation data were obtained. Survival analysis using the Cox Proportional Hazard model estimated the median recovery times for each sport. Optimal univariate K-means clustering grouped sports into recovery categories. Across all sports, median time to asymptomatic following SRC ranged from 5.9 (female basketball) to 8.6 days (male wrestling). Median RTP protocol duration ranged from 4.9 days (female volleyball) to 6.3 days (male wrestling). Median total RTP days ranged from 11.2 days (female lacrosse) to 16.9 days (male wrestling). Sport clusters based on recovery differences in time to asymptomatic (3) and RTP protocol duration (2) were identified. The findings from this study of a large sample of more than 1000 NCAA collegiate athletes with SRC show there exists ranges in recovery trajectories. Clinicians can thus manage athletes with similar guidelines, with individualized treatment and recovery plans.

Clinical Utility of Ocular Assessments in Sport-Related Concussion: A Scoping Review

Background/objectives: Ocular tools and technologies may be used in the diagnosis of sport-related concussions (SRCs), but their clinical utility can vary. The following study aimed to review the literature pertaining to the reliability and diagnostic accuracy of such assessments. Methods: The preferred reporting items for systematic reviews and meta-analysis (PRISMA) extension for scoping reviews was adhered to. Reference standard reliability (RSR ≥ 0.75) and diagnostic accuracy (RSDA ≥ 0.80) were implemented to aid interpretation. Results: In total, 5223 articles were screened using the PCC acronym (Population, Concept, Context) with 74 included in the final analysis. Assessments included the King-Devick (KD) (n = 34), vestibular-ocular motor screening (VOMs) and/or near point of convergence (NPC) (n = 25), and various alternative tools and technologies (n = 20). The KD met RSR, but RSDA beyond amateur sport was limited. NPC met RSR but did not have RSDA to identify SRCs. The VOMs had conflicting RSR for total score and did not meet RSR in its individual tests. The VOMs total score did perform well in RSDA for SRCs. No alternative tool or technology met both RSR and RSDA. Conclusion: Ocular tools are useful, rapid screening tools but should remain within a multi-modal assessment for SRCs at this time.

The Interval Between Concussions Does Not Influence Time to Asymptomatic or Return to Play: A CARE Consortium Study

INTRODUCTION

The purpose of this study was to determine if the time interval between two concussive events influences the number of days to asymptomatic status, days to return to play, or performance on common post-concussion assessments following the second concussion.

METHODS

Data from 448 collegiate athletes and service academy cadets with two concussions (time between concussions: median 295.0 days [interquartile range: 125.0-438.2]), 40.0% female) were analyzed from Concussion Assessment Research and Education (CARE) Consortium institutions between 2014 and 2020. Days between concussions was the primary predictor variable. Primary outcome measures included time to asymptomatic and time to return to play following the second concussion. Secondary outcome measures included total number of symptoms, total symptom severity, Balance Error Scoring System total score, and Standardized Assessment of Concussion total score within 48 h of their second concussion.

RESULTS

Time between concussions did not significantly contribute to the multivariate time to asymptomatic (p = 0.390), time to return to play (p = 0.859), or the secondary outcomes (p-range = 0.165-0.477) models. Time to asymptomatic (p = 0.619) or return to play (p = 0.524) did not differ between same-season and different-season concussions. Sex significantly contributed to the return to play (p = 0.005) multivariate model. Delayed symptom onset and immediate removal from play/competition significantly contributed to the total number of symptoms (p = 0.001, p = 0.014) and symptom severity (p = 0.011, p = 0.022) multivariate models.

CONCLUSION

These results suggest that in a population with a large period between injuries, the time between concussions may not be relevant to clinical recovery.

Incidence of concussion and associated risk factors in collegiate soccer: findings from the NCAA-DoD CARE consortium

This retrospective cohort study aims to examine concussion incidence rates (IR) in collegiate soccer players and compare IRs based on risk factors including sex, competition level, games/practices, history of concussion, and playing position. Collegiate soccer players were recruited (n = 2,471) from 23 institutions from the NCAA-DoD Concussion Assessment, Research, and Education (CARE) Consortium. Incidence rates for concussion per 1000 athlete exposures (AEs) were calculated across the 2015-16/2016-17 seasons. Incidence rates (IR) comparing risk factor groups were also calculated. A total of 162 concussions occurred during the study, for an IR of 0.08/1000 AEs. Females were more likely to have a concussion than males overall (IR = 1.47) and were more likely to have a concussion in games (IR = 1.42) and practices (IR = 2.91). Concussions were more likely during competition compared to practice (IR = 2.53), and less likely in Division III, compared to Divisions I and II, χ2 = 6.5, p > .05. In the concussed group, male sex was associated with 2.47 times higher odds of playing defender and 2.29 times higher odds of a collision mechanism. Results confirm previous findings that females and game exposures have higher concussion IR than males and practice exposures. Findings also supported sex differences in IRs based on exposure type, position, and mechanism.

Diffusion tensor analysis of white matter tracts is prognostic of persisting post-concussion symptoms in collegiate athletes

BACKGROUND AND OBJECTIVES

After a concussion diagnosis, the most important issue for patients and loved ones is how long it will take them to recover. The main objective of this study is to develop a prognostic model of concussion recovery. This model would benefit many patients worldwide, allowing for early treatment intervention.

METHODS

The Concussion Assessment, Research and Education (CARE) consortium study enrolled collegiate athletes from 30 sites (NCAA athletic departments and US Department of Defense service academies), 4 of which participated in the Advanced Research Core, which included diffusion-weighted MRI (dMRI) data collection. We analyzed the dMRI data of 51 injuries of concussed athletes scanned within 48 h of injury. All athletes were cleared to return-to-play by the local medical staff following a standardized, graduated protocol. The primary outcome measure is days to clearance of unrestricted return-to-play. Injuries were divided into early (return-to-play < 28 days) and late (return-to-play >= 28 days) recovery based on the return-to-play clinical records. The late recovery group meets the standard definition of Persisting Post-Concussion Symptoms (PPCS). Data were processed using automated, state-of-the-art, rigorous methods for reproducible data processing using brainlife.io. All processed data derivatives are made available at https://brainlife.io/project/63b2ecb0daffe2c2407ee3c5/dataset. The microstructural properties of 47 major white matter tracts, 5 callosal, 15 subcortical, and 148 cortical structures were mapped. Fractional Anisotropy (FA) and Mean Diffusivity (MD) were estimated for each tract and structure. Correlation analysis and Receiver Operator Characteristic (ROC) analysis were then performed to assess the association between the microstructural properties and return-to-play. Finally, a Logistic Regression binary classifier (LR-BC) was used to classify the injuries between the two recovery groups.

RESULTS

The mean FA across all white matter volume was negatively correlated with return-to-play (r = -0.38, p = 0.00001). No significant association between mean MD and return-to-play was found, neither for FA nor MD for any other structure. The mean FA of 47 white matter tracts was negatively correlated with return-to-play (rμ = -0.27; rσ = 0.08; rmin = -0.1; rmax = -0.43). Across all tracts, a large mean ROC Area Under the Curve (AUCFA) of 0.71 ± 0.09 SD was found. The top classification performance of the LR-BC was AUC = 0.90 obtained using the 16 statistically significant white matter tracts.

DISCUSSION

Utilizing a free, open-source, and automated cloud-based neuroimaging pipeline and app (https://brainlife.io/docs/tutorial/using-clairvoy/), a prognostic model has been developed, which predicts athletes at risk for slow recovery (PPCS) with an AUC=0.90, balanced accuracy = 0.89, sensitivity = 1.0, and specificity = 0.79. The small number of participants in this study (51 injuries) is a significant limitation and supports the need for future large concussion dMRI studies and focused on recovery.

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

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

Normative Values for Pupillary Light Reflex Metrics Among Healthy Service Academy Cadets

INTRODUCTION

Assessments of the pupil's response to light have long been an integral part of neurologic examinations. More recently, the pupillary light reflex (PLR) has shown promise as a potential biomarker for the diagnosis of mild traumatic brain injury. However, to date, few large-scale normative data are available for comparison and reference, particularly, in military service members. The purpose of this study was to report normative values for eight PLR measurements among healthy service academy cadets based on sex, age, sleep, race, ethnicity, anisocoria, and concussion history.

METHODS

Freshmen entering a U.S. Service Academy completed a quantitative pupillometric assessment in conjunction with baseline concussion testing. PLR measurements were conducted using a Neuroptics PLR-3000 with a 121 µW light stimulus. The device measured maximum and minimum pupil diameter (mm), latency (time to maximum pupil constriction post-light stimulus [s]), peak and average constriction velocity (mm/s), average dilation velocity (mm/s), percentage pupil constriction, and T75 (time for pupil re-dilation from minimum pupil diameter to 75% maximum diameter [s]). During baseline testing, cadets also reported concussion history (yes and no) and hours slept the night before (<5.5 and ≥5.5). Normative values for each PLR measurement were calculated as mean ± SD, percentiles, and interquartile range. Mann-Whitney U tests were used to assess differences based on sex, concussion history, ethnicity, and hours slept for each PLR measurement. Kruskall-Wallis testing was used to assess differences based on age, race, and anisocoria. Alpha was set at .05 and nonparametric effect sizes (r) were calculated for statistically significant results. Effect sizes were interpreted as no effect (r < .1), small (r ≥.1-<.3), medium (r ≥.3-<.5), or large (r ≥ .5). All procedures were reviewed and approved by the local institutional review board and the U.S. Army Human Research Protection Office before the study was conducted. Each subject provided informed consent to participate in the study before data collection.

RESULTS

Of the 1,197 participants baselined, 514 cadets (131 female; 18.91 ± 0.96 years) consented and completed a valid baseline pupillometric assessment. Eighty participants reported at least one previous concussion and participants reported an average of 5.88 ± 1.63 h slept the previous night. Mann-Whitney U results suggest females had larger initial (z = -3.240; P = .001; r = .10) and end pupil diameter (z = -3.080; P = .002; r = .10), slower average dilation velocity (z = 3.254; P = .001; r = .11) and faster T75 values (z = -3.342; P = .001; r = .11). Age, sleep, and race stratified by sex, also displayed a significant impact on specific PLR metrics with effect sizes ranging from small to medium, while ethnicity, anisocoria, and concussion history did not display an impact on PLR metrics.

CONCLUSION

This study provides the largest population-specific normative values for eight PLR measurements. Initial and end pupil diameter, dilation velocity, and the T75 metrics differed by sex; however, these differences may not be clinically significant as small effect size was detected for all metrics. Sex, age, sleep, and race may impact specific PLR metrics and are worth consideration when performing PLR assessments for mild traumatic brain injury management.

Latent Profiles of Acute Symptoms, Cognitive Performance, and Balance in Sport-Related Concussions

BACKGROUND

A sport-related concussion (SRC) is a common injury that affects multiple clinical domains such as cognition, balance, and nonspecific neurobehavioral symptoms. Although multidimensional clinical assessments of concussion are widely accepted, there remain limited empirical data on the nature and clinical utility of distinct clinical profiles identified by multimodal assessments.

PURPOSE

Our objectives were to (1) identify distinct clinical profiles discernible from acute postinjury scores on the Sport Concussion Assessment Tool (SCAT), composed of a symptom checklist, a cognitive assessment (Standardized Assessment of Concussion), and a balance assessment (Balance Error Scoring System), and (2) evaluate the clinical utility of the identified profiles by examining their association with injury characteristics, neuropsychological outcomes, and clinical management-related outcomes.

STUDY DESIGN

Cohort study (Prognosis); Level of evidence, 2.

METHODS

Up to 7 latent profiles were modeled for 1885 collegiate athletes and/or military cadets who completed the SCAT at 0 to 12 hours after an injury. Chi-square tests and general linear models were used to compare identified profiles on outcomes at 12 to 72 hours after the injury. Kaplan-Meier analysis was used to investigate associations between clinical profiles and time to return to being asymptomatic and to return to play.

RESULTS

There were 5 latent profiles retained: low impairment (65.8%), high cognitive impairment (5.4%), high balance impairment (5.8%), high symptom severity (16.4%), and global impairment (6.5%). The latent profile predicted outcomes at 12 to 72 hours in expectable ways (eg, the high balance impairment profile demonstrated worse balance at 12 to 72 hours after the injury). Time to return to being asymptomatic and to return to play were different across profiles, with the high symptom severity and global impairment profiles experiencing the longest recovery and the high balance impairment profile experiencing an intermediate-length recovery (vs low impairment profile).

CONCLUSION

An SRC is a heterogeneous injury that presents in varying ways clinically in the acute injury period and results in different recovery patterns. These data support the clinical prognostic value of diverse profiles of impairment across symptom, cognitive, and balance domains. By identifying distinct profiles of an SRC and connecting them to differing outcomes, the findings support more evidence-based use of accepted multimodal clinical assessment strategies for SRCs.

Factors Influencing Time to Return to Learn Among NCAA Student-Athletes Enrolled in the Concussion Assessment, Research, and Education (CARE) Study

PURPOSE

The aim was to describe the demographic and post-injury factors that influence time to return to learn (RTL) among student-athletes enrolled in the Concussion Assessment, Research and Education (CARE) Consortium.

METHODS

A total of 47,860 student-athletes enrolled in the National Collegiate Athletic Association-Department of Defense (NCAA-DoD) CARE Consortium study from 2014 to 2020, with 1485 sport-related concussions (SRCs) analyzed in the present dataset. Demographic and post-injury characteristics were calculated using descriptive statistics, followed by Kaplan-Meier estimates to examine median time to return to normal academic performance (i.e., RTL) by sex (male, female), baseline psychiatric conditions (depression, anxiety) and/or learning disorder, NCAA division (I, II, III), SRC history (0, 1, 2, 3+), NCAA sport category (contact, limited contact, non-contact sport), and median difference in baseline/post-injury symptom severity scores (< 21, ≥ 21). Further, a multivariable zero-inflated negative binomial (ZINB) regression model was used to examine their association with RTL.

RESULTS

Overall, time to RTL (mean = 4.96 ± 8.24 days, median = 3.0 [interquartile range = 0.0, 6.0] days) was found to be influenced by several factors resulting in earlier trajectories. Notably, nearly 25% of the sample demonstrated immediate RTL (i.e., 0 days). Among student-athletes who did not immediately RTL, males demonstrated a decreased rate in RTL (rate = 0.79; 95% CI 0.66-0.96) compared to females. Further, student-athletes with a ≥ 21 change in symptom severity score (post-injury baseline) demonstrated a higher rate of RTL (rate = 1.47; 95% CI 1.21-1.79) compared to student-athletes with a symptom severity change score < 21. Lastly, male student-athletes demonstrated two times higher odds (odds ratio = 1.95; 95% CI 1.02-3.73) of immediate RTL compared to female student-athletes. No other covariates were associated with time to RTL.

CONCLUSION

Collectively, the present findings suggest a rapid return to the classroom following concussion. Specifically, males demonstrated higher odds of time to RTL, whereas those with greater differences in symptom severity resulted in a higher rate of time to RTL among those who did not immediately RTL. Ultimately, these findings support prior work emphasizing an individualized approach to SRC management.

Optimizing baseline and post-concussion assessments through identification, confirmation, and equivalence of latent factor structures: Findings from the NCAA-DoD CARE Consortium

Objective: Concussion evaluations use a multidimensional assessment to evaluate unique patient function dimensions (e.g., subjective symptoms differ from balance assessments), but the overarching latent factor structure has not been empirically substantiated. Our objective was to determine the cumulative latent factor structure of pre-injury baseline and acute (<48-h) post-concussion assessment battery outcomes, and determine measurement equivalence among common factors in collegiate student-athletes. Methods: Collegiate student-athletes at baseline (n = 21,865) and post-concussion (n = 1,537) across 25-institutions completed standardized assessments. Individual items were used from the baseline and post-concussion assessments and consisted of: Sport Concussion Assessment Tool, Brief Symptom Inventory-18, Standardized Assessment of Concussion, Balance Error Scoring System, Immediate Post-Concussion Assessment and Cognitive Test, and vestibular-ocular motor screening. Exploratory factor analysis was used on half the baseline data, and confirmatory factor analysis on the remaining baseline data and post-concussion data separately. Measurement equivalence was assessed between sex, sport contact classification, concussion history, and time. Results: A 10-factor exploratory model was established and comprised of: depression, somatic, vestibulo-ocular, headache, postural stability, neurocognition, emotional, fatigue, cognitive, consciousness clouding. The 10-factor model was confirmed at baseline and post-concussion with strong measurement equivalence between timepoints. Strong to strict measurement equivalence was observed for sex, sport contact classification, and concussion history at both timepoints separately. Conclusion: Our findings established a robust 10-factor latent factor model equivalent across timepoints and common factors among healthy and concussed collegiate athletes. Clinicians can use these findings to target specific factors while reducing redundant elements to provide efficient, comprehensive post-concussion assessments.

Optimizing Concussion Care Seeking: Using Machine Learning to Predict Delayed Concussion Reporting

BACKGROUND

Early medical attention after concussion may minimize symptom duration and burden; however, many concussions are undiagnosed or have a delay in diagnosis after injury. Many concussion symptoms (eg, headache, dizziness) are not visible, meaning that early identification is often contingent on individuals reporting their injury to medical staff. A fundamental understanding of the types and levels of factors that explain when concussions are reported can help identify promising directions for intervention.

PURPOSE

To identify individual and institutional factors that predict immediate (vs delayed) injury reporting.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This study was a secondary analysis of data from the Concussion Assessment, Research and Education (CARE) Consortium study. The sample included 3213 collegiate athletes and military service academy cadets who were diagnosed with a concussion during the study period. Participants were from 27 civilian institutions and 3 military institutions in the United States. Machine learning techniques were used to build models predicting who would report an injury immediately after a concussive event (measured by an athletic trainer denoting the injury as being reported "immediately" or "at a delay"), including both individual athlete/cadet and institutional characteristics.

RESULTS

In the sample as a whole, combining individual factors enabled prediction of reporting immediacy, with mean accuracies between 55.8% and 62.6%, depending on classifier type and sample subset; adding institutional factors improved reporting prediction accuracies by 1 to 6 percentage points. At the individual level, injury-related altered mental status and loss of consciousness were most predictive of immediate reporting, which may be the result of observable signs leading to the injury report being externally mediated. At the institutional level, important attributes included athletic department annual revenue and ratio of athletes to athletic trainers.

CONCLUSION

Further study is needed on the pathways through which institutional decisions about resource allocation, including decisions about sports medicine staffing, may contribute to reporting immediacy. More broadly, the relatively low accuracy of the machine learning models tested suggests the importance of continued expansion in how reporting is understood and facilitated.

Association of Premorbid Anxiety and Depression Symptoms in Concussion Recovery in Collegiate Student-Athletes

BACKGROUND

Mental health disorders are linked to prolonged concussion symptoms. However, the association of premorbid anxiety/depression symptoms with postconcussion return-to-play timelines and total symptom burden is unclear.

OBJECTIVE

To examine the association of self-reported premorbid anxiety/depression symptoms in collegiate student-athletes with (1) recovery times until asymptomatic, (2) return-to-play, and (3) postconcussion symptom burden.

STUDY DESIGN

Athletes in the Concussion Assessment, Research and Education Consortium completed baseline concussion assessments (Sport Concussion Assessment Tool [SCAT3] and Brief Symptom Inventory-18 [BSI-18]). Athletes were tested postinjury at <6 hours, 24 to 48 hours, time of asymptomatic and start of return-to-play protocol, unrestricted return-to-play, and 6 months after injury. Injured athletes were categorized into 4 groups based on BSI-18 scores: (1) B-ANX, elevated anxiety symptoms only; (2) B-DEP, elevated depression symptoms only; (3) B-ANX&DEP, elevated anxiety and depression symptoms; and (4) B-NEITHER, no elevated anxiety or depression symptoms. Relationship between age, sex, BSI-18 group, SCAT3 total symptom and severity scores, and time to asymptomatic status and return-to-play was assessed with Pearson's chi-squared test and robust analysis of variance.

LEVEL OF EVIDENCE

Level 3.

RESULTS

Among 1329 athletes with 1352 concussions, no respondents had a self-reported premorbid diagnosis of anxiety/depression. There was no difference in time until asymptomatic or time until return-to-play between BSI-18 groups (P = 0.15 and P = 0.11, respectively). B-ANX, B-DEP, and B-ANX&DEP groups did not have higher total symptom or severity scores postinjury compared with the B-NEITHER group.

CONCLUSION

Baseline anxiety/depression symptoms in collegiate student-athletes without a mental health diagnosis are not associated with longer recovery times until asymptomatic, longer time to return-to-play, or higher postconcussion total symptom and severity scores compared with athletes without baseline symptoms.

CLINICAL RELEVANCE

Anxiety and depression symptoms without a clear mental health diagnosis should be considered differently from other comorbidities when discussing prolonged recovery in collegiate student-athletes.

The Prevalence and Influence of New or Worsened Neck Pain After a Sport-Related Concussion in Collegiate Athletes: A Study From the CARE Consortium

BACKGROUND

Neck pain in a concussion population is an emerging area of study that has been shown to have a negative influence on recovery. This effect has not yet been studied in collegiate athletes.

HYPOTHESIS

New or worsened neck pain is common after a concussion (>30%), negatively influences recovery, and is associated with patient sex and level of contact in sport.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Varsity-level athletes from 29 National Collegiate Athletic Association member institutions as well as nonvarsity sport athletes at military service academies were eligible for enrollment. Participants completed a preseason baseline assessment and follow-up assessments at 6 and 24 to 48 hours after a concussion, when they were symptom-free, and when they returned to unrestricted play. Data collection occurred between January 2014 and September 2018.

RESULTS

A total of 2163 injuries were studied. New or worsened neck pain was reported with 47.0% of injuries. New or worsened neck pain was associated with patient sex (higher in female athletes), an altered mental status after the injury, the mechanism of injury, and what the athlete collided with. The presence of new/worsened neck pain was associated with delayed recovery. Those with new or worsened neck pain had 11.1 days of symptoms versus 8.8 days in those without (P < .001). They were also less likely to have a resolution of self-reported symptoms in ≤7 days (P < .001). However, the mean duration of the return-to-play protocol was not significantly different for those with new or worsened neck pain (7.5 ± 7.7 days) than those without (7.4 ± 8.3 days) (P = .592).

CONCLUSION

This novel study shows that neck pain was common in collegiate athletes sustaining a concussion, was influenced by many factors, and negatively affected recovery.

Sex Differences in Recovery Trajectories of Assessments for Sport-Related Concussion Among NCAA Athletes: A CARE Consortium Study

OBJECTIVES

The purpose of this study was to determine sex differences in recovery trajectories of assessments for sport-related concussion using Concussion Assessment, Research and Education (CARE) Consortium data.

METHODS

National Collegiate Athletic Association athletes (N = 906; 61% female) from sex-comparable sports completed a pre-season baseline assessment and post-sport-related concussion assessments within 6 h of injury, 24-48 h, when they initiated their return to play progression, when they were cleared for unrestricted return to play, and 6 months post-injury. Assessments included the Standardized Assessment of Concussion, Balance Error Scoring System, Brief Symptom Inventory-18, Immediate Post-concussion Assessment and Cognitive Testing (ImPACT), Sport Concussion Assessment Tool-3 symptom evaluation, Clinical Reaction Time, King-Devick test, Vestibular Ocular Motor Screen, 12-item Short-Form Health Survey, Hospital Anxiety and Depression Scale, and Satisfaction with Life Scale.

RESULTS

Only the Vestibular Ocular Motor Screen Total Symptom Score at the 24-48 h timepoint (p = 0.005) was statistically significantly different between sexes. Specifically, female athletes (mean = 60.2, 95% confidence interval [CI] 51.5-70.4) had higher Vestibular Ocular Motor Screen Total Symptom Scores than male athletes (mean = 36.9, 95% CI 27.6-49.3), but this difference resolved by the time of return-to-play initiation (female athletes, mean = 1.8, 95% CI 1.1-2.9; male athletes, mean = 4.1, 95% CI 1.5-10.9).

CONCLUSIONS

Sport-related concussion recovery trajectories for most assessments were similar for female and male National Collegiate Athletic Association athletes except for Vestibular Ocular Motor Screen symptoms within 48 h of sport-related concussion, which was greater in female athletes. Female athletes had a greater symptom burden across all timepoints, suggesting that cross-sectional observations may indicate sex differences despite similar recovery trajectories.

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

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

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

RESULTS

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

CONCLUSION

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

Gene Expression Alterations in Peripheral Blood Following Sport-Related Concussion in a Prospective Cohort of Collegiate Athletes: A Concussion Assessment, Research and Education (CARE) Consortium Study

BACKGROUND

Molecular-based approaches to understanding concussion pathophysiology provide complex biological information that can advance concussion research and identify potential diagnostic and/or prognostic biomarkers of injury.

OBJECTIVE

The aim of this study was to identify gene expression changes in peripheral blood that are initiated following concussion and are relevant to concussion response and recovery.

METHODS

We analyzed whole blood transcriptomes in a large cohort of concussed and control collegiate athletes who were participating in the multicenter prospective cohort Concussion Assessment, Research, and Education (CARE) Consortium study. Blood samples were collected from collegiate athletes at preseason (baseline), within 6 h of concussion injury, and at four additional prescribed time points spanning 24 h to 6 months post-injury. RNA sequencing was performed on samples from 230 concussed, 130 contact control, and 102 non-contact control athletes. Differential gene expression and deconvolution analysis were performed at each time point relative to baseline.

RESULTS

Cytokine and immune response signaling pathways were activated immediately after concussion, but at later time points these pathways appeared to be suppressed relative to the contact control group. We also found that the proportion of neutrophils increased and natural killer cells decreased in the blood following concussion.

CONCLUSIONS

Transcriptome signatures in the blood reflect the known pathophysiology of concussion and may be useful for defining the immediate biological response and the time course for recovery. In addition, the identified immune response pathways and changes in immune cell type proportions following a concussion may inform future treatment strategies.

Collegiate student-athletes concussion knowledge and attitudes: what a difference a decade Makes

OBJECTIVE

The purpose of this study was to assess changes in concussion knowledge and attitudes amongst incoming intercollegiate student-athletes over the course of a decade (2010-2012 vs 2021-2023).

METHODS

There were 592 student-athletes from 2 cohorts (2010-2012, 2021-2023) who completed the Rosenbaum Concussion Knowledge and Attitudes Survey (ROCKaS) questionnaire which is comprised of a concussion knowledge index (CKI, 0-24) and attitude index (CAI, 15-75) with higher scores reflecting better performance. A three factor ANOVA (Group, Sex, Concussion History) compared performance on the CKI and CAI. Individual questions were compared between groups with a Chi-Square analysis.

RESULTS

For the CKI, there was a significant main effect for Group (2010-2012: 18.5 ± 2.6, 2021-2023: 19.4 ± 2.5, p < 0.001, η 2 = 0.032 ) . For the CAI, there was also a significant main effect for group (2010-2012: 52.9 ± 6.0, 2021-2023: 62.2 ± 6.5, p < 0.001, η 2 = 0.359 ) .

CONCLUSIONS

The results of this study show a modest increase in concussion knowledge; however, large improvements in concussion attitudes were observed between groups. These results suggest a continued improvement in student-athlete concussion awareness and provide specific areas to continue addressing persistent misconceptions.

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

CONTEXT

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

OBJECTIVES

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

DESIGN

Prospective cohort study.

SETTING

Clinical setting.

PATIENTS OR OTHER PARTICIPANTS

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

MAIN OUTCOME MEASURE(S)

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

RESULTS

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

CONCLUSIONS

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

Optimizing Concussion Care Seeking: Connecting Care-Seeking Behaviors and Neurophysiological States Through Blood Biomarkers

BACKGROUND

Timely and appropriate medical care after concussion presents a difficult public health problem. Concussion identification and treatment rely heavily on self-report, but more than half of concussions go unreported or are reported after a delay. If incomplete self-report increases exposure to harm, blood biomarkers may objectively indicate this neurobiological dysfunction.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare postconcussion biomarker levels between individuals with different previous concussion diagnosis statuses and care-seeking statuses. It was hypothesized that individuals with undiagnosed concussions and poorer care seeking would show altered biomarker profiles.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Blood samples were collected from 287 military academy cadets and collegiate athletes diagnosed with concussion in the Advanced Research Core of the Concussion Assessment, Research and Education Consortium. The authors extracted each participant's self-reported previous concussion diagnosis status (no history, all diagnosed, ≥1 undiagnosed) and whether they had delayed or immediate symptom onset, symptom reporting, and removal from activity after the incident concussion. The authors compared the following blood biomarkers associated with neural injury between previous concussion diagnosis status groups and care-seeking groups: glial fibrillary acidic protein, ubiquitin c-terminal hydrolase-L1 (UCH-L1), neurofilament light chain (NF-L), and tau protein, captured at baseline, 24 to 48 hours, asymptomatic, and 7 days after unrestricted return to activity using tests of parallel profiles.

RESULTS

The undiagnosed previous concussion group (n = 21) had higher levels of NF-L at 24- to 48-hour and asymptomatic time points relative to all diagnosed (n = 72) or no previous concussion (n = 194) groups. For those with delayed removal from activity (n = 127), UCH-L1 was lower at 7 days after return to activity than that for athletes immediately removed from activity (n = 131). No other biomarker differences were observed.

CONCLUSION

Individuals with previous undiagnosed concussions or delayed removal from activity showed some different biomarker levels after concussion and after clinical recovery, despite a lack of baseline differences. This may indicate that poorer care seeking can create neurobiological differences in the concussed brain.

Collegiate Athletes With Diabetes: Baseline Medical Comorbidities and Preseason Concussion Testing Performance

CONTEXT

People with diabetes mellitus (DM) are at increased risk for adverse health events and complications throughout their lifetime. Whether DM significantly affects collegiate athletes' concussion baseline testing performance remains unclear.

OBJECTIVES

To (1) describe the prevalence of DM and associated comorbidities and (2) compare concussion baseline testing performance between student-athletes with DM and student-athletes without DM (NoDM).

DESIGN

Retrospective, cross-sectional study.

SETTING

University.

PATIENTS OR OTHER PARTICIPANTS

Using the Concussion, Assessment, Research and Education (CARE) Consortium research database, we matched athletes with self-reported DM (N = 229) by institution, sex, age, sport, position, testing year, and concussion history to athletes with NoDM (N = 229; total sample mean age = 19.6 ± 1.4 years, women = 42%).

MAIN OUTCOME MEASURE(S)

Descriptive statistics and χ2 tests of independence with subsequent odds ratios were calculated. Independent-samples t tests compared baseline symptoms, neurocognitive testing, and balance performance between athletes with DM and athletes with NoDM. Effect sizes were determined for significant group differences.

RESULTS

At baseline, athletes with DM had higher rates of self-reported pre-existing balance disorders, sleep disorders, seizure disorders, motion sickness, learning disorders, vision and hearing problems, psychiatric disorders, depression, bipolar disorder, nonmigraine headaches, and meningitis than athletes with NoDM (P values < .05). We found balance differences between groups (P = .032, Cohen d = 0.17) such that, on average, athletes with DM had 1 additional error on the Balance Error Scoring System (DM = 13.4 ± 6.5; NoDM = 12.1 ± 5.9). No other comparisons yielded significant results.

CONCLUSIONS

Although athletes with DM had high rates of self-reported balance disorders, sleep disorders, seizures, and meningitis, their baseline neurocognitive testing results were largely identical to those of athletes with NoDM. Our findings suggested that nonclinically meaningful differences were present in concussion baseline balance testing but no significant differences were noted in cognitive testing; however, the effect of DM on concussion recovery remains unknown.

Placing the keystone: the LIMBIC Military and Tactical Athlete Research Study

OBJECTIVE

The LIMBIC Military and Tactical Athletic Research Study (MATARS) framework was established to confirm and extend understanding of concussion with initial studies driven by clinical data collected between 2015 and 2020 in a collegiate sports setting. The LIMBIC MATARS framework will be leveraged to apply gold-standard and innovative research designs to advance the science of concussion. This manuscript provides the background, methodology, and initial demographic data associated with the LIMBIC MATARS.

METHODS

Consensus-based common data elements were used to conduct a retrospective chart review, specific to collegiate athletes diagnosed with concussions between 2015 and 2020 at 11 universities.

RESULTS

A final sample of 1,311 (47.8% female) concussions were diagnosed during the five-year study period from athletes participating in a variety of National Collegiate Athlete Association (NCAA) sports. The LIMBIC MATARS demographic data, align with the NCAA and other pioneering multi-site concussion-related studies in terms of biological sex, race and ethnicity, and sport participation.

CONCLUSION

This pragmatic, methodological approach was used to address several a priori hypotheses related to concussion, align with other multi-site studies of concussion, and establish a consortium for future investigations.

The Convergent Validity of the SWAY Balance Application to Assess Postural Stability in Military Cadets Recovering from Concussion

Background

Concussions are often accompanied by balance disturbances. Clinically accurate evaluation systems are often expensive, large, and inaccessible to most clinicians. The Sway Balance Mobile Application (SWAY) is an accessible method to quantify balance changes.

Purpose

To determine the known groups and convergent validity of the SWAY to assess balance after a concussion.

Study Design

Case-Control Study.

Methods

Twenty participants with acute concussion and twenty controls were recruited. At initial, one-week, and final return to activity (RTA) evaluations, all participants completed the Sports Concussion Assessment Tool (SCAT-5), and balance control measured by SWAY mBESS and NeuroCom Balance Master Sensory Organization Test (SOT). Mixed model ANOVAs were used to detect differences in SWAY mBESS and NeuroCom SOT scores with time (initial, one-week, final RTA) as the within-subjects factor and group (concussed, healthy) as the between-subjects factor. Spearman's Rho correlations explored the associations between NeuroCom SOT scores, SWAY scores, SCAT-5 symptom scores, and time in days to final RTA.

Results

The sampled population was predominantly male and age (20 ± 1), and BMI differences were insignificant between groups. The SWAY did not detect differences between healthy and concussed participants and did not detect change over time [F(2,40) = .114, p = 0.89; F(2,40)= .276, p =0.60]. When assessing the relationship between the SWAY and the SOT, no correlation was found at any time point (r = -0.317 to -0.062, p > 0.05). Time to RTA demonstrated a moderate correlation with both SCAT-5 symptom severity score (r = .693, p < 0.01) and SCAT-5 total symptom score (r = .611, p < 0.01) at the one-week follow-up.

Conclusion

The SWAY mBESS does not appear to be a valid balance assessment for the concussed patient. The SWAY mBESS in patients with concussion failed to demonstrate convergent validity and did not demonstrate an ability to validate known groups. When assessing the time to final RTA, the one-week post-initial assessment SCAT-5 symptom severity and total scores may help determine the length of recovery in this population.

Level of Evidence

Level 3.

Association of Blood Biomarkers of Inflammation With Acute Concussion in Collegiate Athletes and Military Service Academy Cadets

BACKGROUND AND OBJECTIVES

The objective was to characterize the acute effects of concussion (a subset of mild traumatic brain injury) on serum interleukin (IL)-6 and IL-1 receptor antagonist (RA) and 5 additional inflammatory markers in athletes and military service academy members from the Concussion Assessment, Research, and Education Consortium and to determine whether these markers aid in discrimination of concussed participants from controls.

METHODS

Athletes and cadets with concussion and matched controls provided blood at baseline and postinjury visits between January 2015 and March 2020. Linear models investigated changes in inflammatory markers measured using Meso Scale Discovery assays across time points (baseline and 0-12, 12-36, 36-60 hours). Subanalyses were conducted in participants split by sex and injury population. Logistic regression analyses tested whether acute levels of IL-6 and IL-1RA improved discrimination of concussed participants relative to brain injury markers (glial fibrillary acidic protein, tau, neurofilament light, ubiquitin c-terminal hydrolase-L1) or clinical data (Sport Concussion Assessment Tool-Third Edition, Standardized Assessment of Concussion, Balance Error Scoring System).

RESULTS

Participants with concussion (total, N = 422) had elevated IL-6 and IL-1RA at 0-12 hours vs controls (n = 345; IL-6: mean difference [MD] (standard error) = 0.701 (0.091), p < 0.0001; IL-1RA: MD = 0.283 (0.042), p < 0.0001) and relative to baseline (IL-6: MD = 0.656 (0.078), p < 0.0001; IL-1RA: MD = 0.242 (0.038), p < 0.0001), 12-36 hours (IL-6: MD = 0.609 (0.086), p < 0.0001; IL-1RA: MD = 0.322 (0.041), p < 0.0001), and 36-60 hours (IL-6: MD = 0.818 (0.084), p < 0.0001; IL-1RA: MD = 0.317 (0.040), p < 0.0001). IL-6 and IL-1RA were elevated in participants with sport (IL-6: MD = 0.748 (0.115), p < 0.0001; IL-1RA: MD = 0.304 (0.055), p < 0.0001) and combative-related concussions (IL-6: MD = 0.583 (0.178), p = 0.001; IL-1RA: MD = 0.312 (0.081), p = 0.0001). IL-6 was elevated in male (MD = 0.734 (0.105), p < 0.0001) and female participants (MD = 0.600 (0.177), p = 0.0008); IL-1RA was only elevated in male participants (MD = 0.356 (0.047), p < 0.0001). Logistic regression showed the inclusion of IL-6 and IL-1RA at 0-12 hours improved the discrimination of participants with concussion from controls relative to brain injury markers (χ2(2) = 17.855, p = 0.0001; area under the receiver operating characteristic curve [AUC] 0.73 [0.66-0.80] to 0.78 [0.71-0.84]), objective clinical measures (balance and cognition; χ2(2) = 40.661, p < 0.0001; AUC 0.81 [0.76-0.86] to 0.87 [0.83-0.91]), and objective and subjective measures combined (χ2(2) = 13.456, p = 0.001; AUC 0.97 [0.95-0.99] to 0.98 [0.96-0.99]), although improvement in AUC was only significantly relative to objective clinical measures.

DISCUSSION

IL-6 and IL-1RA (male participants only) are elevated in the early-acute window postconcussion and may aid in diagnostic decisions beyond traditional blood markers and common clinical measures. IL-1RA results highlight sex differences in the immune response to concussion which should be considered in future biomarker work.

Integrative data analysis to identify persistent post-concussion deficits and subsequent musculoskeletal injury risk: project structure and methods

Concussions are a serious public health problem, with significant healthcare costs and risks. One of the most serious complications of concussions is an increased risk of subsequent musculoskeletal injuries (MSKI). However, there is currently no reliable way to identify which individuals are at highest risk for post-concussion MSKIs. This study proposes a novel data analysis strategy for developing a clinically feasible risk score for post-concussion MSKIs in student-athletes. The data set consists of one-time tests (eg, mental health questionnaires), relevant information on demographics, health history (including details regarding the concussion such as day of the year and time lost) and athletic participation (current sport and contact level) that were collected at a single time point as well as multiple time points (baseline and follow-up time points after the concussion) of the clinical assessments (ie, cognitive, postural stability, reaction time and vestibular and ocular motor testing). The follow-up time point measurements were treated as individual variables and as differences from the baseline. Our approach used a weight-of-evidence (WoE) transformation to handle missing data and variable heterogeneity and machine learning methods for variable selection and model fitting. We applied a training-testing sample splitting scheme and performed variable preprocessing with the WoE transformation. Then, machine learning methods were applied to predict the MSKI indicator prediction, thereby constructing a composite risk score for the training-testing sample. This methodology demonstrates the potential of using machine learning methods to improve the accuracy and interpretability of risk scores for MSKI.

Does prior concussion lead to biomechanical alterations associated with lateral ankle sprain and anterior cruciate ligament injury? A systematic review and meta-analysis

OBJECTIVE

To determine whether individuals with a prior concussion exhibit biomechanical alterations in balance, gait and jump-landing tasks with and without cognitive demands that are associated with risk of lateral ankle sprain (LAS) and anterior cruciate ligament (ACL) injury.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Five electronic databases (Web of Science, Scopus, PubMed, SPORTDiscus and CiNAHL) were searched in April 2023.

ELIGIBILITY CRITERIA

Included studies involved (1) concussed participants, (2) outcome measures of spatiotemporal, kinematic or kinetic data and (3) a comparison or the data necessary to compare biomechanical variables between individuals with and without concussion history or before and after a concussion.

RESULTS

Twenty-seven studies were included involving 1544 participants (concussion group (n=757); non-concussion group (n=787)). Individuals with a recent concussion history (within 2 months) had decreased postural stability (g=0.34, 95% CI 0.20 to 0.49, p<0.001) and slower locomotion-related performance (g=0.26, 95% CI 0.11 to 0.41, p<0.001), both of which are associated with LAS injury risk. Furthermore, alterations in frontal plane kinetics (g=0.41, 95% CI 0.03 to 0.79, p=0.033) and sagittal plane kinematics (g=0.30, 95% CI 0.11 to 0.50, p=0.002) were observed in individuals approximately 2 years following concussion, both of which are associated with ACL injury risk. The moderator analyses indicated cognitive demands (ie, working memory, inhibitory control tasks) affected frontal plane kinematics (p=0.009), but not sagittal plane kinematics and locomotion-related performance, between the concussion and non-concussion groups.

CONCLUSION

Following a recent concussion, individuals display decreased postural stability and slower locomotion-related performance, both of which are associated with LAS injury risk. Moreover, individuals within 2 years following a concussion also adopt a more erect landing posture with greater knee internal adduction moment, both of which are associated with ACL injury risk. While adding cognitive demands to jump-landing tasks affected frontal plane kinematics during landing, the altered movement patterns in locomotion and sagittal plane kinematics postconcussion persisted regardless of additional cognitive demands.

PROSPERO REGISTRATION NUMBER

CRD42021248916.

Intersection of Race and Socioeconomic Status on Concussion Recovery among NCAA Student-Athletes: A CARE Consortium Study

PURPOSE

The objectives of this study are to 1) describe collegiate student-athlete (SA) race and household income and 2) evaluate time to normal academic performance (i.e., return to learn (RTL)), initiation of the return to play (iRTP) protocol, RTP protocol duration, and time to unrestricted RTP (URTP) after sustaining sport-related concussion (SRC).

METHODS

Data were collected between 2014 and 2020 by the Concussion Assessment, Research, and Education Consortium. Baseline data were used to characterize participant demographics ( N = 22,819) and post-SRC outcomes ( n = 5485 SRC) in time to RTL ( n = 1724) and RTP outcomes ( n = 2646) by race. Descriptive statistics and nonparametric tests examined differences across race by demographic and injury characteristics. Kaplan-Meier curves estimated median days to RTL, iRTP protocol, RTP protocol completion, and URTP by race and covariate measures. Multivariable Cox proportional hazards regression assessed the effect of race on risk of RTL and RTP recovery time points.

RESULTS

SA largely identified as White (75%) followed by Black (14%), multiracial (7%), and Asian (3%). More than half (53%) of all SA reported a household income of >$120,000, whereas 41% of Black SA reported a household income <$60,000. Race was not associated with relative risk of RTL or iRTP but was associated with RTP protocol completion and URTP. Non-Black/non-White SA were 17% less likely (adjusted hazard ratio = 0.83; 95% confidence interval = 0.71, 0.97) to complete the RTP protocol, and Black SA were 17% more likely (adjusted hazard ratio = 1.17; 95% confidence interval = 1.05, 1.31) to reach the URTP time point compared with White SA.

CONCLUSIONS

The present findings suggest collegiate SA enrolled in the Concussion Assessment, Research, and Education Consortium are primarily White and come from household incomes well above the US median. Race was not associated with RTL or iRTP but was associated with RTP protocol duration and total time to URTP. Clinicians should be conscientious of how their implicit or preconceived biases may influence SRC management among National Collegiate Athletic Association SA.