Role of biomarkers and emerging technologies in defining and assessing neurobiological recovery after sport-related concussion: a systematic review

Sport-Related Concussions in High School Athletes: A Comprehensive Update

PURPOSE OF REVIEW

Sport-related concussions (SRC) in high school athletes are a growing public health concern, with recent advancements in epidemiology, pathophysiology, diagnosis, management, and prevention. We concisely summarize SRC in high school athletes, emphasizing current research and clinical implications.

RECENT FINDINGS

Athletes are at significant risk of SRCs, with incidence varying by sport, sex, and competitive setting. Advances in pathophysiology highlight the role of metabolic disruption, inflammation, and axonal injury. Updated diagnostic tools, such as SCAT6, aid clinical evaluation, while advanced neuroimaging and biomarkers remain investigational. Return-to-sport/learn protocols emphasize a gradual, stepwise return. Preventative measures, including policy changes, neuromuscular training, and protective equipment, have reduced SRC incidence. Comprehensive SRC management includes recognition and removal from play followed by a structured return to sport/learning. Future research directions include biomarker validation, optimized prevention strategies, and long-term outcome assessment to reduce the burden of SRC in adolescent athletes.

Post-Concussion Brain Changes Relative to Pre-Injury White Matter and Cerebral Blood Flow: A Prospective Observational Study

BACKGROUND AND OBJECTIVES

Medical clearance for return to play (RTP) after sports-related concussion is based on clinical assessment. It is unknown whether brain physiology has entirely returned to preinjury baseline at the time of clearance. In this longitudinal study, we assessed whether concussed individuals show functional and structural MRI brain changes relative to preinjury levels that persist beyond medical clearance. Secondary objectives were to test whether postconcussion changes exceed uninjured brain variability and to correlate MRI findings with clinical recovery time.

METHODS

For this prospective observational study, healthy athletes without a history of psychiatric, neurologic, or sensory-motor conditions were recruited from a single university sport medicine clinic. Clinical and MRI data were collected at preseason baseline, and those who were later concussed were reassessed at 1-7 days after injury, RTP, 1-3 months after RTP, and 1 year after RTP. A demographically matched control cohort of uninjured athletes was also reassessed at their subsequent preseason baseline. Primary outcomes were postconcussion changes in MRI measures of cerebral blood flow (CBF), white matter mean diffusivity (MD), and fractional anisotropy (FA), evaluated using mixed models. Secondary outcomes were group differences in MRI change scores and correlations of change scores with days to RTP.

RESULTS

Of the 187 athletes enrolled in the study, 25 had concussion with follow-up imaging (20.3 ± 1.5 years, 56% male, 44% female) and were compared with 27 controls (19.7 ± 1.8 years, 44% male, 56% female). Concussed athletes showed statistically significant changes from baseline, including decreased frontoinsular CBF (mean and 95% CI -8.97 [-12.80, -5.01] mL/100 g/minute, z = -4.53), along with increased MD (1.94 × 10-5 [1.26, 2.69] × 10-5, z = 5.48) and reduced FA (-7.30 × 10-3 [-9.80, -5.05] × 10-3, z = -6.07) in the corona radiata and internal capsule. Effects persisted beyond RTP, although only CBF changes exceeded longitudinal variability in controls. For participants with longer recovery periods, significantly greater changes in medial temporal CBF were also seen (ρ = 0.64 [0.44, 0.81], z = 6.80).

DISCUSSION

This study provides direct evidence of persistent postconcussion changes in CBF and white matter at RTP and up to 1 year later. These results support incomplete recovery of brain physiology at medical clearance, with secondary analyses emphasizing the sensitivity of CBF to clinical recovery.

Test-Retest Reliability and Reliable Change Estimates for Sensorimotor Concussion Assessments in Healthy Young Adults

CONTEXT

Sensorimotor impairments are common sequela following concussion, but recovery following a concussion is often determined through examiner scored clinical testing. There are emerging technologies that provide objective methods to determine physiological impairment after concussion, but the psychometrics of these tools are lacking and must be established for use in clinical practice.

OBJECTIVE

The purpose of this study was to examine the test-retest reliability and provide reliable change estimates in healthy young adults for outcomes from 3 emerging technologies providing objective assessments of sensorimotor function in healthy young adults.

DESIGN

Test-retest reliability design in a laboratory setting.

METHODS

Healthy, young adults completed testing at 2 time points 4 weeks apart on the Bertec Vision Trainer, the Concussion Balance Test (COBALT), and the Neurolign Dx-100 eye-tracking system. We determined test-retest reliability using intraclass correlation coefficients with a 2-way mixed-effects model absolute agreement. Reliable change estimates were calculated for 70%, 80%, 90%, and 95% CIs.

RESULTS

Participants included 30 healthy young adults (age = 25 [5] y, interquartile range = 20-29; range = 18-38; 17% [57%] women). Test-retest reliability for the Bertec Vision Trainer outcomes ranged from 0.56 to 0.88, with 45% of the outcomes being classified as clinically acceptable (>.70 intraclass correlation coefficients ); for COBALT conditions, sway velocity ranged from 0.50 to 0.95, 95% ellipse area ranged from -0.22 to 0.88, and Sway Score ranged from 0.07 to 0.85, with 50% of COBALT metrics being clinically acceptable; and for the Dx-100, outcomes ranged from -0.20 to 0.89, with 52% being clinically acceptable.

CONCLUSIONS

Overall, test-retest reliability was moderate-to-good for the Bertec Vision Trainer assessment outcomes but were highly variable for outcomes of postural control using the COBALT and eye-tracking metrics using the Dx-100. This study adds clinically relevant test-retest reliability and reliable change estimates in healthy adults for 3 commercially available sensorimotor assessments.

The effect of assessor expertise on reliability of analysis of video signs associated with concussion in Australian football

OBJECTIVES

To determine whether spotters with medical training and experience in managing concussion have higher inter-rater reliability and accuracy than non-medical personnel when identifying video signs associated with concussion in Australian football.

DESIGN

Retrospective cohort study.

METHODS

Video clips were collected of all impacts potentially resulting in concussion during 2012 and 2013 Australian Football League (AFL) seasons. Raters were divided into medical doctors and a non-medical group comprising allied health practitioners (physiotherapists) and non-medical/non-allied health personnel (performance analysts). Raters assessed 102 randomly selected videos for signs of concussion. The inter-rater reliability was calculated. Sensitivity, specificity, positive and negative predictive values were calculated by comparing the rater responses to the consensus opinion from two highly experienced clinicians with expertise in concussion.

RESULTS

No statistically significant difference in inter-rater reliability was observed between the medical doctors and the non-medical group. Both groups demonstrated good to excellent agreement for slow to get up, clutching at head/face and facial injury. Both groups displayed intra-class coefficient >0.55 for no protective action-floppy, loss of responsiveness, and motor incoordination, and displayed lowest agreement for no protective action-tonic posturing, impact seizure and blank/vacant look. No statistically significant difference was found between the groups for sensitivity, specificity, positive and negative predictive values for correctly classifying video signs compared to the expert consensus opinion.

CONCLUSIONS

After completing sufficient standardised training and testing, medical and non-medical personnel demonstrate comparable reliability in identifying video signs of concussion in professional Australian football and may be suitable for the role of video spotter.

Prevailing theories describing sports-related concussion symptom reporting intent and behavior among adolescent athletes: a scoping review

Diagnosis of sports-related concussion (SRC) primarily relies on an athlete's self-report of injury and associated symptoms. Social pressures and attitudes surrounding SRC influence athlete reporting behavior. Unfortunately, underreporting of SRC symptoms is an issue among adolescent athletes. Nondisclosure of SRC symptoms may lead to premature return-to-play and potential persistent symptoms. This scoping review summarizes prevailing theories that explain SRC symptom reporting intent and behavior among adolescent athletes. Literature was reviewed following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) extension for Scoping Review guidelines. Inter-rater reliability was calculated at each stage. Thirty-four articles published between 2013-2024 were included. Inter-rater reliability was fair to perfect across all review stages. Of the 16 unique theories described, the Theory of Reasoned Action/Theory of Planned Behavior (TRA/TPB) was the most frequently cited theory explaining SRC symptom reporting behavior. Although the TRA/TPB framework was useful when predicting SRC symptom reporting intent, it did not adequately predict reporting behavior, consistent with the broader health behavior literature which has established that intention is not a good predictor of behavior. In light of these findings, new frameworks must be considered that consider neurodevelopmental, cognitive, and cultural factors, as these may be more useful for understanding SRC symptom reporting behavior in adolescence.

Concussion and executive functions in combat sports: A systematic review

Concussion is a diagnosis given due to trauma caused by abrupt acceleration and deceleration of the brain. The consequences involve, among others, impairments in executive functions. Considering the high incidence of concussions in combat sports, this study investigated the impacts of this trauma on core executive functions. A systematic search was carried out until November 2023, using the PRISMA method on the Virtual Health Library (BVS), PubMed, Science Direct and Scielo platforms. 11 studies, including case studies and quantitative empirical studies, met the eligibility criteria. Risk of bias was assessed using the Cochrane Collaboration risk of bias measurement tool. The results produced high and low bias studies, evaluated by three independent evaluators. Of the 11 studies selected, 91% included samples of boxers and 27.3% included mixed samples (men and women). The total sample was 1,130, aged between 15 and 68 years. 81.9% indicate impairment of executive functions in fighters, with impacts most frequently reported on memory (36.5%) and inhibitory control (27.5%). The results suggest that concussion impairs executive functions in boxing and MMA. However, more studies are needed to relate the diagnosis of concussion to possible deficits in executive functions in combat sports.

Fluid biomarkers of chronic traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of long-term disability across the world. Evidence for the usefulness of imaging and fluid biomarkers to predict outcomes and screen for the need to monitor complications in the acute stage is steadily increasing. Still, many people experience symptoms such as fatigue and cognitive and motor dysfunction in the chronic phase of TBI, where objective assessments for brain injury are lacking. Consensus criteria for traumatic encephalopathy syndrome, a clinical syndrome possibly associated with the neurodegenerative disease chronic traumatic encephalopathy, which is commonly associated with sports concussion, have been defined only recently. However, these criteria do not fit all individuals living with chronic consequences of TBI. The pathophysiology of chronic TBI shares many similarities with other neurodegenerative and neuroinflammatory conditions, such as Alzheimer disease. As with Alzheimer disease, advancements in fluid biomarkers represent one of the most promising paths for unravelling the chain of pathophysiological events to enable discrimination between these conditions and, with time, provide prediction modelling and therapeutic end points. This Review summarizes fluid biomarker findings in the chronic phase of TBI (≥6 months after injury) that demonstrate the involvement of inflammation, glial biology and neurodegeneration in the long-term complications of TBI. We explore how the biomarkers associate with outcome and imaging findings and aim to establish mechanistic differences in biomarker patterns between types of chronic TBI and other neurodegenerative conditions. Finally, current limitations and areas of priority for future fluid biomarker research are highlighted.

Perceptual Response Training for Reduction of Injury Risk Among High School Girls' Soccer Players

Background/Objectives: Neural processes involved in visual detection, decision-making, and motor plan execution are believed to play a key role in the avoidance of sport-related injuries, but very little evidence exists to guide the development of training activities for the optimization of brain function. Immersive virtual reality provides a means to precisely measure the amount of time that elapses from visual stimulus presentation to the initiation of a motor response (i.e., perceptual latency) or its completion (i.e., response time). Methods: The median value of a metric quantifying both the speed and accuracy (i.e., the rate correct per second of response time) of 50 high school female soccer players was used to assign those who exhibited suboptimal performance to a training program. Training sessions required less than 5 min and the number of sessions completed over a 7-week period ranged from 3 to 13 (median = 5). Results: Among 42 players available for follow-up assessment at 8 weeks after the first practice session (training n = 19; comparison n = 23), the results of regression-discontinuity analyses demonstrated statistically significant differences (p < 0.05) for metrics representing fast/accurate movement initiation (i.e., the rate correct score for perceptual latency, p = 0.016) and across-trial consistency (i.e., perceptual latency variability, p = 0.027). From the first practice session to the end of the soccer season, 12 injuries were sustained by 10 players (four concussions and eight musculoskeletal injuries). A time-to-event analysis demonstrated strong associations with perceptual latency variability ≥ 0.143 (Hazard Ratio = 15.43, p = 0.011) and a lifetime history of at least one concussion (Hazard Ratio = 8.84, p = 0.008). Conclusions: The strong association of movement initiation consistency with the avoidance of concussion or musculoskeletal injury suggests that the training program may have a highly beneficial far-transfer effect.

Plasma Biomarkers of Traumatic Brain Injury in Adolescents With Sport-Related Concussion

Importance

Blood-based biomarkers may clarify underlying neuropathology and potentially assist in clinical management of adolescents with sport-related concussion (SRC).

Objective

To investigate the association between SRC and plasma biomarkers in adolescents.

Design, Setting, and Participants

Prospective cohort study in Canadian sport and clinic settings (Surveillance in High Schools and Community Sport to Reduce Concussions and Their Consequences study; September 2019 to November 2022). Participants were a convenience sample of 849 adolescent (ages 10-18 years) sport participants with blood samples. Data were analyzed from February to September 2023.

Exposures

Blood collection and clinical testing preseason (uninjured) and post-SRC follow-ups (ie, ≤72 hours, 1 week, and biweekly until medical clearance to return to play [RTP]).

Main Outcomes and Measures

Plasma glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase-L1 (UCH-L1), neurofilament light (NfL), and total tau (t-tau) were assayed. Group-level comparisons of biomarker levels were conducted between uninjured and post-SRC intervals (postinjury day [PID] 0-3, 4-10, 11-28, and >28) considering age and sex as modifiers. Secondary analyses explored associations between biomarker concentrations and clinical outcomes (Sport Concussion Assessment Tool, Fifth Edition [SCAT5] symptom scores and time to RTP).

Results

This study included 1023 plasma specimens from 695 uninjured participants (467 male participants [67.2%]; median [IQR] age, 15.90 [15.13-16.84] years) and 154 participants with concussion (78 male participants [51.0%]; median [IQR] age, 16.12 [15.31-17.11] years). Acute (PID 0-3) differences relative to uninjured levels were found for GFAP (female participants: 17.8% increase; β = 0.164; 95% CI, 0.064 to 0.263; P = .001; male participants: 17.1% increase; β = 0.157; 95% CI, 0.086 to 0.229; P < .001), UCH-L1 (female participants: 43.4% increase; β = 0.361; 95% CI, 0.125 to 0.596; P = .003), NfL (male participants: 19.0% increase; β = 0.174; 95% CI, 0.087 to 0.261; P < .001), and t-tau (female participants: -22.9%; β = -0.260; 95% CI, -0.391 to -0.130; P < .001; male participants: -18.4%; β = -0.203; 95% CI, -0.300 to -0.106; P < .001). Differences were observed for all biomarkers at PID 4 to 10, 11 to 28, and greater than 28 compared with uninjured groups. GFAP, NfL, and t-tau were associated with SCAT5 symptom scores across several PID intervals. Higher GFAP after 28 days post-SRC was associated with earlier clearance to RTP (hazard ratio, 4.78; 95% CI, 1.59 to 14.31; P = .01). Male participants exhibited lower GFAP (-9.7%), but higher UCH-L1 (21.3%) compared with female participants. Age was associated with lower GFAP (-5.4% per year) and t-tau (-5.3% per year).

Conclusions and Relevance

In this cohort study of 849 adolescents, plasma biomarkers differed between uninjured participants and those with concussions, supporting their continued use to understand concussion neuropathology. Age and sex are critical considerations as these biomarkers progress toward clinical validation.

Biomarkers of Neurobiologic Recovery in Adults With Sport-Related Concussion

Importance

Sport-related concussion (SRC), a form of mild traumatic brain injury, is a prevalent occurrence in collision sports. There are no well-established approaches for tracking neurobiologic recovery after SRC.

Objective

To examine the levels of serum glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) in Australian football athletes who experience SRC.

Design, Setting, and Participants

A cohort study recruiting from April 10, 2021, to September 17, 2022, was conducted through the Victorian Amateur Football Association, Melbourne, Australia. Participants included adult Australian football players with or without SRC. Data analysis was performed from May 26, 2023, to March 27, 2024.

Exposure

Sport-related concussion, defined as at least 1 observable sign and/or 2 or more symptoms.

Main Outcomes and Measures

Primary outcomes were serum GFAP and NfL levels at 24 hours, and 1, 2, 4, 6, 8, 12, and 26 weeks. Secondary outcomes were symptoms, cognitive performance, and return to training times.

Results

Eighty-one individuals with SRC (median age, 22.8 [IQR, 21.3-26.0] years; 89% male) and 56 control individuals (median age, 24.6 [IQR, 22.4-27.3] years; 96% male) completed a total of 945 of 1057 eligible testing sessions. Compared with control participants, those with SRC exhibited higher GFAP levels at 24 hours (mean difference [MD] in natural log, pg/mL, 0.66 [95% CI, 0.50-0.82]) and 4 weeks (MD, 0.17 [95% CI, 0.02-0.32]), and NfL from 1 to 12 weeks (1-week MD, 0.31 [95% CI, 0.12-0.51]; 2-week MD, 0.38 [95% CI, 0.19-0.58]; 4-week MD, 0.31 [95% CI, 0.12-0.51]; 6-week MD, 0.27 [95% CI, 0.07-0.47]; 8-week MD, 0.36 [95% CI, 0.15-0.56]; and 12-week MD, 0.25 [95% CI, 0.04-0.46]). Growth mixture modeling identified 2 GFAP subgroups: extreme prolonged (16%) and moderate transient (84%). For NfL, 3 subgroups were identified: extreme prolonged (7%), moderate prolonged (15%), and minimal or no change (78%). Individuals with SRC who reported loss of consciousness (LOC) (33% of SRC cases) had higher GFAP at 24 hours (MD, 1.01 [95% CI, 0.77-1.24]), 1 week (MD, 0.27 [95% CI, 0.06-0.49]), 2 weeks (MD, 0.21 [95% CI, 0.004-0.42]) and 4 weeks (MD, 0.34 [95% CI, 0.13-0.55]), and higher NfL from 1 week to 12 weeks (1-week MD, 0.73 [95% CI, 0.42-1.03]; 2-week MD, 0.91 [95% CI, 0.61-1.21]; 4-week MD, 0.90 [95% CI, 0.59-1.20]; 6-week MD, 0.81 [95% CI, 0.50-1.13]; 8-week MD, 0.73 [95% CI, 0.42-1.04]; and 12-week MD, 0.54 [95% CI, 0.22-0.85]) compared with SRC participants without LOC. Return to training times were longer in the GFAP extreme compared with moderate subgroup (incident rate ratio [IRR], 1.99 [95% CI, 1.69-2.34]; NfL extreme (IRR, 3.24 [95% CI, 2.63-3.97]) and moderate (IRR, 1.43 [95% CI, 1.18-1.72]) subgroups compared with the minimal subgroup, and for individuals with LOC compared with those without LOC (IRR, 1.65 [95% CI, 1.41-1.93]).

Conclusions and Relevance

In this cohort study, a subset of SRC cases, particularly those with LOC, showed heightened and prolonged increases in GFAP and NfL levels, that persisted for at least 4 weeks. These findings suggest that serial biomarker measurement could identify such cases, guiding return to play decisions based on neurobiologic recovery. While further investigation is warranted, the association between prolonged biomarker elevations and LOC may support the use of more conservative return to play timelines for athletes with this clinical feature.

Female RNA concussion (FeRNAC) study: assessing hormone profiles and salivary RNA in females with concussion by emergency departments in New Zealand: a study protocol

BACKGROUND

Females of reproductive age with concussion report a greater number of symptoms that can be more severe and continue for longer than age matched males. Underlying mechanisms for sex differences are not well understood. Short non-coding Ribonucleic Acids (sncRNAs) are candidate salivary biomarkers for concussion and have been studied primarily in male athletes. Female sex hormones influence expression of these biomarkers, and it remains unclear whether a similar pattern of sncRNA expression would be observed in females following concussion. This study aims to evaluate recovery time, the ratio of salivary sncRNAs and symptom severity across different hormone profiles in females presenting to emergency departments (ED) with concussion and, to investigate the presence of low energy availability (LEA) as a potential modifier of concussion symptoms.

METHODS

This prospective cohort study recruits participants from New Zealand EDs who are biologically female, of reproductive age (16-50 years) and with a confirmed diagnosis of concussion from an ED healthcare professional. Participants are excluded by ED healthcare professionals from study recruitment as part of initial routine assessment if they have a pre-diagnosed psychiatric condition, neurological condition (i.e., epilepsy, cerebral palsy) or more than three previously diagnosed concussions. Participants provide a saliva sample for measurement of sncRNA's, and online survey responses relating to hormone profile and symptom recovery at 7-day intervals after injury until they report a full return to work/study. The study is being performed in accordance with ethical standards of the Declaration of Helsinki with ethics approval obtained from the Health and Disability Ethics Committee (HDEC #2021 EXP 11655), Auckland University of Technology Ethics Committee (AUTEC #22/110) and locality consent through Wellington hospital research office.

DISCUSSION

If saliva samples confirm presence of sncRNAs in females with concussion, it will provide evidence of the potential of saliva sampling as an objective tool to aid in diagnosis of, and confirmation of recovery from, concussion. Findings will determine whether expression of sncRNAs is influenced by steroid hormones in females and may outline the need for sex specific application and interpretation of sncRNAs as a clinical and/or research tool.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) registration number ACTRN12623001129673.

Post-traumatic headache pathophysiology in paediatric concussion: A systematic review

Post-traumatic headache (PTH) represents the most common acute and persistent symptom following concussion in children, yet the underlying pathophysiology remains unclear. This systematic review sought to: (i) rigorously examine the current evidence of PTH pathophysiology in paediatric concussion (0-18 years), (ii) assess the quality of evidence, and (iii) provide directions for future research in accordance with PRISMA guidelines. Eligible studies (n = 19) totalling 1214 concussion participants investigated cerebrovascular function (n = 6), white matter integrity (n = 3), functional connectivity (n = 3), electrophysiology (n = 1), neurometabolics (n = 2), biological fluid markers (n = 4), vestibular and oculomotor function (n = 4); two studies used a multi-modal approach. Majority of studies were rated as fair quality (90%) and Level 3 evidence (84%). The true underlying mechanisms of PTH following paediatric concussion remain unclear. Overall quality of the available evidence is generally weak with a fair risk of bias and characterised by relative scarcity and lack of specificity of PTH pathophysiology. Future research is required to rigorously isolate pathophysiology specific to PTH with strict adherence to clinical definitions and standardised measurement tools of PTH.

Pediatric Sport-Related Concussion: Recommendations From the Amsterdam Consensus Statement 2023

The 6th International Consensus Conference on Concussion in Sport, Amsterdam 2022, addressed sport-related concussion (SRC) in adults, adolescents, and children. We highlight the updated evidence-base and recommendations regarding SRC in children (5-12 years) and adolescents (13-18 years). Prevention strategies demonstrate lower SRC rates with mouthguard use, policy disallowing bodychecking in ice hockey, and neuromuscular training in adolescent rugby. The Sport Concussion Assessment Tools (SCAT) demonstrate robustness with the parent and child symptom scales, with the best diagnostic discrimination within the first 72 hours postinjury. Subacute evaluation (>72 hours) requires a multimodal tool incorporating symptom scales, balance measures, cognitive, oculomotor and vestibular, mental health, and sleep assessment, to which end the Sport Concussion Office Assessment Tools (SCOAT6 [13+] and Child SCOAT6 [8-12]) were developed. Rather than strict rest, early return to light physical activity and reduced screen time facilitate recovery. Cervicovestibular rehabilitation is recommended for adolescents with dizziness, neck pain, and/or headaches for greater than 10 days. Active rehabilitation and collaborative care for adolescents with persisting symptoms for more than 30 days may decrease symptoms. No tests and measures other than standardized and validated symptom rating scales are valid for diagnosing persisting symptoms after concussion. Fluid and imaging biomarkers currently have limited clinical utility in diagnosing or assessing recovery from SRC. Improved paradigms for return to school were developed. The variable nature of disability and differences in evaluating para athletes and those of diverse ethnicity, sex, and gender are discussed, as are ethical considerations and future directions in pediatric SRC research.

Early intervention treatment in the first 2 weeks following concussion in adults: A systematic review of randomised controlled trials

OBJECTIVE

International guidelines support a repertoire of therapeutic interventions that may assist recovery following concussion. We aimed to systematically review the efficacy of early pharmacological and non-pharmacological interventions initiated within two weeks of injury on symptoms and functional recovery of adults with concussion.

METHODS

We conducted a Systematic Review (SR) of Randomised Controlled Trials (RCTs) without meta-analysis utilising the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search was performed of four databases. Study inclusion criteria were adult participants diagnosed with concussion and commencing active intervention within 14 days of injury.

RESULTS AND CONCLUSIONS

Of 7531 studies identified, 11 were included in the final review. Six studies were rated as high-risk of bias, three with some concerns and two as low-risk of bias. We found no evidence to support specific pharmacotherapeutic management to hasten the natural recovery time-course. Two studies reported significant improvement in selected concussion symptoms following manual therapy (at 48-72 hours post-treatment) or telephone counselling interventions (at 6 months post-injury). No high quality RCTs demonstrate superior effects of early therapeutic interventions on concussion recovery in the first 2 weeks. We advocate future research to examine impacts of health-clinician contact points aligned with symptom-specific interventions.

Use of Biostatistical Models to Manage Replicate Error in Concussion Biomarker Research

Importance

Advancing research on fluid biomarkers associated with sport-related concussion (SRC) highlights the importance of detecting low concentrations using ultrasensitive platforms. However, common statistical practices may overlook replicate errors and specimen exclusion, emphasizing the need to explore robust modeling approaches that consider all available replicate data for comprehensive understanding of sample variation and statistical inferences.

Objective

To evaluate the impact of replicate error and different biostatistical modeling approaches on SRC biomarker interpretation.

Design, Setting, and Participants

This cross-sectional study within the Surveillance in High Schools to Reduce the Risk of Concussions and Their Consequences study used data from healthy youth athletes (ages 11-18 years) collected from 3 sites across Canada between September 2019 and November 2021. Data were analyzed from November 2022 to February 2023.

Exposures

Demographic variables included age, sex, and self-reported history of previous concussion.

Main Outcomes and Measures

Outcomes of interest were preinjury plasma glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCH-L1), neurofilament-light (NFL), total tau (t-tau) and phosphorylated-tau-181 (p-tau-181) assayed in duplicate. Bland-Altman analysis determined the 95% limits of agreement (LOAs) for each biomarker. The impact of replicate error was explored using 3 biostatistical modeling approaches assessing the associations of age, sex, and previous concussion on biomarker concentrations: multilevel regression using all available replicate data, single-level regression using the means of replicate data, and single-level regression with replicate means, excluding specimens demonstrating more than 20% coefficient variation (CV).

Results

The sample included 149 healthy youth athletes (78 [52%] male; mean [SD] age, 15.74 [1.41] years; 51 participants [34%] reporting ≥1 previous concussions). Wide 95% LOAs were observed for GFAP (-17.74 to 18.20 pg/mL), UCH-L1 (-13.80 to 14.77 pg/mL), and t-tau (65.27% to 150.03%). GFAP and UCH-L1 were significantly associated with sex in multilevel regression (GFAP: effect size, 15.65%; β = -0.17; 95% CI, -0.30 to -0.04]; P = .02; UCH-L1: effect size, 17.24%; β = -0.19; 95% CI, -0.36 to -0.02]; P = .03) and single-level regression using the means of replicate data (GFAP: effect size, 15.56%; β = -0.17; 95% CI, -0.30 to -0.03]; P = .02; UCH-L1: effect size, 18.02%; β = -0.20; 95% CI, -0.37 to -0.03]; P = .02); however, there was no association for UCH-L1 after excluding specimens demonstrating more than 20% CV. Excluding specimens demonstrating more than 20% CV resulted in decreased differences associated with sex in GFAP (effect size, 12.29%; β = -0.14; 95% CI, -0.273 to -0.004]; P = .04) and increased sex differences in UCH-L1 (effect size, 23.59%; β = -0.27; 95% CI, -0.55 to 0.01]; P = .06), with the widest 95% CIs (ie, least precision) found in UCH-L1.

Conclusions and Relevance

In this cross-sectional study of healthy youth athletes, varying levels of agreement between SRC biomarker technical replicates suggested that means of measurements may not optimize precision for population values. Multilevel regression modeling demonstrated how incorporating all available biomarker data could capture replicate variation, avoiding challenges associated with means and percentage of CV exclusion thresholds to produce more representative estimates of association.

Improving outcome after paediatric concussion: challenges and possibilities

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

Headpulse Biometric Measures Following Concussion in Young Adult Athletes

Importance

Concussions are common in sports. Return-to-play protocols can be enhanced by objective biometrics.

Objective

To characterize temporal changes of headpulse, a digital biometric, in athletes with sports-related concussion; to explore the association of unstructured physical activity with headpulse changes.

Design, Setting, and Participants

This cohort study included headpulse measurements from players in the highest level of amateur Australian Rules Football in South Australia. Analysis included feasibility and validation phases, with the feasibility cohort recruited between August 5, 2021, and September 10, 2021, and the validation cohort recruited between May 5, 2022, and September 3, 2022. Data were analyzed October 2022 through January 2023.

Interventions

Cranial accelerometry detected micromovements of the head following cardiac contraction (what we have described as "headpulse"). Headpulse was serially recorded for 1 month in concussed individuals.

Main Outcomes and Measures

Headpulse waveforms underwent frequency transformation analysis per prespecified algorithm. Result Z scores were calculated. Headpulse Z scores exceeding 2 (2 SDs from control means) met an abnormality threshold. Headpulse sensitivity, timing, and duration of change were determined.

Results

A total of 59 control and 43 concussed individuals (44 total concussions; 1 control also concussed, 1 concussed individual injured twice) provided headpulse measurements. The feasibility cohort (all male) included 17 control (median [IQR] age, 23 [19-28] years) and 15 concussed individuals (median [IQR] age, 21 [19-23] years). The validation cohort included 25 female (median [IQR] age, 21 [20-22] years) and 17 male (median [IQR] age, 26 [23-29] years) control individuals, and 8 female (median [IQR] age, 28 [20-31] years) and 20 male (median [IQR] age, 21 [19-23] years) concussed individuals. Headpulse reached abnormality threshold in 26 of 32 concussed individuals (81%; 9% on day 0, 50% by day 2, 90% by day 14). Headpulse alterations lasted 14 days longer than symptoms and were exacerbated by return-to-play or unsupervised physical activity.

Conclusions and Relevance

In this study of 101 amateur Australian Rules Football athletes, the digital headpulse biometric was evaluated in 44 sports-related concussions. Compared with controls, new headpulse changes occurred after concussion; this objective metric may complement return-to-play protocols.