Relationship between concussion and neuropsychological performance in college football players

Ability of Head Impact Measurements to Predict Sports Concussions: A Review

BACKGROUND AND OBJECTIVES

Provide a review of the current landscape of motion sensor-based analyses of mild traumatic brain injury (concussion) and shed light on avenues for further investigation.

METHODS

A review of the literature on motion sensor-based concussion studies was conducted using search terms "concussion prediction sensor," "concussion prediction motion," "concussion diagnosis sensor," and "concussion diagnosis motion" in PubMed (between January 2000 and March 2024). In total, 207 publications were initially identified. However, only 14 studies were ultimately included, due to lack of requisite measurement variables, focus on different outcomes, or participant overlap with included studies. Consolidation of mean and standard deviation of measurement variables was performed using the application of Cochrane formula.

RESULTS

Across 14 studies, most used head impact data from football (85.7%) and the Head Impact Telemetry system for data acquisition (92.9%). Most of the studies used data sets from collegiate athletes (71.4%). A minority of studies included female athletes (14.3%). On average, male athletes experienced higher linear and rotational accelerations during concussive vs nonconcussive impacts (97.6 ± 33.8 g and 4614.9 ± 2568.7 rad/s2 vs 24.4 ± 16.2 g and 1641.9 ± 1216.6 rad/s2). Moreover, male athletes experienced higher linear accelerations, but similar rotational accelerations, compared with female athletes specifically during concussive impacts (97.6 ± 33.8 g and 4614.9 ± 2568.7 rad/s2 vs 43.0 ± 11.5 g and 4030 ± 1435 rad/s2). Notably, studies that predicted concussion probability using multivariate regression methods (26.7%) demonstrated challenges with accuracy due to low positive predictive values (ranging from 0.3%-0.9%) and high false-positive rates (up to 39.4%).

CONCLUSION

Despite the statistical differences in head impact measurements between concussive and nonconcussive impacts, they have limited clinical utility as a stand-alone concussion identification tool. Head impact measurements may be most useful when used as an adjunct to other clinical and physiological markers.

Assessing the capability of the corneal blink reflex to display neurological changes following subconcussive head impacts

Introduction

This study examines the capability of detecting neurological changes caused by subconcussive head impacts by analyzing the blink reflex of an individual when they encounter puffs of air as a stimulus.

Methods

Following attrition and technical issues, 26 participants (15 females, 11 males: age ± SD; 21.3 ± 2.11 years) with at least 5 years of soccer heading experience were included in the final analysis. Participants performed 10 soccer headers with soccer balls projected at a speed of 30 mph. Parameters related to blink reflex, including blink latency, differential latency, number of oscillations, delta 30, and excursions, were assessed by the EyeStat device at pre-heading baseline, and 2-h and 24-h post-heading.

Results

Significant declines in blink reflex parameters were observed at specific post-heading timepoints compared to baseline. At 24-h post-heading, significant reductions were detected in the overall blink latency (p = 0.0255), the blink latencies of the right eye (p = 0.0411), ipsilateral latency (p = 0.0314) and contralateral latency (p = 0.0434). At 2-h post-heading, significant declines were observed in the overall delta 30 value (p = 0.0053) and delta 30 of the right eye (p = 0.0260). Both delta 30 values returned to baseline by the 24-h post-heading timepoint. No significant changes in the differential latency, number of oscillations, and excursion of the eye were found.

Discussion

These findings suggest changes in the latency and delta 30 of a blink reflex is a viable measure of detection for neurological changes when monitoring subconcussive head impacts.

Concussion history and knowledge among top-level youth karate athletes

OBJECTIVE

To examine concussion experiences and knowledge among top-level youth karate athletes.

METHODS

This cross-sectional study collected data during the 12th World Karate Championships for cadets, juniors and under-21 athletes (held in Konya, Turkey, 2022). All 1414 registered athletes from 95 countries were invited to complete a 16-item paper-based questionnaire assessing demographic data, concussion history and concussion knowledge prior to the competing at the tournament. χ2 and Fisher's exact tests were used to analyse differences by sex, age group and continental karate federation.

RESULTS

A total of 654 athletes (46.3% response rate), including 286 (43.7%) females and 368 (56.3%) males, participated in the study, with 29.9% reporting one or more concussions during participation in karate training or competition. Older age groups (under 21 years) reported significantly higher concussion rates than younger athletes (56.9% vs 31.1% juniors and 24.7% cadets; p<0.001). Concussion knowledge revealed considerable gaps, with only 24.5% of athletes correctly identifying a concussion and 68.9% believing loss of consciousness was required for a concussion diagnosis. Misconceptions varied significantly across geographical regions, with Asian and African athletes demonstrating the greatest need for targeted education. Female athletes demonstrated better concussion reporting attitudes than males (60.4% vs 48.9%, p=0.004).

CONCLUSIONS

This study highlights the prevalence of concussions and significant knowledge gaps among top-level youth karate athletes, emphasising the need for tailored educational interventions to improve concussion recognition and management within the karate community.

The influence of sport-related concussion history on standing balance during upper limb movements under varying attentional demands

Sport-related concussions can influence athletic performance and everyday function. We implemented a dual-task paradigm whereby perturbed reaching while standing was combined with a simple reaction-time task. The purpose was to explore how concussion history influences balance control with and without external arm perturbations under varying attentional demands. Male athletes with no previous concussions (Hx0; n = 16; 19.3 ± 1.6 years) or history of two or more concussions (Hx2+; n = 16; 19.5 ± 1.8 years) participated. Participants reached to visual targets with their dominant hand and received randomly interspersed perturbations, performed either in isolation or simultaneously with a button press task with the non-dominant hand. Assessments included center of pressure (COP) parameters, hand movement reaction time and kinematics, and button-press reaction time. Participants with multiple concussions exhibited larger peak COP displacements and velocities than those with none. Compared to single task, the dual task increased cognitive processing and divided attention for both groups, demonstrated by slower button press and reaching reaction times, reduced anteroposterior hand velocity, and increased mediolateral hand displacement and velocity. Athletes with a concussion history likely have worse balance control, possibly owing to sensorimotor processing deficits or increased neural time delays leading to a subsequent reduction in motor activation. Because COP responses were overall maintained during the dual task, attentional resources were likely allocated towards maintaining balance control at the expense of upper limb performance.

Position-based assessment of head impact frequency, severity, type, and location in high school American football

Introduction

Research on head impact characteristics, especially position-specific investigations in football, has predominantly focused on collegiate and professional levels, leaving a gap in understanding the risks faced by high school players. Therefore, this study aimed to investigate the effect of three factors-player position, impact location, and impact type-on the frequency, severity, and characteristics of impacts in high school American football. Additionally, we examined whether and how player position influences the distribution of impact locations and types.

Methods

Sixteen high school football players aged 14 to 17 participated in this study. Validated mouthguard sensors measured head impact kinematics, including linear acceleration, angular acceleration, and angular velocity across ten games, and were used to identify impact locations on the head. Video recordings verified true impacts, player position, and impact type at the moment of each recorded impact. Head impact kinematics were input into a head finite element model to determine the 95th percentile of the maximum principal strain and strain rate. Several novel and systematic approaches, such as normalization, binning, and clustering, were introduced and utilized to investigate the frequency and severity of head impacts across the three aforementioned factors while addressing some of the limitations of previous methodologies in the field. To that end, the number of recorded impacts for each player position during each game was divided by the number of players in that position, and then averaged across ten games. Instead of averaging, impacts were categorized into four severity bins: low, mid-low, mid-high and high. Clusters for the three factors were also identified according to the characteristics of impacts.

Results and Discussion

Results revealed that offensive linemen and running backs experienced a higher normalized frequency and more severe impacts across all head kinematics and brain tissue deformation parameters. Frontal impacts, resulting from "head-to-head" impacts, were the most frequent and severe impact locations. The distributions of impact location and type for each specific position were distinct. Offensive linemen had the highest proportion of frontal impacts, while quarterbacks and centerbacks had more impacts at the rear location. These findings can inform interventions in game regulations, training practices, and helmet design to mitigate injury risks in high school football.

Influence of Preexisting Conditions and Concussion History on Postconcussion Symptom Severity and Recovery Time in Collegiate Athletes

Mental health conditions and concussion history reported by a collegiate athlete may contribute to prolonged recovery and symptom severity after concussion. This work examined the potential associations among concussion history, preexisting conditions, and sex relative to initial symptom severity and recovery duration following sport-related concussion (SRC) in a cohort of Division 1 National Collegiate Athletic Association athletes. This prospective cohort study analyzed symptom severity, recovery, and return-to-play (RTP) times reported post-SRC using data collected as part of the Pac-12 Concussion Assessment, Research and Education Affiliated Program and Health Analytics Program. Health history questionnaires that included self-reported history of preexisting conditions were completed at baseline. When consented athletes were diagnosed with a concussion, daily postconcussion symptom scores were evaluated until an athlete was clinically determined to be asymptomatic. Generalized linear and Cox proportional hazards models were used to determine associations between preexisting conditions and recovery and RTP times. Ninety-two concussions met inclusion criteria. Notable differences in initial symptom severity existed between females and males who had mood disorders (effect size [d] = 0.51) and attention-deficit hyperactivity disorder (ADHD; d = 0.93). The number of previous concussions was a strong predictor of athletes reporting preexisting mood disorders, depression, anxiety, and ADHD (p = 0.008-0.04). Females with ≥2 previous concussions required more days to RTP than males (d = 0.31-0.72). Weekly recovery and RTP probabilities substantially differed between athletes who did or did not have learning disorders (LDs; hazard ratio [HR]Recovery = 0.32, HRRTP = 0.22, d = 1.96-2.30) and ADHD (HRRecovery = 3.38, HRRTP = 2.74, d = 1.71-4.14). Although no association existed between concussion history and acute symptom severity, collegiate athletes with a history of concussion had higher probabilities of reporting depression, mood disorders, anxiety, and ADHD. Having ADHD or LDs likely strongly affects time to recovery and RTP for collegiate athletes.

Balance assessment under dual task conditions in patients with total knee arthroplasty: a test-retest reliability and concurrent validity study

BACKGROUND

Under dual-task (DT), functional mobility and balance testing can detect balance and mobility problems in activities of daily living, especially in situations that cannot be identified under single-task conditions.

OBJECTIVE

Determine the test-retest reliability and concurrent validity of the Four Square Step Test (FSST) under DT conditions for people with total knee arthroplasty (TKA).

METHOD

A total of 30 patients with TKA participated in this research, and patients were tested with the FSST under DT conditions. In addition, concurrent validity of the dual-task FSST was calculated using Timed Up and Go (TUG) under the single-task condition and Hospital for Special Surgery (HSS) Knee Score. Patients performed two FSST trials on the same day under DT conditions.

RESULTS

The intraclass correlation coefficients (ICC2,1) two-way random effects model, and minimal detectable changes with 95% confidence intervals (MDC95) values of the FSST under DT conditions were .97 and 3.43, respectively. The Pearson's correlation coefficient of the FSST with the TUG and HSS was .65 and -.40, respectively.

CONCLUSION

The FSST has been found to be a reliable and valid clinical assessment tool for dynamic balance under DT conditions in patients with TKA. For identify balance disorders in daily life at early points, clinicians and researchers can use the FSST under DT conditions in TKA.

CLINICAL TRIAL REGISTRATION NUMBER

NCT06108466.

Individual and Combined Effects of Sport-Related Concussion and Anterior Cruciate Ligament Injury on Neurocognitive and Neuromechanical Reaction Time

CONTEXT

Recent epidemiological data have indicated a potential connection between sport-related concussion (SRC) and elevated anterior cruciate ligament (ACL) injury risk. Limited research exists in which authors have quantified cognitive and motor outcome measures between SRC and ACL injury history.

OBJECTIVE

To examine the individual and combined effects of a history of SRC and ACL injury and reconstruction (ACLR) on neurocognitive and neuromechanical function.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty-seven recreationally active college individuals with either an injury history of SRC (n = 12), ACLR (n = 12), combination of SRC + ACLR (n = 11), or uninjured controls (n = 12).

MAIN OUTCOME MEASURE(S)

Participants completed a neurological battery using the C3 Logix application and TRAZER system for neuromechanical reaction time (RT). C3 Logix subtests consisted of the Trail Making Test (TMT) A, B, and B - A; simple and choice RT; and processing speed. TRAZER subtests consisted of simple, Flanker-task, and Stroop-task RT. Participants were categorized into 3 group comparisons of either (i) SRC, ACLR, SRC + ACLR, and controls, (ii) any or no SRC overall, or (iii) any or no ACLR overall.

RESULTS

No differences were demonstrated between SRC, ACLR, SRC + ACLR, and controls on TMT (P = .07-.14), neurocognitive (P = .14-.93), or neuromechanical (P = .64-.99) performance. Those with any SRC had slower TMT B - A times (P = .03), while those with any ACLR had slower TMT A (P = .02) times than those with no ACLR. No differences were noted for the TRAZER simple, Flanker, or Stroop RT for any or no SRC and ACLR groups.

CONCLUSIONS

College students with a combined effect of SRC and ACLR did not differ from other groups on neurocognition and neuromechanical RT. Individuals with a history of SRC or ACLR had a worse TMT, leading to inquiry about potential long-term neurological deficits, despite no differences in those with a combined history.

Perturbations in risk/reward decision making and frontal cortical catecholamine regulation induced by mild traumatic brain injury

Mild traumatic brain injury (mTBI) disrupts cognitive processes that influence risk taking behavior. Little is known regarding the effects of repetitive mild injury (rmTBI) or whether these outcomes are sex specific. Risk/reward decision making is mediated by the prefrontal cortex (PFC), which is densely innervated by catecholaminergic fibers. Aberrant PFC catecholamine activity has been documented following TBI and may underlie TBI-induced risky behavior. The present study characterized the effects of rmTBI on risk/reward decision making behavior and catecholamine transmitter regulatory proteins within the PFC. Rats were exposed to sham, single (smTBI), or three closed-head controlled cortical impact (CH-CCI) injuries and assessed for injury-induced effects on risk/reward decision making using a probabilistic discounting task (PDT). In the first week post-final surgery, mTBI increased risky choice preference. By the fourth week, males exhibited increased latencies to make risky choices following rmTBI, demonstrating a delayed effect on processing speed. When levels of tyrosine hydroxylase (TH) and the norepinephrine reuptake transporter (NET) were measured within subregions of the PFC, females exhibited dramatic increases of TH levels within the orbitofrontal cortex (OFC) following smTBI. However, both males and females demonstrated reduced levels of OFC NET following rmTBI. These results indicate the OFC is susceptible to catecholamine instability after rmTBI and suggests that not all areas of the PFC contribute equally to TBI-induced imbalances. Overall, the CH-CCI model of rmTBI has revealed time-dependent and sex-specific changes in risk/reward decision making and catecholamine regulation following repetitive mild head injuries.

Evaluating Recovery After Two and Three Repeated Concussions Using Growth Curves

The results of prior research concerning the effects of repeated concussions have been mixed. The aim of this study was to evaluate how concussion outcomes and presentation changed within patients who were evaluated at a concussion specialty clinic multiple times with a concussion. Subjects included 202 patients (54% male) aged 10-21 years (M = 13.17) who presented to a specialty concussion clinic for two and three concussions (77% sport-related) and were followed through formal clearance. First, growth curve models were estimated to determine recovery time and initial symptom burden across the multiple injuries. Second, covariates were added to these models to evaluate which demographic, risk factor, or injury variables predicted any change that did occur in evaluation or outcome variables. Models indicated that each subsequent concussion linearly resulted in significantly fewer days to recovery (-4.62 days, p < 0.047) across three concussions, and significantly lower (and linear) symptom scores on the post-concussion symptom scale (PCSS) (-2.16, p = 0.05). More severe presentation (i.e., days to recovery; higher symptom score) was significantly associated (-.62, p = 0.005) with greater improvement in recovery time (-.62, p = 0.005) and symptom burden (-.56, p < 0.001) at subsequent injuries. No covariates were significantly associated with improvement (or lack thereof) at subsequent injuries. This study adds to evidence suggesting multiple injuries is not associated with protracted recovery at subsequent injuries, in the context of treatment and full clearance for each injury at a multi-disciplinary clinic.

Relation Between Cognitive Assessment and Clinical Physical Performance Measures After Mild Traumatic Brain Injury

OBJECTIVES

To investigate the relation between cognitive and motor performance in individuals with mild traumatic brain injury (mTBI) and examine differences in both cognitive and motor performance between adults after mTBI and healthy controls.

DESIGN

Multi-center, cross-sectional study.

SETTING

Three institutional sites (Courage Kenny Research Center, Minneapolis, MN, Oregon Health & Science University, Portland, OR, and University of Utah, Salt Lake City, UT).

PARTICIPANTS

Data were collected from 110 participants (N=110), including those with mTBI and healthy controls, who completed cognitive and physical performance assessments.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Cognitive assessments involved the Automated Neuropsychological Assessment Metrics to evaluate domains of attention, memory, reaction time, processing speed, and executive function. Physical performance was evaluated through clinical performance assessments, such as the 1-min walk test, the modified Illinois Agility Test, the Functional Gait Assessment Tool, the High-Level Mobility Assessment Tool, a complex turning course, and a 4-Item Hybrid Assessment of Mobility for mTBI. Participants also completed additional trials of the 1-min walk test, modified Illinois Agility Test, and complex turning course with a simultaneous cognitive task.

RESULTS

Individuals with mTBI performed worse on cognitive assessments, as well as several of the physical performance assessments compared with healthy controls. Complex tasks were more strongly related to cognitive assessments compared with simple walking tasks.

CONCLUSIONS

Combining complex motor tasks with cognitive demands may better demonstrate functional performance in individuals recovering from mTBI. By understanding the relation between cognitive and physical performance in individuals recovering from mTBI, clinicians may be able to improve clinical care and assist in return to activity decision-making.

Henle fiber layer thickening and deficits in objective retinal function in participants with a history of multiple traumatic brain injuries

Introduction

This study tested whether multiple traumatic brain injuries (TBIs) alter the structure of the Henle fiber layer (HFL) and degrade cell-specific function in the retinas of human participants.

Methods

A cohort of case participants with multiple TBIs and a cohort of pair-matched control participants were prospectively recruited. Directional optical coherence tomography and scanning laser polarimetry measured HFL thickness and phase retardation, respectively. Full-field flash electroretinography (fERG) assessed retinal function under light-adapted (LA) 3.0, LA 30 Hz, dark-adapted (DA) 0.01, DA 3.0, and DA 10 conditions. Retinal imaging and fERG outcomes were averaged between both eyes, and paired t-tests or Wilcoxon signed-rank tests analyzed inter-cohort differences.

Results

Global HFL thickness was significantly (p = 0.02) greater in cases (8.4 ± 0.9 pixels) than in controls (7.7 ± 1.1 pixels). There was no statistically significant difference (p = 0.91) between the cohorts for global HFL phase retardation. For fERG, LA 3.0 a-wave amplitude was significantly reduced (p = 0.02) in cases (23.5 ± 4.2 μV) compared to controls (29.0 ± 8.0 μV). There were no other statistically significant fERG outcomes between the cohorts.

Discussion

In summary, the HFL thickens after multiple TBIs, but phase retardation remains unaltered in the macula. Multiple TBIs may also impair retinal function, indicated by a reduction in a-wave amplitude. These results support the potential of the retina as a site to detect TBI-associated pathology.

Psychometric Properties of Computerized Cognitive Tools and Standard Neuropsychological Tests Used to Assess Sport Concussion: A Systematic Review

Athletic programs are more frequently turning to computerized cognitive tools in order to increase efficiencies in concussion assessment. However, assessment using a traditional neuropsychological test battery may provide a more comprehensive and individualized evaluation. Our goal was to inform sport clinicians of the best practices for concussion assessment through a systematic literature review describing the psychometric properties of standard neuropsychological tests and computerized tools. We conducted our search in relevant databases including Ovid Medline, Web of Science, PsycINFO, and Scopus. Journal articles were included if they evaluated psychometric properties (e.g., reliability, sensitivity) of a cognitive assessment within pure athlete samples (up to 30 days post-injury). Searches yielded 4,758 unique results. Ultimately, 103 articles met inclusion criteria, all of which focused on adolescent or young adult participants. Test-retest reliability estimates ranged from .14 to .93 for computerized tools and .02 to .95 for standard neuropsychological tests, with strongest correlations on processing speed tasks for both modalities, although processing speed tasks were most susceptible to practice effects. Reliability was improved with a 2-factor model (processing speed and memory) and by aggregating multiple baseline exams, yet remained below acceptable limits for some studies. Sensitivity to decreased cognitive performance within 72 h of injury ranged from 45%-93% for computerized tools and 18%-80% for standard neuropsychological test batteries. The method for classifying cognitive decline (normative comparison, reliable change indices, regression-based methods) affected sensitivity estimates. Combining computerized tools and standard neuropsychological tests with the strongest psychometric performance provides the greatest value in clinical assessment. To this end, future studies should evaluate the efficacy of hybrid test batteries comprised of top-performing measures from both modalities.

The Effect of Ball Heading and Subclinical Concussion On the Neuromuscular Control Of The Lower Limb: A Systematic Review

Background

Soccer is unique among sports because it is the only sport that involves purposeful use of the head to control, pass, or shoot the ball. Over the previous five years, a relationship between lower extremity (LE) injury and sports related concussion (SRC) has been established in various sporting populations. Athletes at the high school, collegiate, and professional levels have demonstrated a greater risk for sustaining a LE injury post SRC. The purpose of this systematic review was to examine the relationship of the SRC with the incidence of LE injuries.

Methods

Ten databases were searched with the following keywords: Lower limb, ball heading, neuromuscular control, concussion, MEDLINE, Ovid MEDLINE(R) Daily, and Ovid MEDLINE(R), EMBASE, and Scopus. The search was limited to English-language and peer-reviewed publications, until 15/12/2022. The PEDro scale was used for the assessment of the risk of bias among the included studies. All included papers were qualitatively analyzed.

Results

A total of 834 studies were identified and 10 articles (four concussion-MSK biomechanics, six concussion-MSK injury) were included in the qualitative analyses. Included papers ranged from low to high quality. Due to the heterogeneous nature of the included study designs, quantitative meta-analysis was unable to be performed. All four of the included concussion-MSK biomechanics studies demonstrated, to some degree, that worse cognitive performance was associated with lower extremity MSK biomechanical patterns suggestive of greater risk for MSK injury. Among the six injury related studies, two investigations failed to determine group differences in cognitive performance between subsequently injured and non-injured athletes.

Conclusion

More research is needed to better understand the relationship of SRC and lower extremity injuries and the extent to which they are related to concussions and/or repetitive neurotrauma after ball heading sustained in soccer.

Level of Evidence

2.

Risk of impaired school performance in children hospitalized with concussion: a population-based matched cohort study

Aim

To examine the impact of concussion on objective measures of school performance.

Materials & methods

Population-based matched cohort study using linked health and education records of young people aged ≤18 years hospitalized with concussion in New South Wales, Australia, during 2005-2018, and matched comparisons not hospitalized with any injury.

Results

Young people with concussion had higher risk of not achieving the national minimum standards for literacy and numeracy assessments, ranging from 30% for numeracy to 43% for spelling, and not completing high school, ranging from 29% for year 10 to 77% for year 12, compared with matched peers.

Conclusion

Young people hospitalized with concussion have impaired school performance compared with uninjured matched peers.

Multispectral optoacoustic tomography (MSOT): Monitoring neurovascular changes in a mouse repetitive traumatic brain injury model

BACKGROUND

Evidence suggests that mild TBI injuries, which comprise > 75% of all TBIs, can cause chronic post-concussive symptoms, especially when experienced repetitively (rTBI). rTBI is a major cause of cognitive deficit in athletes and military personnel and is associated with neurovascular changes. Current methods to monitor neurovascular changes in detail are prohibitively expensive and invasive for patients with mild injuries.

NEW METHOD

We evaluated the potential of multispectral optoacoustic tomography (MSOT) to monitor neurovascular changes and assess therapeutic strategies in a mouse model of rTBI. Mice were subjected to rTBI or sham via controlled cortical impact and administered pioglitazone (PG) or vehicle. Oxygenated and deoxygenated hemoglobin were monitored using MSOT. Indocyanine green clearance was imaged via MSOT to evaluate blood-brain-barrier (BBB) integrity.

RESULTS

Mice subjected to rTBI show a transient increase in oxygenated/total hemoglobin ratio which can be mitigated by PG administration. rTBI mice also show BBB disruption shortly after injury and reduction of oxygenated/total hemoglobin in the chronic stage, neither of which were affected by PG intervention.

COMPARISON WITH EXISTING METHODS

MSOT imaging has the potential as a noninvasive in vivo imaging method to monitor neurovascular changes and assess therapeutics in mouse models of rTBI. In comparison to standard methods of tracking inflammation and BBB disruption, MSOT can be used multiple times throughout the course of injury without the need for surgery. Thus, MSOT is especially useful in research of rTBI models for screening therapeutics, and with further technological improvements may be extended for use in rTBI patients.

Microglial activation persists beyond clinical recovery following sport concussion in collegiate athletes

Introduction

In concussion, clinical and physiological recovery are increasingly recognized as diverging definitions. This study investigated whether central microglial activation persisted in participants with concussion after receiving an unrestricted return-to-play (uRTP) designation using [18F]DPA-714 PET, an in vivo marker of microglia activation.

Methods

Eight (5 M, 3 F) current athletes with concussion (Group 1) and 10 (5 M, 5 F) healthy collegiate students (Group 2) were enrolled. Group 1 completed a pre-injury (Visit1) screen, follow-up Visit2 within 24 h of a concussion diagnosis, and Visit3 at the time of uRTP. Healthy participants only completed assessments at Visit2 and Visit3. At Visit2, all participants completed a multidimensional battery of tests followed by a blood draw to determine genotype and study inclusion. At Visit3, participants completed a clinical battery of tests, brain MRI, and brain PET; no imaging tests were performed outside of Visit3.

Results

For Group 1, significant differences were observed between Visits 1 and 2 (p < 0.05) in ImPACT, SCAT5 and SOT performance, but not between Visit1 and Visit3 for standard clinical measures (all p > 0.05), reflecting clinical recovery. Despite achieving clinical recovery, PET imaging at Visit3 revealed consistently higher [18F]DPA-714 tracer distribution volume (VT) of Group 1 compared to Group 2 in 10 brain regions (p < 0.001) analyzed from 164 regions of the whole brain, most notably within the limbic system, dorsal striatum, and medial temporal lobe. No notable differences were observed between clinical measures and VT between Group 1 and Group 2 at Visit3.

Discussion

Our study is the first to demonstrate persisting microglial activation in active collegiate athletes who were diagnosed with a sport concussion and cleared for uRTP based on a clinical recovery.

Developing AI enabled sensors and decision support for military operators in the field

Wearable sensors enable down range data collection of physiological and cognitive performance of the warfighter. However, autonomous teams may find the sensor data impractical to interpret and hence influence real-time decisions without the support of subject matter experts. Decision support tools can reduce the burden of interpreting physiological data in the field and incorporate a systems perspective where noisy field data can contain useful additional signals. We present a methodology of how artificial intelligence can be used for modeling human performance with decision-making to achieve actionable decision support. We provide a framework for systems design and advancing from the laboratory to real world environments. The result is a validated measure of down-range human performance with a low burden of operation.

Lifetime Traumatic Brain Injury and Cognitive Domain Deficits in Late Life: The PROTECT-TBI Cohort Study

Traumatic brain injury (TBI) causes cognitive impairment but it remains contested regarding which cognitive domains are most affected. Further, moderate-severe TBI is known to be deleterious, but studies of mild TBI (mTBI) show a greater mix of negative and positive findings. This study examines the longer-term cognitive effects of TBI severity and number of mTBIs in later life. We examined a subset (n = 15,764) of the PROTECT study, a cohort assessing risk factors for cognitive decline (ages between 50 and 90 years). Participants completed cognitive assessments annually for 4 years. Cognitive tests were grouped using a principal components analysis (PCA) into working memory, episodic memory, attention, processing speed, and executive function. Lifetime TBI severity and number were retrospectively recalled by participants using the Brain Injury Screening Questionnaire (BISQ). Linear mixed models (LMMs) examined the effect of severity of head injury (non-TBI head strike, mTBI, and moderate-severe TBI) and number of mTBI at baseline and over time. mTBI was considered as a continuous and categorical variable (groups: 0 mTBI, 1 mTBI, 2 mTBIs, 3 mTBIs, and 4+ mTBIs). Of the participants 5725 (36.3%) reported at least one mTBI and 510 (3.2%) at least one moderate-severe TBI, whereas 3711 (23.5%) had suffered at worst a non-TBI head strike and 5818 (32.9%) reported no head injuries. The participants had suffered their last reported head injury an average (standard deviation, SD) of 29.6 (20.0) years prior to the study. Regarding outcomes, there was no worsening in longitudinal cognitive trajectories over the study duration but at baseline there were significant cognitive deficits associated with TBI. At baseline, compared with those without head injury, individuals reporting at least one moderate-severe TBI had significantly poorer attention (B = -0.163, p < 0.001), executive scores (B = -0.151, p = 0.004), and processing speed (B = -0.075, p = 0.033). Those who had suffered at least a single mTBI also demonstrated significantly poorer attention scores at baseline compared with the no head injury group (B = -0.052, p = 0.001). Compared with those with no mTBI, those in the 3 mTBI group manifested poorer baseline executive function (B = -0.149, p = 0.025) and attention scores (B = -0.085, p = 0.015). At baseline, those who had suffered four or more mTBIs demonstrated poorer attention (B = -0.135, p < 0.001), processing speed (B = -0.072, p = 0.009), and working memory (B = -0.052, p = 0.036), compared with those reporting no mTBI. TBI is associated with fixed, dose, and severity-dependent cognitive deficits. The most sensitive cognitive domains are attention and executive function, with approximately double the effect compared with processing speed and working memory. Post-TBI cognitive rehabilitation should be targeted appropriately to domain-specific effects. Significant long-term cognitive deficits were associated with three or more lifetime mTBIs, a critical consideration when counseling individuals post-TBI about continuing high-risk activities.

Initial Severity of Injury Has Little Effect on the Temporal Profile of Long-Term Deficits in Locomotion, Anxiety, and Cognitive Function After Diffuse Traumatic Brain Injury

Traumatic brain injury (TBI) is associated with persistent impairments in multiple domains, including cognitive and neuropsychiatric function. Previous literature has suggested that the risk of such impairments may differ as a function of the initial severity of injury, with moderate-severe TBI (msTBI) associated with more severe cognitive dysfunction and mild TBI (mTBI) associated with a higher risk of developing an anxiety disorder. Despite this, relatively few pre-clinical studies have investigated the time course of behavioral change after different severities of injury. The current study compared the temporal profile of functional deficits incorporating locomotion, cognition, and anxiety up to 12 months post-injury after an mTBI, repeated mild TBI (rmTBI), and single msTBI in an experimental model of diffuse TBI. Injury appeared to alter the effect of aging on locomotor activity, with both msTBI and rmTBI rats showing a decrease in locomotion at 12 months relative to their earlier performance on the task, an effect not observed in shams or after a single mTBI. Further, mTBI seemed to be associated with decreased anxiety over time, as measured by increased time spent in the open arm of the elevated plus maze from 3 to 12 months post-injury. No significant findings were observed on spatial memory or volumetric magnetic resonance imaging. Future studies will need to use a more comprehensive behavioral battery, capable of capturing subtle alterations in function, and longer time points, following rats into old age, in order to more fully assess the evolution of persistent behavioral deficits in key domains after different severities of TBI, as well as their accompanying neuroimaging changes. Given the prevalence and significance of such deficits post-TBI for a person's quality of life, as well as the elevated risk of neurodegenerative disease post-injury, such investigations may play a critical role in identifying optimal windows of therapeutic intervention post-injury.

The 50 Most Cited Papers Pertaining to American Football: Analysis of Studies From the Past 40 Years

Background

Bibliometric citation analyses have been widely used in medicine to help researchers gain foundational knowledge about a topic and identify subtopics of popular interest for further investigations.

Purpose

To identify the 50 most cited research publications related to American football.

Study Design

Cross-sectional study.

Methods

The Clarivate Analytics Web of Science database was used to generate a list of publications relating to football. Articles were filtered by the total number of citations, and the top 50 most cited articles studying the sport of football were selected for this analysis. Articles were analyzed by author, publication year, country of origin, institution affiliation, journal, article type, main research topic area, competitive level, and the level of evidence. A total of 247 articles were reviewed to reach the top 50 articles.

Results

The most studied topic within the top 50 articles was concussion/chronic traumatic encephalopathy (n = 40). Collegiate football was the most studied level of competition (n = 25). The journal publishing the greatest number of top articles was Neurosurgery. Two institutions, the University of North Carolina at Chapel Hill and Boston University School of Medicine, produced over one-third of top 50 articles (n = 18).

Conclusion

Our analysis indicated that most of the top 50 publications related to the sport of football focused on concussion and CTE, were observational, and were published during or after 2000. The most studied level of competition was collegiate football.

Academic skills, self-perceptions, and grades in university students with a history of multiple concussions: The mediating roles of processing speed and psychological symptoms

This study determined if university students with a history of multiple concussions may be at risk for academic difficulties and poor academic performance. We investigated if executive functioning, processing speed, and/or psychological symptoms might partially account for differences in academic performance of students with and without a history of multiple concussions.

University students with a history of three or more concussions (n = 58), one concussion (n = 57), or no concussion (n = 57) completed academic, cognitive, and psychological assessments.

Students with a history of multiple concussions read fewer words per minute and reported more learning difficulties than the no concussion group. Processing speed mediated the association between concussion status and reading rate. Psychological symptoms mediated the association between concussion status and self-reported learning difficulties.

University students with a history of multiple concussions may be at risk for poor academic outcomes due, at least in part, to slower processing speed and psychological symptoms.Treatment of psychological symptoms, cognitive rehabilitation to augment processing speed, and academic accommodations might improve academic outcomes for students with a history of three or more concussions.

Age of First Concussion and Cognitive, Psychological, and Physical Outcomes in NCAA Collegiate Student Athletes

OBJECTIVE

Concussions are common among youth athletes and could disrupt critical neurodevelopment. This study examined the association between age of first concussion (AFC) and neurocognitive performance, psychological distress, postural stability, and symptoms commonly associated with concussion in healthy collegiate men and women student athletes.

METHODS

Participants included 4267 collegiate athletes from various contact, limited-contact, and non-contact sports (1818 women and 2449 men) who completed baseline assessments as part of the Concussion Assessment, Research and Education (CARE) Consortium. Psychological distress was assessed with the Brief Symptom Inventory 18; neurocognitive performance was assessed with the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT); symptoms commonly associated with concussion were assessed with the ImPACT Post-Concussion Symptom Scale; postural stability was assessed with the Balance Error Scoring System. Generalized linear models were used to examine the effects of AFC on clinical outcomes separately in men and women.

RESULTS

Later AFC was associated with lower global (Exp(B) = 0.96, P = 0.001) and somatic (Exp(B) = 0.96, P = 0.002) psychological distress on the Brief Symptom Inventory 18 and faster ImPACT reaction time (B =  - 0.003, P = 0.001) in women. AFC was not associated with any clinical outcomes in men.

CONCLUSION

Younger AFC was associated with some differences in psychological distress and reaction time among women but not men; however, these results are likely not clinically meaningful. Sociodemographic disparities, pre-existing conditions, and sport type may impact clinical and cognitive outcomes in collegiate athletes more than concussion history. Future work should examine the relationship between AFC and lifespan-related outcomes.

Incipient chronic traumatic encephalopathy in active American football players: neuropsychological assessment and brain perfusion measures

Background and aims

Chronic traumatic encephalopathy (CTE) is a degenerative disease caused by repetitive traumatic brain injury (TBI). Because CTE can be definitely diagnosed only post-mortem, it would be important to explore clinical and radiological correlates of CTE and TBI. The aims of this study were to assess (1) the relationship between the neuropsychological profile of active American football players and the traumatic load; (2) whether traumatic brain injury associated with American football activity has a specific cerebral perfusion pattern; and (3) whether this perfusion pattern correlates with neuropsychological performances.

Methods

In 20 American football players [median age [25th–75th percentile] 25.0 [21.6–31.2] years, all males], we evaluated history, traumatic load and symptoms using the TraQ (Trauma Questionnaire), and cognitive performances on neuropsychological tests. Brain perfusion was estimated using arterial spin labeling MRI and compared to a group of 19 male age-matched (28.0 [24.8–32.3] years) healthy subjects.

Results

We found different cognitive performances between American football players stratified according to field position and career length. Linemen had poorer executive, verbal, and visual performances; a career > 7 years was associated with poorer verbal fluency performances. American football players had statistically significant reduced cerebral blood flow values in sensory-motor areas in comparison with healthy controls. Poorer neuropsychological performances correlated with lower perfusion in specific brain areas.

Conclusions

Our study seems to confirm that CTE in American football players is influenced by the field position and the career length, and correlates with lower cognitive performances linked to lower perfusion in specific brain areas.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-022-06212-7.

Short-Term Neurologic Manifestations of Repetitive Head Impacts Among Athletes: A Scoping Review

OBJECTIVE

To summarize the evidence linking contact sports-related repetitive head impacts (RHIs) and short-term declines in neurologic function.

METHODS

A scoping review following the guidelines in the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and searching 3 databases (PubMed, EMBASE, and Web of Science) was performed. Peer-reviewed research articles were eligible for inclusion if they were full-length English language articles published between 1999 and 2019 examining athletes between the ages of 14 and 40 years exposed to RHIs, and reporting cognitive, vestibular, and/or oculomotor outcomes within 4 weeks of last head hit exposure.

RESULTS

Fifty-two articles met criteria for review: 14 reported oculomotor outcomes, 23 reported vestibular outcomes, and 36 reported cognitive function. Short-term RHI-related declines in neurologic function were reported in 42.9% of oculomotor studies, in 20.8% of vestibular studies, and in 33.3% of cognitive studies. Most of the 52 studies involved American football, soccer, or ice hockey athletes at the collegiate ( n = 23) or high school ( n = 14) level. Twenty-four (46%) studies involved only male athletes. Wearable sensors were used to measure RHIs in 24 studies (46%), while RHIs were not measured in 26 studies (50%). In addition, many studies failed to control for attention-deficit/hyperactivity disorder/learning disability and/or concussion history.

CONCLUSION

The results of this scoping review suggest that the evidence linking RHIs to short-term declines in neurologic function is relatively sparse and lacking in methodological rigor. Although most studies failed to find a link, those that did were more likely to use objective measures of RHIs and to control for confounders. More careful trial design may be needed to definitively establish a causal link between RHIs and short-term neurologic dysfunction.

Structure and function of retinal ganglion cells in subjects with a history of repeated traumatic brain injury

This study tested whether repeated traumatic brain injuries (TBIs) alter the objective structure or the objective function of retinal ganglion cells (RGCs) in human subjects recruited from an optometry clinic. Case subjects (n = 25) with a history of repeated TBIs (4.12 ± 2.76 TBIs over 0-41 years) and healthy pair-matched control subjects (n = 30) were prospectively recruited. Retinal nerve fiber layer (RNFL) thickness was quantified with spectral-domain optical coherence tomography, and scanning laser polarimetry measured RNFL phase retardation. Measurements of the photopic negative response were made using full-field flash electroretinography. There was no statistically significant difference (p = 0.42) in global RNFL thickness between the case cohort (96.6 ± 9.4 microns) and the control cohort (94.9 ± 7.0 microns). There was no statistically significant difference (p = 0.80) in global RNFL phase retardation between the case cohort (57.9 ± 5.7 nm) and the control cohort (58.2 ± 4.6 nm). There were no statistically significant differences in the peak time (p = 0.95) of the PhNR or in the amplitude (p = 0.11) of the PhNR between the case cohort (69.9 ± 6.9 ms and 24.1 ± 5.1 μV, respectively) and the control cohort (70.1 ± 8.9 ms and 27.8 ± 9.1 μV, respectively). However, PhNR amplitude was more variable (p < 0.025) in the control cohort than in the case cohort. Within the case cohort, there was a strong positive (r = 0.53), but not statistically significant (p = 0.02), association between time since last TBI and PhNR amplitude. There was also a modest positive (r = 0.45), but not statistically significant (p = 0.04), association between time since first TBI and PhNR amplitude. Our results suggest that there were no statistically significant differences in the objective structure or in the objective function of RGCs between the case cohort and the control cohort. Future large, longitudinal studies will be necessary to confirm our negative results and to more fully investigate the potential interaction between PhNR amplitude and time since first or last TBI.

Allopurinol attenuates repeated traumatic brain injury in old rats: A preliminary report

Traumatic brain injury (TBI) is an overlooked cause of morbidity, which was shown to accelerate inflammation, oxidative stress, and neuronal cell loss and is associated with spatial learning and memory impairments and some psychiatric disturbances in older adults. However, there is no effective treatment in order to offer a favorable outcome encompassing a good recovery after TBI in older adults. Hence, the present study aimed to investigate the histological and neurobehavioral effects of Allopurinol (ALL) in older rats that received repeated TBI (rTBI). For this purpose, a weight-drop rTBI model was used on old male Wistar rats. Rats received 5 repeated TBI/sham injuries 24 h apart and were treated with saline or Allopurinol 100 mg/kg, i.p. each time. They were randomly assigned to three groups: control group (no injury); rTBI group (received 5 rTBI and treated with saline); rTBI+ALL group (received 5 rTBI and treated with Allopurinol). Then, half of the animals from each group were sacrificed on day 6 and the remaining animals were assessed with Open field, Elevated plus maze and Morris Water Maze test. Basic neurological tasks were evaluated with neurological assessment protocol every other day until after the 19th day from the last injury. Brain sections were processed for neuronal cell count in the hippocampus (CA1), dentate gyrus (DG), and prefrontal cortex (PC). Also, an immunohistochemical assay was performed to determine NeuN, iNOS, and TNFα levels in the brain regions. The number of neurons was markedly reduced in CA1, GD, and PC in rats receiving saline compared to those receiving allopurinol treatment. Immunohistochemical analysis showed marked induction of iNOS and TNFα expression in the brain tissues which were reduced after allopurinol at 6 and 19 days post-injury. Also, ALL-treated rats demonstrated a remarkable induce in NeuN expression, indicating a reduction in rTBI-induced neuronal cell death. In neurobehavioral analyses, time spent in closed arms, in the corner of the open field, swimming latency, and distance were impaired in injured rats; however, all of them were significantly improved by allopurinol therapy. To sum up, this study demonstrated that ALL may mitigate rTBI-induced damage in aged rats, which suggests ALL as a potential therapeutic strategy for the treatment of recurrent TBI.

The 100 Most-Cited and Influential Articles in Collegiate Athletics

Background

Bibliometric citation analyses have been widely used in medicine to help researchers gain foundational knowledge about a topic and identify subtopics of popular interest for further investigations. There is a lack of similar research in collegiate athletics.

Purpose

To identify the 100 most-cited research publications related to collegiate athletics.

Study Design

Cross-sectional study.

Methods

The Clarivate Analytics Web of Knowledge database was used to generate a list of articles relating to collegiate athletics on January 24, 2022. Articles were filtered by the total number of citations, and the 100 most-cited articles were selected. For each article, we identified and analyzed the following: author name, publication year, country of origin, journal name, article type, main research topic area, competitive level, sex of study population, and level of evidence.

Results

Of the top 100 most-cited articles, 63 were related to medicine. In total, 96% of articles were published in the United States, and 80% were published in the year 2000 or later. Of the top 100 articles, 85 were observational; only 5 were experimental. The sport most represented was soccer, followed by football, baseball, and basketball. Of the top 100 articles, 21 were published in a single journal, the American Journal of Sports Medicine. Ten authors published ≥5 of the top 100 most-cited studies.

Conclusion

The majority of top 100 articles were published in the United States after 1999 and primarily focused on medicine-related topics. Soccer was studied by more articles than football, baseball, and basketball. An author's prestige may have influenced the likelihood of citation. The top 100 most-cited studies provide researchers, medical students, residents, and fellows with a foundational list of the most important and influential academic contributions to the literature on collegiate athletics.

Recovery of symptoms, neurocognitive and vestibular-ocular-motor function and academic ability after sports-related concussion (SRC) in university-aged student-athletes: a systematic review

BACKGROUND

Physiological differences between a maturing and matured brain alters how Sports-Related Concussion (SRC) affects different age groups; therefore, a review specific to university-aged student-athletes is needed.

OBJECTIVES

Determine time to recovery for symptom burden, neurocognitive and Vestibular-Ocular-Motor (VOM) function and academic impact in university-aged student-athletes.

METHODS

Searches were conducted in PubMed, SpringerLink, PsycINFO, Science Direct, Scopus, Cochrane, Web of Science and EMBASE. Articles were included if they contained original data collected within 30 days in university-aged student-athletes, analysed SRC associated symptoms, neurocognitive or VOM function or academic ability and published in English. Two reviewers independently reviewed sources, using the Oxford Classification of Evidence-Based Medicine (CEBM) and the Downs and Black checklist, and independently extracting data before achieving consensus.

RESULTS

58 articles met the inclusion criteria. Recovery of symptoms occurred by 7 and 3-5.3 days for neurocognition. The evidence base did not allow for a conclusion on recovery time for VOM function or academic ability. Few papers investigated recovery times at specified re-assessment time-points and have used vastly differing methodologies.

CONCLUSIONS

To fully understand the implication of SRC on the university-aged student-athlete' studies using a multi-faceted approach at specific re-assessments time points are required.Systematic review registration number: CRD42019130685.

Preseason Symptom Reporting and Cognition in Middle School Athletes with Past Concussions

This study examined the association between past concussions and current preseason symptom reporting and cognitive performance in 9,257 youth ages 11-13. Participants completed neurocognitive testing prior to participating in a school sports between 2009 and 2019. We stratified the sample by gender and number of prior concussions and assessed group differences on the Post-Concussion Symptom Scale total score and the ImPACT cognitive composite scores. Those with≥2 prior concussions reported more symptoms than those with 0 concussions (d=0.43-0.46). Multiple regressions examining the contribution of concussion history and developmental/health history to symptom reporting showed the most significant predictors of symptoms scores were (in descending order): treatment for a psychiatric condition, treatment for headaches, history of learning disability (in boys only), history of attention-deficit/hyperactivity disorder, and age. Concussion history was the weakest statistically significant predictor in boys and not significant in girls. Cognitively, boys with 1 prior concussion had worse speed those with 0 concussions (d=0.11), and girls with≥2 prior concussions had worse verbal/visual memory than girls with 0 concussions (ds=0.38-0.39). In summary, youth with≥2 prior concussions reported more symptoms than those with no concussions. Boys with multiple concussions performed similarly on cognitive testing, while girls had worse memory scores.

What Is the Evidence on Natural Recovery Over the Year Following Sports-Related and Non-sports-Related Mild Traumatic Brain Injury: A Scoping Review

Background: Treatment approaches often differ dependent upon whether a person experiences a sports-related or a non-sports-related mild traumatic brain injury. It remains unclear if recovery from these injuries is comparable or unique to context of the injury. Objective: To identify knowledge gaps on self-reported outcomes and trajectories between sports- and non-sports-related mild traumatic brain injuries and how they are assessed in adults. Methods: This scoping review used a systematic search of key electronic databases, including PubMed, SPORTDiscus, Embase, MEDLINE, and CINAHL for articles published in 1937 until March 10, 2021. Articles were included if they were available in English; full text published in a peer-reviewed journal; had a prospective or retrospective study design; reported data on mild TBI cases >16 years of age, and included data from at least two time points on self-reported outcomes within 12 months post-injury. A standardized data extraction spreadsheet was used to determine the participant characteristics, definitions, assessment methods, outcomes, and recovery time frames. Results: Following removal of duplicates, the search strategy elicited 6,974 abstracts. Following abstract review, 174 were retained for full text review. Of the 42 articles that met inclusion criteria, 18 were sports related (15 in the USA and three in Canada) and 24 were general population studies (six in USA, three in Canada, three in Australasia, nine in Europe, two in Taiwan, and one in Morocco). Direct comparison in recovery trajectories between the sport and general population studies was difficult, given notable differences in methodology, definitions, types of outcome measures, and timing of follow-up assessments. Only one article reported on both sports-related and non-sports-related traumatic brain injuries separately at comparable timepoints. This study revealed no differences in recovery time frames or overall symptom burden. Discussion: Whilst there is a clear benefit in researching specific subpopulations in detail, standardized outcome measures and follow-up time frames are needed across contexts to facilitate understanding of similarities and differences between sports- and non-sports-related mild traumatic brain injuries to inform clinical treatment.

Top-100 Most-Cited Sports-Related Concussion Articles Focus on Symptomatology, Epidemiology, and Demographics

Purpose

To analyze the top-100 cited articles on sports-related concussions together with a bibliometric analysis to determine citations by year, level of evidence, study design, and several other factors related to the top referenced articles in sports concussions.

Methods

The Clarivate Analytics Web of Knowledge database was used to gather data using Boolean queries to capture all possible iterations of sports-related concussion research. Articles were organized in descending order based on the number of citations and included or excluded based on relevance to concussion. Collected information included author name, publication year, country of origin, journal name, article type, study focus, and the level of evidence.

Results

The top-100 articles were cited 31,197 times with an average of 312.0 citations per publication. More than one half were published in 2006 or later (52). Cohort studies and descriptive articles were the most prevalent study types (22 each). Studies with Level V evidence were the most common (33). The most common areas of study were symptomatology (short term, long term) with 17 articles, followed by epidemiology/demographics with 16 articles. The least common area of study was concussion prevention (2 articles), followed by management/treatment, diagnostics (labs, imaging) with 4 articles each.

Conclusions

We identified the most influential studies in sports-related concussion based on number of citations and citation density. A majority of these articles were published in the United States after 2006 and are most commonly cohort studies (Level IV evidence) and descriptive articles (Level V evidence). Current research focuses most heavily on the symptomatology and epidemiology/demographics of sports concussion.

Clinical Relevance

This study serves to identify the most influential articles in sports-related concussion and identify research topics with general deficiencies within the field of sports-related concussion research.

Prospective study with specific Re-Assessment time points to determine time to recovery following a Sports-Related Concussion in university-aged student-athletes

BACKGROUND

Time to recovery for symptom burden and neurocognition following a Sports-Related Concussion (SRC) has previously been determined by consolidating varying re-assessment time points into a singular point, and has not been established for Vestibular-Ocular-Motor (VOM) function or academic ability.

OBJECTIVES

Establish when recovery of symptom burden, neurocognition, VOM function, and academic ability occurs in university-aged student-athletes.

METHODS

Student-athletes completed an assessment battery (Post-Concussion Symptom Scale (PCSS), Immediate Post-Concussion Assessment and Cognitive Test (ImPACT), Vestibular Ocular-Motor Screening (VOMS), Perceived Academic Impairment Tool (PAIT)) during pre-season (n = 140), within 48 hours, 4, 8 and 14 days post-SRC and prior to Return To Play (RTP) and were managed according to the Rugby Football Union' community pathway (n = 42). Student-athletes were deemed recovered or impaired according to Reliable Change Index' (RCI) or compared to their individual baseline.

RESULTS

Symptom burden recovers by four days post-SRC on RCI and to baseline by eight days. VOM function and academic ability recovers by 8 days. Some student-athletes demonstrated worse performance at RTP on all tests by RCI and to baseline, except for on VOMS score and near point convergence by RCI change.

CONCLUSIONS

Variation in individual university-aged student-athletes requires a multi-faceted approach to establish what dysfunctions post-SRC exist and when recovery occurs.

Mild Cognitive Impairment and Dementia Reported by Former Professional Football Players over 50 Years of Age: An NFL-LONG Study

PURPOSE

To estimate prevalences of MCI and dementia diagnoses in former National Football League (NFL) players ≥50 years old and examine the relationships among these diagnoses and an array of predictors of long-term brain health.

METHODS

A cross-section of former NFL players (n = 922; aged [mean ± SD] 64.8 ± 8.9 years) completed a questionnaire. Prevalences of self-reported medical diagnoses of MCI and dementia were reported alongside U.S. population estimates across 5-year age intervals (e.g., 60-64 years). Prevalence ratios (PRs) were calculated for multiple predictors of long-term brain health.

RESULTS

Overall, MCI and dementia prevalences were n = 219(23.8%) and n = 82(8.9%), respectively. Each diagnosis was more prevalent in former NFL players across age groups than U.S. norms, with greater disparities at relatively younger ages (e.g., 65-69) compared with older ages. Greater prevalences of MCI and dementia were associated with: self-reported concussion history (10+ vs. 0; PRadjusted[95%CI] = 1.66[1.02-2.71] and 2.61[1.01-6.71], respectively); recent pain intensity (PRadjusted[95%CI] = 1.13[1.07-1.20] and 1.15[1.03-1.28]); and diagnoses of depression (PRadjusted[95%CI] = 2.70[1.92-3.81] and 3.22[1.69-6.14]), anxiety (PRadjusted[95%CI] = 1.96[1.26-3.07] and 3.14[1.47-6.74]), or both (PRadjusted[95%CI] = 3.11[2.38-4.08] and 4.43[2.71-7.25]). Higher MCI prevalence was related to sleep apnea (PRadjusted[95%CI] = 1.30[1.06-1.60]); higher dementia prevalence was associated with age (5-year interval, PRadjusted[95%CI] = 1.42[1.26-1.60]) and race (non-White vs. White, PRadjusted[95%CI] = 1.64[1.07-2.53]).

CONCLUSIONS

Self-reported MCI and dementia prevalences were higher in former NFL players than national estimates and were associated with numerous personal factors, including mood-related disorders and a high number of self-reported concussions. Predictors of higher MCI and dementia prevalence may be modifiable and warrant consideration by clinicians and researchers as potential targets to mitigate the onset of these conditions.

Altered Attention Network in Paratroopers Exposed to Repetitive Subconcussion: Evidence Based on Behavioral and Event-Related Potential Results

Cognitive impairment caused by repetitive subconcussion has received increasing attention in recent years. Although the dysfunction of attention has been confirmed by neuropsychological research using scales, there is no event-related potentials (ERPs) research. The Attention Network Test (ANT) has been widely used to evaluate the three separate components of attention processing (alerting, orienting, and executive control). Twenty-seven paratroopers exposed to repetitive subconcussion (subconcussion group) and 25 matched healthy control participants (HCs group) were enrolled, and all of them performed the ANT test while continuous scalp electroencephalography data were recorded. On the behavioral performance level, the subconcussion group showed a slower task response, with an especially significant slower reaction time in alerting. Concerning ERP results, reduction amplitudes of cue-N1 in the alerting network were observed, indicating that this group was less able to make efficient use of cues and maintain an alerting state for incoming information. For the orienting network, no difference in N1 amplitude was observed between the two groups. Moreover, there was a reduced P3 amplitude in the executive control network in the subconcussion group compared with the HCs group, suggesting a dysfunction of attentional resource allocation and inhibition control in the former group. This study is, to our knowledge, the first analysis of the altered attention network caused by repetitive subconcussion from the perspectives of behavioral and neuropsychology levels. These preliminary results revealed the possible damage of the alerting and executive control networks and provided a reference for further research on subconcussion cognitive impairment.

Paired cognitive flexibility task with symptom factors improves detection of sports-related concussion in high school and collegiate athletes

Determining the sensitivity and specificity of short neurocognitive assessments to objectively detect concussion will help clinicians more confidently integrate such tools in clinical management decisions. This study quantified the sensitivity and specificity of a computerized cognitive flexibility task isolating shifts of visuospatial attention in combination with clinical symptoms acutely (< 72 h) following concussion. A total of 100 athletes (53 concussed; 47 non-injured control; 42% female) completed computerized neurocognitive testing and clinical symptom reports (Sport Concussion Assessment Tool 3rd edition: SCAT3). Separate discriminant function analyses were performed for individual, combination, and stepwise inclusion of neurocognitive and clinical symptomology assessments. Findings revealed the combination of neurocognitive outcomes (i.e., mean reaction time, response accuracy, and response accuracy cost) with clinical symptom factor scores exhibited the greatest sensitivity (95.7%) and specificity (88.7%) as well as the highest positive predictive value (95.9%) and negative predictive value (88%) relative to other approaches. Further, a stepwise approach predicting concussion status using the discriminant functions improved detection of concussion (98.2% sensitivity, 95.7% specificity, 96.4% positive predictive value, and 97.8% negative predictive value) when clinical symptom factors failed to indicate the presence of a concussion. Incorporating a cognitive flexibility task involving shifts of visuospatial attention combined with clinical symptom factor scores may improve clinical decision-making as this approach exceeds the sensitivity and specificity of widely popular neurocognitive test batteries and takes less than 10 min to administer.

The role of salivary vesicles as a potential inflammatory biomarker to detect traumatic brain injury in mixed martial artists

Traumatic brain injury (TBI) is of significant concern in the realm of high impact contact sports, including mixed martial arts (MMA). Extracellular vesicles (EVs) travel between the brain and oral cavity and may be isolated from salivary samples as a noninvasive biomarker of TBI. Salivary EVs may highlight acute neurocognitive or neuropathological changes, which may be particularly useful as a biomarker in high impact sports. Pre and post-fight samples of saliva were isolated from 8 MMA fighters and 7 from controls. Real-time PCR of salivary EVs was done using the TaqMan Human Inflammatory array. Gene expression profiles were compared pre-fight to post-fight as well as pre-fight to controls. Largest signals were noted for fighters sustaining a loss by technical knockout (higher impact mechanism of injury) or a full match culminating in referee decision (longer length of fight), while smaller signals were noted for fighters winning by joint or choke submission (lower impact mechanism as well as less time). A correlation was observed between absolute gene information signals and fight related markers of head injury severity. Gene expression was also significantly different in MMA fighters pre-fight compared to controls. Our findings suggest that salivary EVs as a potential biomarker in the acute period following head injury to identify injury severity and can help elucidate pathophysiological processes involved in TBI.

Sport Contact Level Affects Post-Concussion Neurocognitive Performance in Young Athletes

OBJECTIVE

Contact level affects the incidence of sports-related concussion. However, the effects of contact level on injury severity and recovery are less clear and are the focus of this study.

METHOD

Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) for athletes aged 12-22 was performed at baseline (n = 10,907 for 7,058 athletes), after suspected concussion determined by physicians or athletic trainers (n = 5,062 for 4,419 athletes), and during follow-up visits (n = 3,264 for 2,098 athletes). Athletes played contact/collision (CC), limited contact (LC), and noncontact (NC) sports. Injury incidence, severity, and recovery were measured using raw and change from baseline neurocognitive test scores. Comparisons between groups used univariate analysis and multivariable regression controlling for demographic variables.

RESULTS

Compared to CC athletes, LC and NC athletes showed decreased suspected concussion incidence. At initial post-injury testing, all neurocognitive test scores were similar between groups except changes from baseline for processing speed were improved for LC compared to CC athletes. Upon follow-up testing, raw neurocognitive scores were better for NC compared to the contact collision athletes in verbal memory, processing speed, total symptom score, migraine cluster, cognitive cluster, and neuropsychiatric cluster scores. For change from baseline scores, LC athletes exhibited better performance on verbal memory, processing speed, and reaction time but also showed higher neuropsychiatric scores than CC athletes.

CONCLUSION

Neurocognitive scores between contact levels were similar at the first post-injury test. However, follow up showed many improved scores and symptoms for limited and NC sports compared to CC sports, which may indicate faster recovery.

Discrepancies in child and parent reporting of concussion symptoms

Objective: To assess discrepancies between child and parent symptom reports following concussion.Methods: Prospective cohort study involving 61 patients, age 7-21 years, diagnosed with a concussion within the previous 14 days. Children/parents completed the Child SCAT-3 symptom inventory at enrollment and 4 weeks post-injury. A within-subjects t-test was used to compare differences in child/parent response for each of 20 individual symptoms, 4 symptom domains, and total symptom severity. Pearson correlations were used to measure agreement between child/parent responses. A repeated measures analysis of variance assessed the effect of time on child/parent symptom discrepancy.Results: At enrollment, children reported higher symptom severity for 'distracted easily' (adj. p = .015) and 'confused' (adj. p = .015). There was moderate-to-high (r > 0.3) agreement between children and parents for more individual symptoms at enrollment (18/20) than at 4 weeks post-injury (14/20). Age had no effect (p > .05) on the discrepancy between child/parent reports.Conclusions: Although there was moderate-to-strong agreement between child/parent reports of concussion symptoms, discrepancies in individual cognitive symptom reports exist, in both children and adolescents. Therefore, collection of parent scales may provide useful information when tracking cognitive symptoms in adolescent patients, who may under-report or under-recognize cognitive deficits.

An Overview and Therapeutic Promise of Nutraceuticals against Sports-Related Brain Injury

Sports-related traumatic brain injury (TBI) is one of the common neurological maladies experienced by athletes. Earlier the term 'punch drunk syndrome' was used in the case TBI of boxers and now this term is replaced by chronic traumatic encephalopathy (CTE). Sports-related brain injury can either be short term or long term. A common instance of brain injury encompasses subdural hematoma, concussion, cognitive dysfunction, amnesia, headache, vision issue, axonopathy, or even death if remain undiagnosed or untreated. Further, chronic TBI may lead to pathogenesis of neuroinflammation and neurodegeneration via tauopathy, formation of neurofibrillary tangles, and damage to the blood-brain barrier, microglial, and astrocyte activation. Thus, altered pathological, neurochemical, and neurometabolic attributes lead to the modulation of multiple signaling pathways and cause neurological dysfunction. Available pharmaceutical interventions are based on one drug one target hypothesis and thereby unable to cover altered multiple signaling pathways. However, in recent time's pharmacological intervention of nutrients and nutraceuticals have been explored as they exert a multifactorial mode of action and maintain over homeostasis of the body. There are various reports available showing the positive therapeutic effect of nutraceuticals in sport-related brain injury. Therefore, in the current article we have discussed the pathology, neurological consequence, sequelae, and perpetuation of sports-related brain injury. Further, we have discussed various nutraceutical supplements as well as available animal models to explore the neuroprotective effect/ upshots of these nutraceuticals in sports-related brain injury.

Differences in cervical kinesthesia between amateur athletes with and without a history of contact sport participation

Objective: Identify cervical sensorimotor function differences between amateur athletes with and without a history of contact sport participation. A secondary aim of the study was to explore the association between neck reposition error and previously identified injury risk factors.Design: Cross-sectional.Participants: 27 amateur campus recreation sport athletes with a history of contact sport participation and 20 amateur campus recreation sport athletes with no history of contact sport.Main Outcome Measures: Baseline signs and symptoms (S/S) number and severity, Neck Disability Index, total neck reposition error, maximum reposition error, cervical range of motion, and cervical isometric strength were then compared between independent factor groups (contact vs. non-contact).Results: Amateur sport athletes with a history of contact sport exposure exhibited 25.2% more total neck reposition error and 24.6% more maximum neck reposition error than athletes with no history of contact sport participation. S/S number (r2 = .12, F(2,44) = 6.2, p = .017) and S/S severity (r2 = .14, F(2,44) = 5.6, p = .02) were significantly correlated with total neck reposition error.Conclusions: Athletes with a history of contact sport participation exhibited greater cervical spine reposition error. The degree to which these sensory position-sense deficits increase risk of injury and long-term quality of life is unknown, but should be explored in future studies.

Detection of mild traumatic brain injury in pediatric populations using BrainCheck, a tablet-based cognitive testing software: a preliminary study

Aim: Despite its high frequency of occurrence, mild traumatic brain injury (mTBI), or concussion, is difficult to recognize and diagnose, particularly in pediatric populations. Conventional methods to diagnose mTBI primarily rely on clinical questionnaires and sometimes include neuroimaging or pencil and paper neuropsychological testing. However, these methods are time consuming, require administration/interpretation from health professionals, and lack adequate test sensitivity and specificity. This study explores the use of BrainCheck Sport, a computerized neurocognitive test that is available on iPad, iPhone, or computer desktop, for mTBI assessment. The BrainCheck Sport Battery consists of 6 gamified traditional neurocognitive tests that assess areas of cognition vulnerable to mTBI such as attention, processing speed, executing functioning, and coordination. Methods: We administered BrainCheck Sport to 10 participants diagnosed with mTBI at the emergency department of Children’s hospital or local high school within 96 hours of injury, and 115 normal controls at a local high school. Statistical analysis included Mann-Whitney U test, chi-square tests, and Hochberg tests to examine differences between the mTBI group and control group on each assessment in the battery. Significant metrics from these assessments were used to build a logistic regression model that distinguishes mTBI from control participants. Results: BrainCheck Sport was able to detect significant differences in Coordination, Stroop, Immediate/Delayed Recognition between normal controls and mTBI patients. Receiver operating characteristic (ROC) analysis of our logistic regression model found a sensitivity of 84% and specificity of 81%, with an area under the curve of 0.884. Conclusions: BrainCheck Sport has potential in distinguishing mTBI from control participants, by providing a shorter, gamified test battery to assess cognitive function after brain injury, while also providing a method for tracking recovery with the opportunity to do so remotely from a patient’s home.

Effect of subconcussive impacts on functional outcomes over a single collegiate football season

Context

In collision sports, particularly American football, athletes can accumulate thousands of subconcussive impacts, or head acceleration events (HAEs), across a single season; however, the short-term consequences of these impacts are not well understood.

Objective

To investigate the effects of the accumulation of impacts during practices on cognitive functions over a single football season.

Design

Prospective observational study.

Setting

Athletic training room and University laboratory.

Participants

Twenty-three NCAA Football Bowl Subdivision players.

Main outcome measures

Helmet accelerometers during practices and virtual reality testing (VR; balance, reaction time, spatial memory) before and after the season.

Results

Preseason had the majority of ≥80 G impacts while during the season had the majority of ≥25 G to <80 G impacts and positional differences showed that linemen had the majority of both types. Virtual reality analysis revealed that scores significantly decreased after the season for spatial navigation ( p < 0.05) but not for balance or reaction time. Significant correlations ( p < 0.05) were found between cognitive measures and player demographic variables.

Conclusions

Even in the absence of clinical symptoms and concussion diagnosis, repetitive impacts may cause cognitive alterations. Documenting the distribution of impact quantity and intensity as a function of time and position may be considered by coaches and clinicians to reduce the accumulation of impacts in athletes exposed in contact sports.

Sensitivity and Specificity of Computer-Based Neurocognitive Tests in Sport-Related Concussion: Findings from the NCAA-DoD CARE Consortium

BACKGROUND

To optimally care for concussed individuals, a multi-dimensional approach is critical and a key component of this assessment in the athletic environment is computer-based neurocognitive testing. However, there continues to be concerns about the reliability and validity of these testing tools. The purpose of this study was to determine the sensitivity and specificity of three common computer-based neurocognitive tests (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT], CNS Vital Signs, and CogState Computerized Assessment Tool [CCAT]), to provide guidance on their clinical utility.

METHODS

This study analyzed assessments from a cohort of collegiate athletes and non-varsity cadets from the NCAA-DoD CARE Consortium. The data were collected from 2014-2018. Study participants were divided into two testing groups [concussed, n = 1414 (baseline/24-48 h) and healthy, n = 8305 (baseline/baseline)]. For each test type, change scores were calculated for the components of interest. Then, the Normative Change method, which used normative data published in a similar cohort, and the Reliable Change Index (RCI) method were used to determine if the change scores were significant.

RESULTS

Using the Normative Change method, ImPACT performed best with an 87.5%-confidence interval and 1 number of components failed (NCF; sensitivity = 0.583, specificity = 0.625, F1 = 0.308). CNS Vital Signs performed best with a 90%-confidence interval and 1 NCF (sensitivity = 0.587, specificity = 0.532, F1 = 0.314). CCAT performed best when using a 75%-confidence interval and 2 NCF (sensitivity = 0.513, specificity = 0.715, F1 = 0.290). When using the RCI method, ImPACT performed best with an 87.5%-confidence interval and 1 NCF (sensitivity = 0.626, specificity = 0.559, F1 = 0.297).

CONCLUSION

When considering all three computer-based neurocognitive tests, the overall low sensitivity and specificity results provide additional evidence for the use of a multi-dimensional assessment for concussion diagnosis, including symptom evaluation, postural control assessment, neuropsychological status, and other functional assessments.

Centre of pressure velocity shows impairments in NCAA Division I athletes six months post-concussion during standing balance

Sport-related concussion return to play (RTP) decisions are largely based on the resolution of self-reported symptoms and neurocognitive function. Some evaluators also incorporate balance; however, an objective approach to balance that can detect effects beyond the acute condition is warranted. The purpose of this study is to examine linear measures of biomechanical balance up to 6 months post-concussion, and to present preliminary diagnostic thresholds useful for RTP. Each concussed athlete participated in instrumented standing balance tasks at 4 timepoints post-concussion. The measures from concussed athletes were compared to the sport-matched non-concussed athlete group at each timepoint. Centre of pressure (COP) mediolateral (ML) velocity in double-leg stance on a hard surface discriminated well between non-concussed and concussed athletes. COP anterior-posterior (AP) velocity in tandem stance on foam showed sensitivity to concussion. Sixty per cent of athletes at 6 months post-concussion did not recover to within the proposed COP ML velocity threshold in double-leg stance on a hard surface. Seventy-one per cent of athletes at 6 months post-concussion did not recover to within the COP AP velocity threshold in tandem stance on foam. This lack of recovery potentially indicates vestibular and motor control impairments long past the typical period of RTP.

Neuropsychological Assessment of Sport-Related Concussion

Neuropsychological assessment is a key component in a comprehensive, multidisciplinary approach to assessment of sport-related concussion (SRC). Currently computerized tests are the most commonly used modality of neurocognitive testing and involve both baseline and postinjury assessments. A comprehensive neuropsychological assessment should not only include neurocognitive testing but also incorporate symptom inventories, vestibular-ocular screening, and a psychological evaluation. Neuropsychological assessments are most effective when completed by a Clinical Neuropsychologist, given their specialized training in test interpretation and conceptualization of the psychological, cognitive, behavioral, physiologic, as well as neurologic principals when treating and managing SRC.

Association of Cavum Septum Pellucidum and Cavum Vergae With Cognition, Mood, and Brain Volumes in Professional Fighters

Importance

Many studies have investigated the imaging findings showing sequelae of repetitive head trauma, with mixed results.

Objective

To determine whether fighters (boxers and mixed martial arts fighters) with cavum septum pellucidum (CSP) and cavum vergae (CV) have reduced volumes in various brain structures or worse clinical outcomes on cognitive and mood testing.

Design, Setting, and Participants

This cohort study assessed participants from the Professional Fighters Brain Health Study. Data were collected from April 14, 2011, to January 17, 2018, and were analyzed from September 1, 2018, to May 23, 2019. This study involved a referred sample of 476 active and retired professional fighters. Eligible participants were at least 18 years of age and had at least a fourth-grade reading level. Healthy age-matched controls with no history of trauma were also enrolled.

Exposures

Presence of CSP, CV, and their total (additive) length (CSPV length).

Main Outcomes and Measures

Information regarding depression, impulsivity, and sleepiness among study participants was obtained using the Patient Health Questionnaire depression scale, Barrett Impulsiveness Scale, and the Epworth Sleepiness Scale. Cognition was assessed using raw scores from CNS Vital Signs. Volumes of various brain structures were measured via magnetic resonance imaging.

Results

A total of 476 fighters (440 men, 36 women; mean [SD] age, 30.0 [8.2] years [range, 18-72 years]) and 63 control participants (57 men, 6 women; mean [SD] age, 30.8 [9.6] years [range, 18-58 years]) were enrolled in the study. Compared with fighters without CV, fighters with CV had significantly lower mean psychomotor speed (estimated difference, -11.3; 95% CI, -17.4 to -5.2; P = .004) and lower mean volumes in the supratentorium (estimated difference, -31 191 mm3; 95% CI, -61 903 to -479 mm3; P = .05) and other structures. Longer CSPV length was associated with lower processing speed (slope, -0.39; 95% CI, -0.49 to -0.28; P < .001), psychomotor speed (slope, -0.43; 95% CI, -0.53 to -0.32; P < .001), and lower brain volumes in the supratentorium (slope, -1072 mm3 for every 1-mm increase in CSPV length; 95% CI, -1655 to -489 mm3; P < .001) and other structures.

Conclusions and Relevance

This study suggests that the presence of CSP and CV is associated with lower regional brain volumes and cognitive performance in a cohort exposed to repetitive head trauma.

Neurophysiological markers of cognitive deficits and recovery in concussed adolescents

OBJECTIVE

The present study sought to determine: 1) whether concussed adolescents exhibited deficits in neurocognitive functioning as reflected by neurophysiological alterations; 2) if neurophysiological alterations could be linked to supplementary data such as the number of previous concussions and days since injury; and 3) if deficits in psychological health and behavioural tests increased during diagnosis duration.

METHODS

Twenty-six concussed adolescents were compared to twenty-eight healthy controls with no prior concussions. Self-report inventories evaluated depressive and concussive symptomatology, while behavioral tests evaluated cognitive ability qualitatively. To assess neurophysiological markers of cognitive function, two separate auditory oddball tasks were employed: 1) an active oddball task measuring executive control and attention as reflected by the N2b and P300, respectively; and 2) a passive oddball task assessing the early, automatic pre-conscious awareness processes as reflected by the MMN.

RESULTS

Concussed adolescents displayed delayed N2b and attenuated P300 responses relative to controls; showed elevated levels of depressive and concussive symptomatology; scored average-to- low-average in behavioral tests; and exhibited N2b response latencies that correlated with number of days since injury.

CONCLUSION

These findings demonstrate that concussed adolescents exhibit clear deficiencies in neurocognitive function, and that N2b response latency may be a marker of concussion recovery.

Saliva microRNA Biomarkers of Cumulative Concussion

Recurrent concussions increase risk for persistent post-concussion symptoms, and may lead to chronic neurocognitive deficits. Little is known about the molecular pathways that contribute to persistent concussion symptoms. We hypothesized that salivary measurement of microribonucleic acids (miRNAs), a class of epitranscriptional molecules implicated in concussion pathophysiology, would provide insights about the molecular cascade resulting from recurrent concussions. This hypothesis was tested in a case-control study involving 13 former professional football athletes with a history of recurrent concussion, and 18 age/sex-matched peers. Molecules of interest were further validated in a cross-sectional study of 310 younger individuals with a history of no concussion (n = 230), a single concussion (n = 56), or recurrent concussions (n = 24). There was no difference in neurocognitive performance between the former professional athletes and their peers, or among younger individuals with varying concussion exposures. However, younger individuals without prior concussion outperformed peers with prior concussion on three balance assessments. Twenty salivary miRNAs differed (adj. p < 0.05) between former professional athletes and their peers. Two of these (miR-28-3p and miR-339-3p) demonstrated relationships (p < 0.05) with the number of prior concussions reported by younger individuals. miR-28-3p and miR-339-5p may play a role in the pathophysiologic mechanism involved in cumulative concussion effects.

Neuropsychiatric Presentations due to Traumatic Brain Injury in Cognitively Normal Older Adults

Neuropsychiatric symptoms (NPS) are common sequelae of traumatic brain injuries (TBI) among adults. However, little is known about NPS associated with a history of TBI in adults relative to adults without a history of TBI and to what extent NPS may be modulated by sex and other factors. Using the National Alzheimer's Coordinating Center Uniform Data Set, we examined the association between Neuropsychiatric Inventory-Questionnaire (NPI-Q) scores in cognitively normal older adults with and without a history of TBI. A binomial logistic regression model was used to examine NPI-Q domains in adults with a history of TBI (n = 266) versus without a history of TBI (n = 1508). History of TBI, sex, age, and body mass index were used as covariates. Adults with a history of TBI had a greater probability of exhibiting agitation, anxiety, apathy, disinhibition and aberrant motor behavior relative to adults without a history of TBI. In terms of sex differences, males with and without a history of TBI had an increased likelihood of agitation, apathy, disinhibition, and apnea, whereas females had an increased likelihood of anxiety and insomnia relative to males. Our study confirms that history of TBI is associated with an increased prevalence of specific NPS, including agitation, anxiety, apathy, disinhibition, and aberrant motor behavior. Given that the aforementioned NPS are linked through different pathways, damage to any of them may cause an alteration in behavior. As well, NPS appear to be modulated by sex, with symptoms differing between males and females. Our research suggests future studies examining NPS sequelae of TBI should adjust for sex.