Head Impact Exposure Alters Neural Synchrony and Complexity in Collegiate Athletes

ObjectiveTo examine the effect of concussion history and cumulative exposure to collision sports on baseline serum biomarker concentrations, as well as associations between biomarker concentrations and clinical assessments.MethodsIn this observational cohort study, β-amyloid peptide 42 (Aβ42), total tau, S100 calcium binding protein B (S100B), ubiquitin carboxy-terminal hydrolyzing enzyme L1 (UCH-L1), glial fibrillary acidic protein, microtubule associated protein 2, and 2′,3′-cyclic-nucleotide 3′-phosphodiesterase serum concentrations were measured in 415 (61% male, 40% white, aged 19.0 ± 1.2 years) nonconcussed collegiate athletes without recent exposure to head impacts. Regression analyses were used to evaluate the relationship between self-reported history of concussion(s), cumulative years playing collision sports, clinical assessments, and baseline biomarker concentrations. Football-specific analyses were performed using a modified Cumulative Head Impact Index. Clinical assessments included symptom, cognitive, balance, and oculomotor tests.ResultsAthletes with a greater number of concussions had a higher baseline Aβ42 concentration only (ρ = 0.140, p = 0.005, small effect size). No biomarker concentrations correlated with cumulative exposure to collision sports. Race status fully mediated the correlations of S100B, UCH-L1, and Aβ42 with cognitive scores. Football exposure, specifically, was not associated with serum biomarker concentrations or clinical assessment scores based on the modified Cumulative Head Impact Index.ConclusionConcussion-related serum biomarkers showed no consistent association with concussion history, cumulative exposure to collision sports, or clinical assessments in a sample of healthy collegiate athletes. Serum Aβ42 concentrations could increase following multiple previous concussions. Considering race status is essential when investigating links between biomarkers and cognition. The biomarkers studied may not detect residual effects of concussion or repetitive head impact exposure in otherwise asymptomatic collegiate athletes without recent exposure to head impacts. Much more research is needed for identifying reliable and valid blood biomarkers of brain trauma history.

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The Effect of Repetitive Head Impact in Sensory Reweighting in Collision College Athletes

Neurology ◽

10.1212/01.wnl.0000581080.22077.74 ◽

2019 ◽

Vol 93 (14 Supplement 1) ◽

pp. S25.2-S26

Author(s):

Fernando Vanderlinde Santos ◽

Jaclyn Caccese ◽

Felipe Yamaguchi ◽

John Jeka

Keyword(s):

Repeated Measures ◽

Sport Participation ◽

Collegiate Athletes ◽

Vestibular Stimulation ◽

High Amplitude ◽

Head Impact ◽

Group Effect ◽

Contact Sport ◽

Sensory Reweighting ◽

Sinusoidal Waveform

ObjectiveTo compare sensory reweighting for upright stance between collegiate collision and non-contact sport athletes.BackgroundThe potentially adverse effects of repetitive head impact (RHI) exposure through routine collision sport participation have become a major public health concerns.Design/MethodsThirty male collegiate athletes were grouped by sport type, including collision (n = 15, 21.2 ± 2 years, 85.9 ± 13.8 kg, 179.7 ± 8.2 cm) and non-contact (n = 15, 20.8 ± 2.1 years, 72.9 ± 4.8 kg, 178.3 ± 4.3 cm) sport athletes. Participants underwent a standing balance assessment; they experienced simultaneous perturbations to visual, vestibular, and somatosensory systems. The visual stimulus consisted of 500 pyramids displayed on a virtual reality cave and translated in the anterior-posterior direction at 0.2 Hz in a sinusoidal waveform. The vestibular stimulus consisted of binaural-monopolar galvanic vestibular stimulation (GVS) at 0.36 Hz in a sinusoidal waveform. The somatosensory stimulus consisted of bilateral Achilles’ tendon vibration at 0.28 Hz in a square waveform with equal on/off times. Different frequencies were chosen for each modality so that we could calculate the gain to each stimulus independently. There were four conditions: two conditions of each high amplitude (0.2 m) and low amplitude (0.8 m) visual scene translation and two conditions of each vibration on and vibration off. The leg segment gain to each modality was compared between groups and across conditions using a repeated-measures ANOVA.ResultsThere were no changes in leg segment gain to vision (i.e. group effect; F = 2.624, p = 0.094, η2 = 0.086), gain to GVS (F = 1.341, p = 0.266, η2 = 0.46), or gain to vibration (F = 3.124, p = 0.088, η2 = 0.100). In addition, there were no changes in sensory reweighting for any modality (i.e. condition X group effect; vision, F = 0.074, p = 0.788, η2 = 0.003; GVS, F = 0.547, p = 0.46, η2 = 0.019; vibration, F = 0.734, p = 0.399, η2 = 0.026).ConclusionsOur findings suggest that there are no differences in sensory reweighting between collegiate collision and non-contact sport athletes. Despite concerns that RHI exposure through routine collision sport participation may result in balance disturbances, our results do not support this association.

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Spectrum of acute clinical characteristics of diagnosed concussions in college athletes wearing instrumented helmets

Journal of Neurosurgery ◽

10.3171/2012.8.jns112298 ◽

2012 ◽

Vol 117 (6) ◽

pp. 1092-1099 ◽

Cited By ~ 82

Author(s):

Ann-Christine Duhaime ◽

Jonathan G. Beckwith ◽

Arthur C. Maerlender ◽

Thomas W. McAllister ◽

Joseph J. Crisco ◽

...

Keyword(s):

Collegiate Athletes ◽

Head Impact ◽

Ice Hockey ◽

Future Research ◽

Impact Event ◽

Head Impacts ◽

Presenting Symptoms ◽

Wide Range ◽

Impact Events ◽

Specific Impact

Object Concussive head injuries have received much attention in the medical and public arenas, as concerns have been raised about the potential short- and long-term consequences of injuries sustained in sports and other activities. While many student athletes have required evaluation after concussion, the exact definition of concussion has varied among disciplines and over time. The authors used data gathered as part of a multiinstitutional longitudinal study of the biomechanics of head impacts in helmeted collegiate athletes to characterize what signs, symptoms, and clinical histories were used to designate players as having sustained concussions. Methods Players on 3 college football teams and 4 ice hockey teams (male and female) wore helmets instrumented with Head Impact Telemetry (HIT) technology during practices and games over 2–4 seasons of play. Preseason clinical screening batteries assessed baseline cognition and reported symptoms. If a concussion was diagnosed by the team medical staff, basic descriptive information was collected at presentation, and concussed players were reevaluated serially. The specific symptoms or findings associated with the diagnosis of acute concussion, relation to specific impact events, timing of symptom onset and diagnosis, and recorded biomechanical parameters were analyzed. Results Data were collected from 450 athletes with 486,594 recorded head impacts. Forty-eight separate concussions were diagnosed in 44 individual players. Mental clouding, headache, and dizziness were the most common presenting symptoms. Thirty-one diagnosed cases were associated with an identified impact event; in 17 cases no specific impact event was identified. Onset of symptoms was immediate in 24 players, delayed in 11, and unspecified in 13. In 8 cases the diagnosis was made immediately after a head impact, but in most cases the diagnosis was delayed (median 17 hours). One diagnosed concussion involved a 30-second loss of consciousness; all other players retained alertness. Most diagnoses were based on self-reported symptoms. The mean peak angular and rotational acceleration values for those cases associated with a specific identified impact were 86.1 ± 42.6g (range 16.5–177.9g) and 3620 ± 2166 rad/sec2 (range 183–7589 rad/sec2), respectively. Conclusions Approximately two-thirds of diagnosed concussions were associated with a specific contact event. Half of all players diagnosed with concussions had delayed or unclear timing of onset of symptoms. Most had no externally observed findings. Diagnosis was usually based on a range of self-reported symptoms after a variable delay. Accelerations clustered in the higher percentiles for all impact events, but encompassed a wide range. These data highlight the heterogeneity of criteria for concussion diagnosis, and in this sports context, its heavy reliance on self-reported symptoms. More specific and standardized definitions of clinical and objective correlates of a “concussion spectrum” may be needed in future research efforts, as well as in the clinical diagnostic arena.

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Practice type effects on head impact in collegiate football

Journal of Neurosurgery ◽

10.3171/2015.5.jns15573 ◽

2016 ◽

Vol 124 (2) ◽

pp. 501-510 ◽

Cited By ~ 33

Author(s):

Bryson B. Reynolds ◽

James Patrie ◽

Erich J. Henry ◽

Howard P. Goodkin ◽

Donna K. Broshek ◽

...

Keyword(s):

National Collegiate Athletic Association ◽

Collegiate Athletes ◽

Head Impact ◽

Football Players ◽

Rotational Acceleration ◽

Event Type ◽

Cumulative Impact ◽

Head Impacts ◽

Average Impact ◽

Collegiate Football

OBJECT This study directly compares the number and severity of subconcussive head impacts sustained during helmet-only practices, shell practices, full-pad practices, and competitive games in a National Collegiate Athletic Association (NCAA) Division I-A football team. The goal of the study was to determine whether subconcussive head impact in collegiate athletes varies with practice type, which is currently unregulated by the NCAA. METHODS Over an entire season, a cohort of 20 collegiate football players wore impact-sensing mastoid patches that measured the linear and rotational acceleration of all head impacts during a total of 890 athletic exposures. Data were analyzed to compare the number of head impacts, head impact burden, and average impact severity during helmet-only, shell, and full-pad practices, and games. RESULTS Helmet-only, shell, and full-pad practices and games all significantly differed from each other (p ≤ 0.05) in the mean number of impacts for each event, with the number of impacts being greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. The cumulative distributions for both linear and rotational acceleration differed between all event types (p < 0.01), with the acceleration distribution being similarly greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. For both linear and rotational acceleration, helmet-only practices had a lower average impact severity when compared with other event types (p < 0.001). However, the average impact severity did not differ between any comparisons of shell and full-pad practices, and games. CONCLUSIONS Helmet-only, shell, and full-pad practices, and games result in distinct head impact profiles per event, with each succeeding event type receiving more impacts than the one before. Both the number of head impacts and cumulative impact burden during practice are categorically less than in games. In practice events, the number and cumulative burden of head impacts per event increases with the amount of equipment worn. The average severity of individual impacts is relatively consistent across event types, with the exception of helmet-only practices. The number of hits experienced during each event type is the main driver of event type differences in impact burden per athletic exposure, rather than the average severity of impacts that occur during the event. These findings suggest that regulation of practice equipment could be a fair and effective way to substantially reduce subconcussive head impact in thousands of collegiate football players.

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