Athletes' age, sex, and years of education moderate the acute neuropsychological impact of sports-related concussion: a meta-analysis

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Recovery After Sport-Related Concussion in Collegiate Athletes With Self-Reported Pre-Injury Migraines

Pre-injury migraines might be a risk factor for prolonged recovery after sport-related concussion (SRC). We sought to examine whether a pre-injury history of migraines is associated with worse recovery following SRC in collegiate athletes. Data were collected through a prospective concussion surveillance system in 11 National Collegiate Athletic Association (NCAA) Division III college athletic programs between September 2014 and March 2020. Our primary independent variable, pre-injury migraines, were self-reported by the athletes. Between those with and without migraines, the outcomes of days to return-to-learn (RTL) without academic accommodations and return-to-play (RTP) were compared using Mann-Whitney U tests. Each athlete's RTL and RTP status was dichotomized (i.e., returned vs. not returned) at various time points for RTL (i.e., 7/14/21/28 days) and RTP (i.e., 14/21/28/56 days). Chi-squared tests were performed to compare the proportions of RTL and RTP status between groups. Multivariable regressions analyzed potential predictors of RTL and RTP adjusting for age, gender, prior concussions, other health conditions, and symptom severity. Of 1409 athletes with an SRC, 111 (7.9%) had a pre-injury history of migraines. Compared with those without migraines, those with migraines had longer median (interquartile range [IQR]) days to RTL (migraines = 7.0 [3.0-12.3] vs. no migraines = 5.0 [2.0-10.0], U = 53,590.5, p = 0.022). No differences were found in RTP between the two groups (migraines = 16.0 [10.0-33.0] vs. nχo migraines 15.0 [11.0-23.0], U = 38,545.0, p = 0.408). Regarding RTL, significantly lower proportions of athletes in the migraine group had fully RTL, without accommodations, at ≤14 days (77.5% vs. 85.2%, χ2 = 4.33, p = 0.037), ≤21 days (85.3% vs. 93.0%, χ2 = 7.99, p = 0.005), and ≤28 days (88.2% vs. 95.6%, χ2 = 10.60, p = 0.001). Regarding RTP, a significantly lower proportion of athletes in the migraine group RTP at ≤28 days (72.0% vs. 82.7%, χ2 = 5.40, p = 0.020) and ≤56 days (84.0% vs. 93.0%, χ2 = 8.19, p = 0.004). In a multivariable model predicting RTL that was adjusted for age, gender, acute concussion symptoms, and other health variables (e.g., attention-deficit/hyperactivity disorder [ADHD], history of mental health difficulties), pre-injury history of migraine was associated with longer RTL (β = 0.06, p = 0.030). In a multivariable model predicting RTP, pre-injury history of migraine was not associated with RTP (β = 0.04, p = 0.192). In collegiate athletes, pre-injury migraine history was independently associated with longer RTL but not RTP. When comparing the proportions of those with successful RTP by days, significantly lower proportions of those with migraines showed successful RTP at ≤28 days and ≤56 days. Futures studies should study the generalizability of our findings in other school levels.

Cognitive, Sleep-Arousal, Physical, and Affective Domain Scores on the Post-Concussion Symptom Scale: Added Utility in Detecting Symptom Elevations among Student-Athletes with a Remote History of Concussion

OBJECTIVE

The evaluation of self-reported symptoms is a standard component of concussion assessment and management. Clinicians typically evaluate a total symptom severity score rather than scores corresponding to specific symptom domains (i.e., cognitive, sleep-arousal, physical, and affective symptoms). This study examined (i) whether elevations in specific symptom domains would be missed when interpreting only the total symptom severity score and (ii) if a single symptom domain elevation was more common than having elevated symptoms across multiple domains.

METHOD

Adolescent student-athletes (N = 1,008) with concussion history (i.e., ≥6 months since last concussion) completed the Post-Concussion Symptom Scale (PCSS). The PCSS total score and cognitive, sleep-arousal, physical, and affective domain scores were calculated. To determine if symptoms were elevated, scores were compared to normative data matched on gender and pre-existing conditions, with scores considered elevated if they were ≥84th percentile. The frequency of total and domain score elevations were calculated and stratified by gender and number of prior concussions (i.e., 1 or ≥2 prior concussions).

RESULTS

Overall, 26% of student-athletes had an elevated symptom domain score without being elevated on the total score. The most common symptom presentation was to have a single elevated symptom domain (21%), followed by two (11%), three (8%), or four elevated domains (6%).

CONCLUSIONS

Interpreting PCSS symptom domains may be beneficial in detecting student-athletes with elevated symptoms following a remote concussion. Roughly a quarter of student-athletes have domain-specific symptom elevations that would be missed by interpreting the total score alone.

Systematic Review Examining the Reporting of Race and Ethnicity in Sport-Related Concussion Studies

OBJECTIVE

Sport-related concussion (SRC) is an evolving public health concern among youth athletes. Despite emerging evidence that race and ethnicity are important factors in determining concussion outcomes, studies examining race and ethnicity are limited. We conducted a systematic review to (1) determine the prevalence of SRC studies in which participants' race or ethnicity is reported, (2) describe how race and ethnicity are used within each study, and (3) assess predictive factors for the reporting of race and ethnicity.

DATA SOURCES

PubMed, Embase, PsycINFO, and CINAHL databases.

STUDY SELECTION

Study inclusion criteria were (1) primary and peer-reviewed research; (2) related to the diagnosis, treatment, or recovery of SRC; (3) involving school-aged athletes (ages 5 to 25); and (4) with 25 or more participants. The search was performed in March 2021 and included only studies published after March 2013.

DATA EXTRACTION

For each article, we looked at whether race and ethnicity were reported, and if so, which races or ethnicities were mentioned. For each race or ethnicity mentioned, we extracted the corresponding sample size and how they were used as variables in the study.

DATA SYNTHESIS

Of 4583 studies screened, 854 articles met inclusion criteria. Of the included articles, 132 (15.5%) reported race, and 65 (7.6%) reported ethnicity, whereas 721 (84.4%) reported neither. When examining the demographic characteristics of the 132 studies that reported race, 69.8% of athletes were White. Additionally, 79.5% of these studies used race solely as a demographic descriptor as opposed to a main exposure or covariate of interest. Studies published more recently were more likely to report race. Further, studies in specific study or journal topics and specific geographic locations of the authors were more likely to report race.

CONCLUSIONS

Reporting of race and ethnicity is limited in current SRC literature. Future authors should improve the reporting of race and ethnicity, diversify study samples by focusing on enrolling athletes from underrepresented groups, and consider the potential effect of race and ethnicity as social determinants of health on risk factors, recovery, and long-term sequelae after SRC.

Impact of Sex and Pubertal Development on Anxiety in Adolescents After Concussion

Concussion often results in psychological symptoms, including anxiety. Post-concussion anxiety has been well documented, although much of this research has focused on collegiate athletes. The purpose of this study was to compare (1) anxiety symptoms in concussed and healthy controls over time and (2) to explore sex differences in post-concussion anxiety within the context of pubertal development. Participants (N = 126, mean age = 15.1 years old), including concussed (n = 86) and healthy adolescents (n = 40), completed the Pubertal Development Scale (PDS) and the Screen for Child Anxiety and Related Disorders (SCARED-C). The concussed groups completed SCARED-C at three visits (<10 days, 4 weeks, 3 months). Results of an analysis of covariance (ANCOVA) and multi-variate analysis of covariance (MANCOVA) found concussed adolescents reported higher SCARED-C total, generalized, and panic anxiety scores than healthy controls, after controlling for sex, age, and PDS score (PDSS). A three-way mixed ANCOVA examined the effects of sex, PDSS, time, and their interaction on SCARED-C total score in concussed adolescents while controlling for age. There was a significant three-way interaction between sex, age, and PDSS on SCARED-C total score while controlling for age. Overall, we observed increased anxiety in concussed adolescents, compared with controls, as well as greater post-concussion anxiety reported by females compared with males, including within PDSS groups. Concussion providers should be prepared to receive training to administer well-validated measures of psychopathology and should consider that female adolescents, compared with males, regardless of pubertal development, may be at greater risk for post-concussion anxiety.

The influence of ADHD on recovery from sport concussion among collegiate athletes in the United States: LIMBIC MATARS consortium investigation

OBJECTIVE

The present study aimed to assess the potential influence of a diagnosis of ADHD on concussion recovery among collegiate athletes.

DESIGN

Retrospective and cross-sectional.

METHODS

Data were extracted retrospectively from medical records across LIMBIC MATARS member institutions (n = 11), representing 1,044 concussion cases among collegiate athletes. After exclusions, 406 concussions were included in our analysis (ADHD: n = 38, age = 20.2 ± 1.67 years, 18.4% female; No ADHD: n = 368, age = 19.8 ± 1.39 years, 40.1% female). Mann-Whitney U tests were used to compare days from injury to diagnosis, symptom resolution, and return to sport among athletes with and without ADHD.

RESULTS

No differences were observed for days from concussion until diagnosis (z = -0.33, p = 0.74), until days to symptom resolution (z = -1.30, p = 0.19), or days until return to sport (z = -0.68, p = 0.49); among concussion cases with or without a previously reported diagnosis of ADHD.

CONCLUSION

Our findings further expand the literature that suggests ADHD is not strongly associated with recovery trajectory following sport concussion in collegiate athletes. Future research should extend these findings to be inclusive of additional preexisting health conditions and moderating effects related to medication usage among diverse athlete levels.

Potential Biomarkers in Experimental Animal Models for Traumatic Brain Injury

Traumatic brain injury (TBI) is a complex and multifaceted disorder that has become a significant public health concern worldwide due to its contribution to mortality and morbidity. This condition encompasses a spectrum of injuries, including axonal damage, contusions, edema, and hemorrhage. Unfortunately, specific effective therapeutic interventions to improve patient outcomes following TBI are currently lacking. Various experimental animal models have been developed to mimic TBI and evaluate potential therapeutic agents to address this issue. These models are designed to recapitulate different biomarkers and mechanisms involved in TBI. However, due to the heterogeneous nature of clinical TBI, no single experimental animal model can effectively mimic all aspects of human TBI. Accurate emulation of clinical TBI mechanisms is also tricky due to ethical considerations. Therefore, the continued study of TBI mechanisms and biomarkers, of the duration and severity of brain injury, treatment strategies, and animal model optimization is necessary. This review focuses on the pathophysiology of TBI, available experimental TBI animal models, and the range of biomarkers and detection methods for TBI. Overall, this review highlights the need for further research to improve patient outcomes and reduce the global burden of TBI.

Close proximity to blast: No long-term or lasting effect on cognitive performance in service members with and without TBI during blast exposure

OBJECTIVE

Blast related characteristics may contribute to the diversity of findings on whether mild traumatic brain injury sustained during war zone deployment has lasting cognitive effects. This study aims to evaluate whether a history of blast exposure at close proximity, defined as exposure within 30 feet, has long-term or lasting influences on cognitive outcomes among current and former military personnel.

METHOD

One hundred participants were assigned to one of three groups based on a self-report history of blast exposure during combat deployments: 47 close blast, 14 non-close blast, and 39 comparison participants without blast exposure. Working memory, processing speed, verbal learning/memory, and cognitive flexibility were evaluated using standard neuropsychological tests. In addition, assessment of combat exposure and current post-concussive, posttraumatic stress, and depressive symptoms, and headache was performed via self-report measures. Variables that differed between groups were controlled as covariates.

RESULTS

No group differences survived Bonferroni correction for family-wise error rate; the close blast group did not differ from non-close blast and comparison groups on measures of working memory, processing speed, verbal learning/memory, or cognitive flexibility. Controlling for covariates did not alter these results.

CONCLUSION

No evidence emerged to suggest that a history of close blast exposure was associated with decreased cognitive performance when comparisons were made with the other groups. Limited characterization of blast contexts experienced, self-report of blast distance, and heterogeneity of injury severity within the groups are the main limitations of this study.

Sex comparisons in neuropsychological functioning and reported symptoms following a sports-related concussion among high school athletes

The aim of this study was to compare the neuropsychological functioning and symptoms of female and male high school athletes following a single concussion during the school year. The baseline test scores of the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) of 309 concussed athletes (169 females, 221 males) in varied sports were obtained. After a sport-related concussion, the athletes were re-administered the ImPACT, on the average, 7.25 days after the injury. MANCOVA compared the ImPACT baseline scores, post-concussion scores, and baseline-to-post-concussion changes of the female and male athletes, with p set at 0.01. The only significant sex comparison found females performing better on baseline visual motor speed (p < 0.001). Otherwise, no sex differences were found in baseline test scores, post-concussion scores, and baseline-to-post-concussion changes. The findings tentatively suggest that there are insignificant sex differences in the consequences of sport-related concussion after a week post-injury. Future studies on sex comparisons after a concussion are needed focusing on the acute and sub-acute phases of the recovery period.

Research Trends and Prospects of Sport-Related Concussion: A Bibliometric Study Between 2000 and 2021

BACKGROUND

Research around sport-related concussion (SRC) has made great advances during the twenty-first century. However, few studies have systematically analyzed the published SRC research.

METHODS

A bibliometric analysis was conducted of data from articles from the Web of Science Core Collection database. Descriptive statistics were used to analyze publication trends, most productive countries, institutions, authors, journals, research fields, and references with the highest citation number. VOSviewer software was used to perform network visualization and keywords co-occurrence analysis. CiteSpace software was used to perform reference co-citation analysis.

RESULTS

1) The number of publications and number of citations of research in SRC progressively increased between 2000 and 2021; 2) the United States was the leading country in research in SRC; 3) extensive cooperation among countries, institutions, and investigators was prevalent in SRC research; 4) P. McCrory, M. McCrea, and K.M. Guskiewicz were the 3 most prolific and influential authors; 5) research in SRC involved multidisciplinary perspectives and approaches; 6) research in SRC mainly covered aspects of primary prevention, diagnosis, and management, and the latter two have gained more attention in recent years; and 7) specific questions about "education," "predictors," "youth," "exercise," "reliability," "validity," and "baseline" were the research frontiers of SRC.

CONCLUSIONS

Attention to research in SRC has rapidly increased in recent years. Our work is a holistic overview that summarizes the hotspots, frontiers, and prospects of SRC, thus providing valuable information and guidance concerning research directions for those who are interested in or are dedicated to SRC research.

The School-Based Speech-Language Pathologist and Students With Concussion: An Examination of Evolving Knowledge and Confidence

PURPOSE

This study examines school-based speech-language pathologists' (SLPs') experience, knowledge, and confidence in supporting students as they return to the classroom following concussion, with a particular focus on knowledge of new management guidelines over the last decade.

METHOD

Participants were 74 school-based SLPs who completed an electronic survey about their knowledge and experiences serving students with concussion. We examined participants' accuracy and confidence across knowledge questions using Kruskal-Wallis tests. We also conducted linear regression to explore the relationships between training, work experiences, knowledge, and confidence.

RESULTS

Nearly half of participants who are currently working with students with concussion reported having no clinical or training experiences related to concussion. Participants who had more concussion-related training or working experiences reported higher confidence. Participants were confident about general concussion knowledge but less confident about providing assessment and supporting students with concussion as they returned to school. Participants had the lowest confidence and accuracy for the most recent guidelines around rest and activity, as well as the differential impact of concussion on children as compared to adults.

CONCLUSIONS

Many school-based SLPs have limited training around concussion management and are often not specifically consulted to work with students following concussion. Despite this, SLPs have good awareness of their knowledge about concussion, but show gaps in knowledge surrounding more recent evidence-based guidelines. Additional investigation is needed to determine better ways to move research into clinical practice and to increase the involvement of SLPs in school-based concussion teams.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20361969.

Sex Differences in Common Measures of Concussion in College Athletes

OBJECTIVE

Female athletes may be more likely to sustain a concussion and may vary in symptom presentation and neurocognitive impairments as compared with males. Scientific literature is limited by subjective assessments and underproportioned representation of women-the scope and etiology of sex-based differences are unknown. This study investigates sex-based differences in sports concussion assessments among college varsity athletes.

DESIGN AND SETTING

Retrospective study of an institution's athletic head injury database.

PARTICIPANTS

Acute postinjury and baseline data from 111 college athletes sustaining concussions between 2016 and 2018, diagnosed by a concussion specialist physician.

MAIN OUTCOME MEASURES

Concussion assessments examined included the Sports Concussion Assessment Tool (SCAT5) and Vestibular Oculomotor Screening (VOMS) performed within 3 days (24-72 hours) of injury.

RESULTS

No significant difference by sex was observed in the SCAT5 total symptom evaluation scores or severity scores, Standardized Assessment of Concussion, or Balance Error Scoring System ( P > .05) within 3 days of head injury. Females did report more "pressure in the head" severity scores from baseline to postconcussion (2.7 ± 1.5 increased symptomatology in females vs 1.8 ± 1.3 increase in males, P = .007). The VOMS test resulted in significant sex differences in smooth pursuit [0.6 ± 1.4 increase in females ( P < .001) vs 0.2 ± 0.6 increase in males ( P = .364)], horizontal saccades [0.6 ± 1.2 increase in females ( P < .001) vs 0.2 ± 0.5 increase in males ( P = .149)], and vertical saccades [0.9 ± 1.9 increase in females ( P < .001) vs 0.3 ± 0.7 increase in males ( P = .206)].

CONCLUSION

Our study did not show sex-based differences in baseline or acute postconcussive symptom reporting in most concussion assessment parameters, challenging previous research suggesting that females report more symptoms than males. Females did have significant differences in symptom provocation using the VOMS.

The Frequency of Low Scores on ImPACT in Adolescent Student-Athletes: Stratification by Race and Socioeconomic Status Using Multivariate Base Rates

This study examined the associations between the frequency of low scores on the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) by race and socioeconomic status (SES), using the proxy of Title I school status, among adolescent student-athletes and calculated multivariate base rates. There were 753 participants assigned to groups based on race (White: n = 430, 59.8%; Black: n = 289, 40.2%) and SES. Black student-athletes obtained more low neurocognitive test scores, which was associated with lower SES. The current study offers a resource to clinicians involved in concussion management who may wish to consider race and SES when interpreting ImPACT test performances.

Sex Differences in the Outcomes of Mild Traumatic Brain Injury in Children Presenting to the Emergency Department

Sex differences after concussion have been studied largely in high school and college athletes, often without reference to comparison groups without concussion. This study sought to evaluate sex differences in outcomes among all children and adolescents presenting to the Emergency Department (ED) for either mild traumatic brain injury (TBI) or orthopedic injury (OI), regardless of mechanism of injury. The study involved a concurrent cohort, prospective study design with longitudinal follow-up. Participants were eight to 16 years old with mild TBI (n = 143) or OI (n = 73). They were recruited and completed an initial assessment at EDs at two children's hospitals. They returned for a post-acute assessment within two weeks of injury and for follow-up assessments at three and six months. Outcomes included child and parent proxy ratings of somatic and cognitive symptoms, and standardized tests of cognitive functioning and balance. Sex did not moderate group differences in balance, fluid or crystallized cognitive ability, or child or parent proxy ratings of somatic or cognitive symptoms. Both parents and children reported more somatic symptoms in girls than boys, but in both groups. Compared with the OI group, the mild TBI group showed significantly lower fluid cognitive ability at the post-acute assessment and significantly higher somatic and cognitive symptoms according to both child and parent proxy ratings across the first two weeks post-injury. The results suggest that sex does not moderate the outcomes of mild TBI in a pediatric ED population. Previous research pointing to sex differences after concussion may reflect the lack of comparison groups, as well as a focus on adolescents and young adults and sport-related concussion. Future research should investigate whether sex moderates the outcomes of pediatric mild TBI in adolescents but not in pre-adolescent children.

Attention-Deficit/Hyperactivity Disorder Status and Sex Moderate Mild Traumatic Brain Injury Symptom Severity in Children and Adolescents: Implications for Clinical Management

OBJECTIVE

To investigate the impact of pediatric mild traumatic brain injury (mTBI), using a broad parent-reported measure, and to determine whether parent-ratings of mTBI symptoms are higher among those with premorbid attention-deficit/hyperactivity disorder (ADHD) and females.

DESIGN

Retrospective case-control.

SETTING

Hospital-based sports medicine clinic.

PARTICIPANTS

The retrospective chart review included 1346 (age: M = 13.11 years, SD = 2.6; 61.7% male) pediatric patients with (n = 209) and without (n = 1137) ADHD.

INDEPENDENT VARIABLES

Group membership (ADHD vs non-ADHD) and sex (male vs female).

MAIN OUTCOME MEASURES

Baseline and current Post-Concussion Symptom Inventory-Parent Report Form (PCSI-P) Physical, Emotional, Cognitive, and Fatigue subscale scores. This study used a retrospective chart review; therefore, the hypotheses reported for the current study were formed after data were collected.

RESULTS

Controlling for patient age and days from mTBI, patients with ADHD had significantly higher retrospective parent-reported pre-mTBI ratings of physical, emotional, and cognitive symptoms (ds = 0.17-0.62) and higher post-mTBI ratings across all 4 symptom domains (ds = 0.18-0.57) than those without ADHD. There was no group × time interaction for any of the PCSI-P subscales. Females overall had higher retrospective parent-reported pre-injury Fatigue and Emotional symptoms (ds = 0.13-0.19) and higher post-mTBI symptoms in all 4 PCSI-P symptom domains (ds = 0.23-0.35), relative to males.

CONCLUSIONS

Attention-deficit/hyperactivity disorder-related postinjury exacerbations in parent-reported symptoms can be explained, in part, by elevated retrospective parent-reported ADHD-related pre-mTBI ratings. These results highlight the importance of assessing a patient's baseline symptoms post-mTBI. These data also indicate that ADHD status and sex should be considered when interpreting mTBI symptom severity during clinical evaluation of concussion.

Using a Likelihood Heuristic to Summarize Conflicting Literature on Predictors of Clinical Outcome Following Sport-Related Concussion

OBJECTIVE

To introduce a new methodology for summarizing the results from systematic reviews-a likelihood heuristic-to the field of sport-related concussion.

DATA SOURCES

We applied the likelihood heuristic to the results of a systematic review published by Iverson et al (2017), containing 101 studies, on the predictors of worse clinical outcome following sport-related concussion.

STUDY SELECTION

We re-examined 5 individual prognostic factors that are of clinical interest and for which there is conflicting literature (female sex = 44 studies, prior concussion history = 41 studies, loss of consciousness = 31 studies, post-traumatic amnesia = 25 studies, and retrograde amnesia = 10 studies).

DATA EXTRACTION

For each prognostic factor, likelihood ratios were generated using the (1) number of significant and nonsignificant studies, (2) study power, (3) alpha level, and (4) prior probability that the alternative hypothesis was true.

DATA SYNTHESIS

Assuming each study had 80% power and an alpha level of 5%, observing the reported number of conflicting studies for female sex, prior concussion history, and retrograde amnesia is substantially more likely if each prognostic factor is associated with worse clinical outcome following sport-related concussion. For loss of consciousness, the observed number of conflicting studies is more likely if loss of consciousness is not associated with worse clinical outcome following sport-related concussion. A secondary analysis incorporating potentially more realistic study parameters of statistical power (45%) and alpha level (25%) generates weaker likelihood evidence that the observed numbers of studies for each prognostic factor are associated with worse clinical outcome following sport-related concussion than they are not.

CONCLUSIONS

Using a likelihood heuristic with 80% power and 5% alpha level, there is very strong likelihood evidence that female sex, prior concussion history, and retrograde amnesia are associated with worse clinical outcome following sport-related concussion. The strength of likelihood evidence that prognostic factors are associated with worse clinical outcome reduces when statistical power is lower and alpha level is inflated.

Preexisting conditions in older adults with mild traumatic brain injuries

OBJECTIVE

This study examined the prevalence of preexisting conditions that could affect premorbid brain health, cognition, and functional independence among older adults with mild traumatic brain injury (MTBI), and the relationship between preexisting conditions, injury characteristics, and emergency department (ED) discharge location (home versus continued care).

METHODS

Older adults (N = 1,427; 55-104 years-old; 47.4% men) who underwent head computed tomography (CT) after acute head trauma were recruited from the ED. Researchers documented preexisting medical conditions retrospectively from hospital records.

RESULTS

Multiple preexisting conditions increased in frequency with greater age, including circulatory and nervous system diseases and preexisting abnormalities on head CT. Psychiatric and substance use disorders (SUDs) decreased in frequency with greater age. Among participants with uncomplicated MTBI and GCS = 15, preexisting nervous system diseases and preexisting CT abnormalities were associated with higher odds of continued care for all participants, whereas psychiatric disorders and SUDs were only associated with higher odds of continued care among participants <70 years-old. Preexisting circulatory diseases, loss of consciousness, and amnesia were unassociated with discharge location.

CONCLUSIONS

Preexisting medical conditions that could affect brain and cognitive health occur commonly among older adults who sustain MTBIs. These conditions can confound research examining post-injury outcomes within this age group.

Omega-3 Fatty Acids and Vitamin D Decrease Plasma T-Tau, GFAP, and UCH-L1 in Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) results in neuronal, axonal and glial damage. Interventions targeting neuroinflammation to enhance recovery from TBI are needed. Exercise is known to improve cognitive function in TBI patients. Omega-3 fatty acids and vitamin D reportedly reduce inflammation, and in combination, might improve TBI outcomes. This study examined how an anti-inflammatory diet affected plasma TBI biomarkers, voluntary exercise and behaviors following exposure to mild TBI (mTBI). Adult, male rats were individually housed in cages fitted with running wheels and daily running distance was recorded throughout the study. A modified weight drop method induced mTBI, and during 30 days post-injury, rats were fed diets supplemented with omega-3 fatty acids and vitamin D₃ (AIDM diet), or non-supplemented AIN-76A diets (CON diet). Behavioral tests were periodically conducted to assess functional deficits. Plasma levels of Total tau (T-tau), glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase L1 (UCH-L1) and neurofilament light chain (NF-L) were measured at 48 h, 14 days, and 30 days post-injury. Fatty acid composition of food, plasma, and brain tissues was determined. In rats exposed to mTBI, NF-L levels were significantly elevated at 48 h post-injury (P < 0.005), and decreased to levels seen in uninjured rats by 14 days post-injury. T-tau, GFAP, and UCH-L1 plasma levels did not change at 48 h or 14 days post-injury. However, at 30 days post-injury, T-tau, GFAP and UCH-L1 all significantly increased in rats exposed to mTBI and fed CON diets (P < 0.005), but not in rats fed AIDM diets. Behavioral tests conducted post-injury showed that exercise counteracted cognitive deficits associated with mTBI. The AIDM diets significantly increased docosahexaenoic acid levels in plasma and brain tissue (P < 0.05), and in serum levels of vitamin D (P < 0.05). The temporal response of the four injury biomarkers examined is consistent with studies by others demonstrating acute and chronic neural tissue damage following exposure to TBI. The anti-inflammatory diet significantly altered the temporal profiles of plasma T-tau, GFAP, and UCH-L1 following mTBI. Voluntary exercise protected against mTBI-induced cognitive deficits, but had no impact on plasma levels of neurotrauma biomarkers. Thus, the prophylactic effect of exercise, when combined with an anti-inflammatory diet, may facilitate recovery in patients with mTBI.

Identifying degenerative effects of repetitive head trauma with neuroimaging: a clinically-oriented review

BACKGROUND AND SCOPE OF REVIEW

Varying severities and frequencies of head trauma may result in dynamic acute and chronic pathophysiologic responses in the brain. Heightened attention to long-term effects of head trauma, particularly repetitive head trauma, has sparked recent efforts to identify neuroimaging biomarkers of underlying disease processes. Imaging modalities like structural magnetic resonance imaging (MRI) and positron emission tomography (PET) are the most clinically applicable given their use in neurodegenerative disease diagnosis and differentiation. In recent years, researchers have targeted repetitive head trauma cohorts in hopes of identifying in vivo biomarkers for underlying biologic changes that might ultimately improve diagnosis of chronic traumatic encephalopathy (CTE) in living persons. These populations most often include collision sport athletes (e.g., American football, boxing) and military veterans with repetitive low-level blast exposure. We provide a clinically-oriented review of neuroimaging data from repetitive head trauma cohorts based on structural MRI, FDG-PET, Aβ-PET, and tau-PET. We supplement the review with two patient reports of neuropathology-confirmed, clinically impaired adults with prior repetitive head trauma who underwent structural MRI, FDG-PET, Aβ-PET, and tau-PET in addition to comprehensive clinical examinations before death.

REVIEW CONCLUSIONS

Group-level comparisons to controls without known head trauma have revealed inconsistent regional volume differences, with possible propensity for medial temporal, limbic, and subcortical (thalamus, corpus callosum) structures. Greater frequency and severity (i.e., length) of cavum septum pellucidum (CSP) is observed in repetitive head trauma cohorts compared to unexposed controls. It remains unclear whether CSP predicts a particular neurodegenerative process, but CSP presence should increase suspicion that clinical impairment is at least partly attributable to the individual's head trauma exposure (regardless of underlying disease). PET imaging similarly has not revealed a prototypical metabolic or molecular pattern associated with repetitive head trauma or predictive of CTE based on the most widely studied radiotracers. Given the range of clinical syndromes and neurodegenerative pathologies observed in a subset of adults with prior repetitive head trauma, structural MRI and PET imaging may still be useful for differential diagnosis (e.g., assessing suspected Alzheimer's disease).

Physical Conditioning Strategies for the Prevention of Concussion in Sport: a Scoping Review

BACKGROUND

Concussion in sports has received a great deal of media attention and may result in short and longer-lasting symptoms, especially in adolescents. Although significant strides have been made in the identification and management of concussion, less is known about the primary prevention of this condition. The aims of this scoping review are to (1) summarize the current research of physical conditioning strategies to reduce or prevent concussion incidence in individuals participating in sport, especially adolescents, and (2) to identify gaps in the knowledge base. Our research question was what is known from the existing literature about physical preparation strategies to reduce or prevent concussion in adult and adolescent sports?

METHODS

Three literature searches were conducted by information officers at two universities at six-month intervals, using five electronic databases (PubMed; WorldCat.org ; Mendeley; EBSCOHost and Ovid MEDLINE). To increase the search range, subject experts were consulted and articles and reference lists were hand searched. A scoping review methodology identified eligible studies that analyzed physical preparation techniques on modifiable physical risk factors in athletes to reduce the incidence of concussion. The PRISMA-ScR checklist guided the reporting of the findings.

RESULTS

A total of 1414 possible articles were identified, after duplicates removed, and articles analyzed against the inclusion and exclusion criteria, only 9 articles qualified for analysis. Two articles were found from studying reference lists. Thus, a total of 11 articles were included in the final evaluation for the purposes of this study. Data are reported from mostly adolescent subjects participating in nine different sports from three countries. Findings are presented with specific reference to previously recognized modifiable risk factors of concussion which include neck strength, neck size, cervical stiffness, type of sport, and pre-activity exercises.

CONCLUSIONS

There is limited research examining the physical preparation of athletes, especially in adolescents, to reduce or prevent concussion, and conflicting evidence in the few small sample studies that were identified. This scoping review identifies the research gap for a potentially vital modifiable risk factor, notably in the physical preparation of children and adolescents to reduce or prevent sports-related concussion.

Making a Difference: Affective Distress Explains Discrepancy Between Objective and Subjective Cognitive Functioning After Mild Traumatic Brain Injury

OBJECTIVE

To assess the relationship between subjective cognitive symptoms and objective cognitive test scores in patients after concussion. We additionally examined factors associated with subjective and objective cognitive dysfunction, as well as their discrepancy.

PARTICIPANTS

Eighty-six individuals (65.1% female; 74.4% adult) from an interdisciplinary concussion clinic.

METHODS

Subjective and objective cognitive functioning was measured via the SCAT-Symptom Evaluation and the CNS Vital Signs Neurocognition Index (NCI), respectively. Cognitive discrepancy scores were derived by calculating standardized residuals (via linear regression) using subjective symptoms as the outcome and NCI score as the predictor. Hierarchical regression assessed predictors (age, education, time postinjury, attention-deficit/hyperactivity disorder, affective distress, and sleep disturbance) of cognitive discrepancy scores. Nonparametric analyses evaluated relationships between predictor variables, subjective symptoms, and NCI.

RESULTS

More severe affective and sleep symptoms (large and medium effects), less time postinjury (small effect), and older age (small effect) were associated with higher subjective cognitive symptoms. Higher levels of affective distress and less time since injury were associated with higher cognitive discrepancy scores (β = .723, P < .001; β = -.204, P < .05, respectively).

CONCLUSION

Clinical interpretation of subjective cognitive dysfunction should consider these additional variables. Evaluation of affective distress is warranted in the context of higher subjective cognitive complaints than objective test performance.

Demographic-Dependent Risk of Developing Severe Novel Psychiatric Disorders after Concussion

Current guidelines for patients experiencing a concussion or mild traumatic brain injury (mTBI) often focus on conservative care and observation. However, mTBI may increase the risk of severe novel psychiatric disorders (NPDs) within 180 days, and long-term management of mTBI should include psychiatric evaluation in patient populations. Retrospective cohort analysis was conducted using 8 years of the Nationwide Readmission Database. All individuals who were admitted for concussion and were readmitted within 180 days were queried. This cohort was then subdivided based on age, sex, and whether they experienced loss of consciousness (LOC) to control for demographic-dependent confounding. A binary decision tree provided recommendations for patients who may be at risk of developing severe NPDs. Analysis included 12,080 patients who experienced concussion. Males and females with LOC had higher rates of depression in all age quartiles within 180 days (p < 0.05). Young females with LOC had increased rates of suicidal ideation (p < 0.01), and those >25 years of age had increased rates of anxiety (p < 0.005). Adult males with LOC had increased rates of suicidal ideation (p < 0.002) and males >75 years of age had increased rates of anxiety at readmission (p < 0.05). Males without LOC had increased rates of depression (p < 0.005), with men in the second quartile also at higher risk of developing anxiety (p < 0.05). Females without LOC showed the fewest number of NPDs at readmission. Concussion may be associated with increased rates of NPDs in the first 6 months following discharge. We use these data to develop recommendations for psychiatric screening of patients with mTBI.

A Genome-wide Association Study for Concussion Risk

PURPOSE

This study aimed to screen the entire genome for genetic markers associated with risk for concussion.

METHODS

A genome-wide association analyses was performed using data from the Kaiser Permanente Research Bank and the UK Biobank. Concussion cases were identified based on electronic health records from the Kaiser Permanente Research Bank and the UK Biobank from individuals of European ancestry. Genome-wide association analyses from both cohorts were tested for concussion using a logistic regression model adjusting for sex, height, weight, and race/ethnicity using allele counts for single nucleotide polymorphisms. Previously identified genes within the literature were also tested for association with concussion.

RESULTS

There were a total of 4064 cases of concussion and 291,472 controls within the databases, with two single nucleotide polymorphisms demonstrating a genome-wide significant association with concussion. The first polymorphism, rs144663795 (P = 9.7 × 10-11; OR = 2.91 per allele copy), is located within the intron of SPATA5. Strong, deleterious mutations in SPATA5 cause intellectual disability, hearing loss, and vision loss. The second polymorphism, rs117985931 (P = 3.97 × 10-9; OR = 3.59 per allele copy), is located within PLXNA4. PLXNA4 plays a key role is axon outgrowth during neural development, and DNA variants in PLXNA4 are associated with risk for Alzheimer's disease. Previous investigations have identified five candidate genes that may be associated with concussion, but none showed a significant association in the current model (P < 0.05).

CONCLUSION

Two genetic markers were identified as potential risk factors for concussion and deserve further validation and investigation of molecular mechanisms.

Preinjury and Postinjury Factors That Predict Sports-Related Concussion and Clinical Recovery Time

OBJECTIVES

To evaluate the relationship between preinjury risk factors (RFs) and subsequent occurrence of concussion and examine whether preinjury RFs or postinjury assessments predict clinical recovery in collegiate athletes.

METHODS

Risk factors (sex, sport, and self-report history of concussion, migraine, attention-deficit disorder, learning disability, depression, and anxiety) and Sport Concussion Assessment Tool (SCAT), depression/anxiety screenings, and neuropsychological testing were obtained before the season. For athletes who sustained concussion, RFs, postinjury SCAT, neuropsychological assessment, and clinical recovery were assessed.

RESULTS

We assessed 1152 athletes (69% male) at baseline and 145 (75% male) after subsequent concussion diagnosis. Only sport type (Wald = 40.29, P = 0.007) and concussion history (Wald = 9.91, P = 0.007) accounted for unique variance in subsequent concussion. Of athletes followed until full recovery, mean days until symptom-free (DUSF) was 9.84 ± 11.11 days (n = 138, median = 5 days, range = 1-86) and mean days until full return to play (DUFRTP) was 20.21 ± 19.17 (n = 98, median = 20.21, range = 4-150). None of the RFs or baseline testing measures were associated with DUSF or DUFRTP (P's > 0.05). After injury, athletes who reported more total symptoms (rs = 0.31, P < 0.001) and higher symptom severity (rs = 0.33, P < 0.001) exhibited longer DUSF. Days until symptom-free correlated with DUFRTP (rs = 0.75, P < 0.001). Among athletes assessed within 2 days after injury, DUSF was associated with Immediate Postconcussion Assessment and Cognitive Test visual motor (rs = -0.31, P = 0.004), reaction time (rs = 0.40, P < 0.001), and symptom score (rs = 0.54, P < 0.001).

CONCLUSIONS

Only sport type and concussion history predicted subsequent occurrence of concussion, and none of the RFs or baseline measures predicted clinical recovery. Immediate postinjury assessments, including symptom number and severity, and select clinical measures predicted longer clinical recovery.

Compensatory Cognitive Strategy Use by Young Adults: A Psychometric Evaluation of Self-Report Measures

This study examined the reliability and validity of scores from questionnaires assessing compensatory cognitive strategy use by young adults. Participants (N = 783; 79.6% women; 77.4% White; Age: M = 18.7 ± 0.9 years) completed the Compensatory Cognitive Strategies Scale (CCSS), Metamemory Questionnaire-Strategies (MMQ-S), Neuro-Quality of Life (Neuro-QoL) v2.0 Short Form-Cognitive Function, and Difficulties in Emotion Regulation Scale (DERS). Reliability estimates were acceptable for the CCSS (α = .85) and MMQ-S (α = .86) in the full sample and comparable in subsamples stratified by gender and self-reported mental health conditions. The CCSS and MMQ-S scores showed evidence for convergent validity (r range: .60 to .70) and discriminant validity in the full sample and subsamples (r with DERS range: .13 to .33). Greater compensatory strategy use had small-to-medium associations with greater subjective cognitive concerns on the Neuro-QOL for the full sample and subsamples (r range: -.19 to -.49). The CCSS and MMQ-S scores showed acceptable properties for use with young adults.

The structure of post-concussion symptoms in adolescent student athletes: confirmatory factor analysis and measurement invariance

Objective: This study examined factor models for the Post-Concussion Symptom Scale (PCSS) at baseline and after suspected sport-related concussion, and measurement invariance from pre-injury to post-injury assessments and across age, gender, and health history groups (e.g., attention-deficit/hyperactivity disorder, psychiatric history). Methods: Adolescent student athletes (ages 13-18) completed a baseline PCSS (n = 39,015; 54.3% boys) and a subsample within 21 days of a suspected concussion (n = 1,554; 56.7% boys) completed a post-injury PCSS. Five models were evaluated for fit and invariance. Results: Confirmatory factor analyses showed good baseline and post-injury model fit for a previously supported four-factor model (i.e., cognitive-sensory, sleep-arousal, vestibular-somatic, and affective), an alternative four-factor model (i.e., cognitive, sleep-arousal, physical, and affective), and an incomplete bifactor model with vestibular-somatic and affective specific factors, along with partial invariance from pre-injury to post-injury assessments. Partial-to-full invariance was established for each model at baseline across demographic and health history groups. Conclusions: Results showed empirical and conceptual support for both PCSS subscales (i.e., cognitive, sleep-arousal, physical, and affective) and a total score for use in pre-injury to post-injury assessments and across demographic and health history groups at baseline. Future normative data, stratified by demographics and health history, could provide more precise symptom assessments for concussion management.

Complicated versus uncomplicated mild traumatic brain injuries: A comparison of psychological, cognitive, and post-concussion symptom outcomes

INTRODUCTION

A complicated mild traumatic brain injury (MTBI) is defined as mild by all clinical severity indicators but is complicated due to a traumatic intracranial abnormality visible on neuroimaging. Researchers have reported mixed findings regarding whether neuropsychological and functional outcomes following complicated MTBI are worse than, or similar to, outcomes following uncomplicated MTBI. This study examined patients referred from a Taiwanese emergency department to a neurosurgical outpatient clinic. Participants with complicated MTBI, uncomplicated MTBI, and those who did not undergo head computed tomography (CT) were compared on psychological, neuropsychological, and post-concussion symptom outcomes within 21 days of injury.

METHOD

Participants with complicated MTBI (n = 42), uncomplicated MTBI (n = 77), and no head CT (n = 172) completed the Paced Auditory Serial Attention Test, Taiwanese Word Sequence Learning Test, a semantic Verbal Fluency Test, the Checklist of Post-Concussion Symptoms, and the Beck Depression and Anxiety Inventories.

RESULTS

No significant differences were observed between groups on any measure. For individual post-concussion symptoms, dizziness, anxiety, and attention difficulty were endorsed more often after uncomplicated MTBIs, but these group differences were not significant after controlling for multiple comparisons.

CONCLUSIONS

Participants with complicated MTBIs did not have worse acute or subacute outcomes than participants with uncomplicated MTBIs or no head CT. These results are consistent with many studies finding comparable outcomes between those with complicated and uncomplicated MTBIs. This study is limited by small sample size and minimal information on intracranial abnormalities, broadly categorizing groups based on positive or negative neuroimaging as opposed to specific lesion types and locations.

Examining the Subacute Effects of Mild Traumatic Brain Injury Using a Traditional and Computerized Neuropsychological Test Battery

This study investigates subacute cognitive effects of mild traumatic brain injury (MTBI) in the Trondheim Mild TBI Study, as measured, in part, by the neuropsychological test battery of the Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI) program, including computerized tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and traditional paper-and-pencil tests. We investigated whether cognitive function was associated with injury severity: intracranial traumatic lesions on neuroimaging, witnessed loss of consciousness (LOC), or post-traumatic amnesia (PTA) >1 h. Further, we explored which of the tests in the CENTER-TBI battery might be associated with the largest subacute effects of MTBI (i.e., at 2 weeks post-injury). We recruited 177 patients with MTBI (16-59 years of age) from a regional trauma center and an outpatient clinic,79 trauma control participants, and 81 community control participants. The MTBI group differed from community controls only on one traditional test of processing speed (coding; p = 0.009, Cliff's delta [Δ] = 0.20). Patients with intracranial abnormalities performed worse than those without on a traditional test (phonemic verbal fluency; p = 0.043, Δ = 0.27), and patients with LOC performed differently on the Attention Switching Task from the CANTAB (p = 0.020, Δ = -0.20). Patients with PTA >1 h performed worse than those with <1 h on 10 measures, from traditional tests and the CANTAB (Δ = 0.33-0.20), likely attributable, at least in part, to pre-existing differences in intellectual functioning between groups. In general, those with MTBI had good neuropsychological outcome 2 weeks after injury and no particular CENTER-TBI computerized or traditional tests seemed to be more sensitive to subtle cognitive deficits.

The Role of Iron, Its Metabolism and Ferroptosis in Traumatic Brain Injury

Traumatic brain injury (TBI) is a structural and physiological disruption of brain function caused by external forces. It is a major cause of death and disability for patients worldwide. TBI includes both primary and secondary impairments. Iron overload and ferroptosis highly involved in the pathophysiological process of secondary brain injury. Ferroptosis is a form of regulatory cell death, as increased iron accumulation in the brain leads to lipid peroxidation, reactive oxygen species (ROS) production, mitochondrial dysfunction and neuroinflammatory responses, resulting in cellular and neuronal damage. For this reason, eliminating factors like iron deposition and inhibiting lipid peroxidation may be a promising therapy. Iron chelators can be used to eliminate excess iron and to alleviate some of the clinical manifestations of TBI. In this review we will focus on the mechanisms of iron and ferroptosis involving the manifestations of TBI, broaden our understanding of the use of iron chelators for TBI. Through this review, we were able to better find novel clinical therapeutic directions for further TBI study.

History of Sport-Related Concussion and Long-Term Clinical Cognitive Health Outcomes in Retired Athletes: A Systematic Review

BACKGROUND

Sport-related concussions (SRCs) are known to have short-term effects on cognitive processes, which can result in diverse clinical presentations. The long-term effects of SRC and repeated exposure to head impacts that do not result in SRC on specific cognitive health outcomes remain unclear.

OBJECTIVES

To synthesize and appraise the evidence base regarding cognitive health in living retired athletes with a history of head-impact exposure or SRC.

DATA SOURCES

A systematic search of the EMBASE, PsycINFO, MEDLINE/PubMed, CINAHL, Cochrane Central Register of Controlled Trials, and Web of Science databases was conducted from inception to April 2018 using common key words and medical subject headings related to 3 components: (1) the participant (eg, retired athlete), (2) the primary outcome measure (eg, cognitive test used), and (3) the secondary outcome measure (eg, history of sport concussion).

STUDY SELECTION

Cross-sectional studies of living retired male or female athletes in which at least 1 cognitive test was used as an outcome measure were included. Two reviewers independently screened studies.

DATA EXTRACTION

Data extraction was performed using Strengthening the Reporting of Observational Studies in Epidemiology guidelines. Methodologic quality was assessed independently by 2 reviewers using the Downs and Black tool.

DATA SYNTHESIS

The search yielded 46 cross-sectional observational studies that were included in a qualitative synthesis. Most included studies (80%, n = 37) were published in the 5 years before our review. A large proportion of these studies (n = 20) included retired American National Football League players. The other research investigated professional, university, high school, and amateur retired athletes participating in sports such as American and Australian football, boxing, field and ice hockey, rugby, and soccer. The total sample consisted of 13 975 participants: 7387 collision-sport athletes, 662 contact-sport athletes, 3346 noncontact-sport athletes, and 2580 participants classified as controls. Compared with control participants or normative data, retired athletes displayed worse performance in 17 of 31 studies (55%) of memory, 6 of 11 studies (55%) of executive function, and 4 of 6 studies (67%) of psychomotor function and increased subjective concerns about cognitive function in 11 of 14 studies (79%). The authors of 13 of 46 investigations (28%) reported a frequency-response relationship, with poorer cognitive outcomes in athletes who had greater levels of exposure to head impacts or concussions. However, these results must be interpreted in light of the lack of methodologic rigor and moderate quality assessment of the included studies.

CONCLUSIONS

Evidence of poorer cognitive health among retired athletes with a history of concussion and head-impact exposure is evolving. Our results suggest that a history of SRC may more greatly affect the cognitive domains of memory, executive function, and psychomotor function. Retired athletes appeared to have increased self-reported cognitive difficulties, but the paucity of high-quality, prospective studies limited the conclusions that could be drawn regarding a cause-and-effect relationship between concussion and long-term health outcomes. Future researchers should consider a range of cognitive health outcomes, as well as premorbid ability, in diverse samples of athletes with or without a history of concussion or head-impact exposure to delineate the long-term effects of sport participation on cognitive functioning.

Remote concussion history does not affect visually-guided reaching in young adult females

Aim:

We examined the long-term effects of concussions in young adult females on visuomotor behavior during a visually-guided reaching task of various complexities.

Materials & methods:

20 females with a history of longer than 6 months since a concussion and 20 healthy females quickly and accurately performed a delayed reach to a previously cued target.

Results:

As both cognitive and motor load increased, task performance decreased for both groups (p < 0.05). However, contrary to our primary hypothesis, no differences in task performance were found between the two experimental groups (p > 0.05).

Conclusion:

The young adult females with a remote history of concussion demonstrated no deficits in visuomotor behavior on an attention-mediated reaching task as compared with control participants.

Current literature is inconclusive regarding the long-term effects of concussion. Some have argued that the differing results are due to many uncontrolled factors in study design. In this study, 20 females with a history of concussion more than 6 months ago and 20 healthy females performed a reaching task under different levels of difficulty. As the reaching task got harder, both groups had greater difficulty doing the task quickly and accurately (p < 0.05). Surprisingly, however, no differences in reaching performance existed between the two groups (p > 0.05). Young adult females with a remote history of concussion demonstrated no greater problems with complicated reaching tasks when compared with control participants when experimental conditions are tightly controlled.

Beyond Measures of Central Tendency: Novel Methods to Examine Sex Differences in Neuropsychological Performance Following Sports-Related Concussion in Collegiate Athletes

OBJECTIVE

The purpose of this study was to examine sex differences in neuropsychological functioning after sports-related concussion using several approaches to assess cognition: mean performance, number of impaired scores, and intraindividual variability (IIV).

METHOD

In the study, 152 concussed college athletes were administered a battery of neuropsychological tests, on average, 10 days post-concussion (SD = 12.75; Mdn = 4 days; Range = 0-72 days). Mean performance was evaluated across 18 individual neuropsychological variables, and the total number of impaired test scores (>1.5 SD below the mean) was calculated for each athlete. Two measures of IIV were also computed: an intraindividual standard deviation (ISD) score and a maximum discrepancy (MD) score.

RESULTS

Analyses of covariance revealed that, compared with males, females had significantly more impaired scores and showed greater variability on both IIV indices (ISD and MD scores) after adjusting for time since injury and post-concussive symptoms. In contrast, no significant effects of sex were found when examining mean neuropsychological performance.

CONCLUSION

Although females and males demonstrated similar mean performance following concussion, females exhibited a greater level of cognitive impairment and larger inconsistencies in cognitive performance than males. These results suggest that evaluating cognitive indices beyond mean neuropsychological scores may provide valuable information when determining the extent of post-concussion cognitive dysfunction.

Cognitive Reserve Moderates Cognitive Outcome After Mild Traumatic Brain Injury

OBJECTIVE

To investigate whether cognitive reserve moderates differences in cognitive functioning between patients with mild traumatic brain injury (MTBI) and controls without MTBI and to examine whether patients with postconcussion syndrome have lower cognitive functioning than patients without postconcussion syndrome at 2 weeks and 3 months after injury.

DESIGN

Trondheim MTBI follow-up study is a longitudinal controlled cohort study with cognitive assessments 2 weeks and 3 months after injury.

SETTING

Recruitment at a level 1 trauma center and at a general practitioner-run, outpatient clinic.

PARTICIPANTS

Patients with MTBI (n=160) according to the World Health Organization criteria, trauma controls (n=71), and community controls (n=79) (N=310).

MAIN OUTCOME MEASURES

A cognitive composite score was used as outcome measure. The Vocabulary subtest was used as a proxy of cognitive reserve. Postconcussion syndrome diagnosis was assessed at 3 months with the British Columbia Postconcussion Symptom Inventory.

RESULTS

Linear mixed models demonstrated that the effect of vocabulary scores on the cognitive composite scores was larger in patients with MTBI than in community controls at 2 weeks and at 3 months after injury (P=.001). Thus, group differences in the cognitive composite score varied as a function of vocabulary scores, with the biggest differences seen among participants with lower vocabulary scores. There were no significant differences in the cognitive composite score between patients with (n=29) and without (n=131) postconcussion syndrome at 2 weeks or 3 months after injury.

CONCLUSION

Cognitive reserve, but not postconcussion syndrome, was associated with cognitive outcome after MTBI. This supports the cognitive reserve hypothesis in the MTBI context and suggests that persons with low cognitive reserve are more vulnerable to reduced cognitive functioning if they sustain an MTBI.

Results of scoping review do not support mild traumatic brain injury being associated with a high incidence of chronic cognitive impairment: Commentary on McInnes et al. 2017

A recently published review of 45 studies concluded that approximately half of individuals who sustain a single mild traumatic brain injury (MTBI) experience long-term cognitive impairment (McInnes et al. Mild Traumatic Brain Injury (mTBI) and chronic cognitive impairment: A scoping review. PLoS ONE 2017;12:e0174847). Stratified by age, they reported that 50% of children and 58% of adults showed some form of cognitive impairment. We contend that the McInnes et al. review used a definition of “cognitive impairment” that was idiosyncratic, not applicable to individual patients or subjects, inconsistent with how cognitive impairment is defined in clinical practice and research, and resulted in a large number of false positive cases of cognitive impairment. For example, if a study reported a statistically significant difference on a single cognitive test, the authors concluded that every subject with a MTBI in that study was cognitively impaired–an approach that cannot be justified statistically or psychometrically. The authors concluded that impairment was present in various cognitive domains, such as attention, memory, and executive functioning, but they did not analyze or report the results from any of these specific cognitive domains. Moreover, their analyses and conclusions regarding many published studies contradicted the interpretations provided by the original authors of those studies. We re-reviewed all 45 studies and extracted the main conclusions from each. We conclude that a single MTBI is not associated with a high incidence of chronic cognitive impairment.

Long-Term Cognitive Performance of Retired Athletes with Sport-Related Concussion: A Systematic Review and Meta-Analysis

Objective: The purpose of this systematic review is to quantitatively estimate (or invest) the impacts of sports-related concussions (SRCs) on cognitive performance among retired athletes more than 10 years after retirement. Methods: Six databases including (MEDLINE, Scopus, Web of Science, SPORTDiscus, CINAHL, and PsycArtilces) were employed to retrieve the related studies. Studies that evaluate the association between cognitive function and the SRC of retired athletes sustaining more than 10 years were included. Results: A total of 11 studies that included 792 participants (534 retired athletes with SRC) were identified. The results indicated that the retired athletes with SRCs, compared to the non-concussion group, had significant cognitive deficits in verbal memory (SMD = -0.29, 95% CI -0.59 to -0.02, I² = 52.8%), delayed recall (SMD = -0.30, 95% CI -0.46 to 0.07, I² = 27.9%), and attention (SMD = -0.33, 95% CI -0.59 to -0.06, I² = 0%). Additionally, meta-regression demonstrated that the period of time between testing and the last concussion is significantly associated with reduced verbal memory (β = -0.03681, p = 0.03), and increasing age is significantly associated with the verbal memory (β = -0.03767, p = 0.01), immediate recall (β = -0.08684, p = 0.02), and delay recall (β = -0.07432, p = 0.02). Conclusion: The retired athletes who suffered from SRCs during their playing career had declined cognitive performance in partial domains (immediate recall, visuospatial ability, and reaction time) later in life.

Postconcussion Academic Support in Children Who Attend a Primary Care Provider Follow-up Visit after Presenting to the Emergency Department

OBJECTIVE

To examine whether a primary care provider (PCP) follow-up visit after emergency department evaluation of concussion improved the children's likelihood of receiving academic support.

STUDY DESIGN

This was a prospective cohort study. Concussed children, aged 8-18 years, presenting to a regional pediatric trauma center emergency department (n = 160) were contacted 7 and 30 days after injury to gather data on PCP follow-up, symptoms, quality of life, and receipt of academic support instituted after and because of the concussion. Bivariate comparisons of demographics, concussion characteristics, quality of life, and symptoms were made between children who did and did not receive support using independent samples t tests, Wilcoxon rank sum tests, or χ² tests. ORs and 95% CIs were calculated using multivariable logistic regression with backwards elimination to test the association between attending an outpatient follow-up visit and the receipt of academic support for variables where P < .2 in bivariate comparisons.

RESULTS

Overall, 51.3% (n = 82) received academic support; of these, 84.2% attended a follow-up visit compared with 71.8% of 78 children who attended a follow-up visit but did not receive support (P = .06). Children who received support were more likely to have commercial insurance; experience a sports-related injury mechanism; have parents whose primary language was English; suffer from learning disabilities and migraines; and be non-Hispanic (P < .05). There was no association between attending a follow-up visit and receipt of academic support (adjusted OR 1.83; 95% CI 0.75-4.45).

CONCLUSIONS

Although the majority of children received academic support postconcussion, accommodations were associated with several demographic, medical history, and injury characteristics, but not attending a PCP follow-up visit.

Treatments and rehabilitation in the acute and chronic state of traumatic brain injury

Traumatic brain injury (TBI) is a major cause of acquired disability globally, and effective treatment methods are scarce. Lately, there has been increasing recognition of the devastating impact of TBI resulting from sports and other recreational activities, ranging from primarily sport-related concussions (SRC) but also more severe brain injuries requiring hospitalization. There are currently no established treatments for the underlying pathophysiology in TBI and while neuro-rehabilitation efforts are promising, there are currently is a lack of consensus regarding rehabilitation following TBI of any severity. In this narrative review, we highlight short- and long-term consequences of SRCs, and how the sideline management of these patients should be performed. We also cover the basic concepts of neuro-critical care management for more severely brain-injured patients with a focus on brain oedema and the necessity of improving intracranial conditions in terms of substrate delivery in order to facilitate recovery and improve outcome. Further, following the acute phase, promising new approaches to rehabilitation are covered for both patients with severe TBI and athletes suffering from SRC. These highlight the need for co-ordinated interdisciplinary rehabilitation, with a special focus on cognition, in order to promote recovery after TBI.

The Ivy League-Big Ten Epidemiology of Concussion Study: A Report on Methods and First Findings

BACKGROUND

Little is known about the nature of concussion injury among university student-athletes, including concussion incidence and rates across sports, the mechanisms of injury, the type of activity during competition or practice, and the time to return to academics, return to sport, and symptom resolution.

PURPOSE

To describe methods of the Ivy League-Big Ten Epidemiology of Concussion Study and first epidemiologic findings.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

A prospective cohort study was conducted with data accrued through a surveillance system that was launched in the 2013-2014 athletic season. Surveillance continues to operate by detecting and collecting sport-related concussion (SRC) cases and non-SRC cases in addition to outcomes among university student-athletes.

RESULTS

A total of 1922 cases of SRC (649 women, 1004 men) among athletes from 27 sports, including varsity sports and club rugby, were enrolled during the 5 athletic seasons from 2013-2014 through 2017-2018. American football had the most cases (n = 495, 25.8%), followed by women's rugby (n = 199, 6.2%), men's ice hockey (n = 106, 5.5%), men's lacrosse (n = 105, 5.5%), women's soccer (n = 103, 5.4%), wrestling (n = 93, 4.8%), and men's soccer (n = 89, 4.6%), and women's ice hockey (n = 78, 4.1%). The highest overall concussion rates occurred in women's lacrosse (1.35 concussions per 1000 athletic exposures [AEs]) and football (1.26 per 1000 AEs). Rates of concussion were generally higher during competition than practice and were highest during wrestling competition (4.06 per 1000 AEs) and second highest during football competition (3.68 per 1000 AEs). The median number of concussion symptoms was 7. Time to symptom resolution was longer for athletes with ≥7 symptoms versus <7 ( P < .001) but did not differ across the 4 sports with rules comparable by sex and did not differ significantly between women and men (median, 8 vs 9 days, respectively). Women and men did not differ in days to return to academics, exertion activities, or competition.

CONCLUSION

This multisite collaborative endeavor has produced a robust database yielding novel opportunities to better understand the epidemiology of concussion among university student-athletes participating in a variety of sports. Given the setting and number of cases, these findings add to our understanding of SRC and are the first of many that will be generated over the coming years from this large study that continues in its sixth year.

A systematic review of sex differences in concussion outcome: What do we know?

Objective: The purpose of this review was to examine sex differences in concussion, or mild traumatic brain injury (mTBI) outcome, updating previous critical reviews of the literature. Method: Within adult human studies, we reviewed a wide range of concussion outcome variables: prevalence of concussion, injury characteristics, postconcussion symptom trajectories and psychiatric distress, neuropsychological performance, and neuroimaging findings. Sports-related concussion, civilian, and military samples were included in the review. Results: Given the robust concussion literature, there is a relative paucity of research addressing sex differences following concussion. The majority of available studies focused on sports-related concussion, with fewer studies targeting other civilian causes of concussion or military-related concussion in females. Prevalence of concussion was generally reported to be higher in females than males. Although symptom reporting largely showed a pattern for females to report greater overall symptoms than males, examining individual symptoms or symptom clusters resulted in mixed findings between the sexes. Neuropsychological studies generally showed females performing more poorly than males on measures of visual memory following concussion, though this finding was not consistently reported. Conclusion: Research examining sex differences in humans following concussion, in general, is in its infancy, and exploration of sex differences in studies outside of the sports concussion domain is particularly nascent. Given the increased prevalence of concussion and potential higher symptom reporting among women, ongoing research is necessary to better understand the role of biological sex on outcome following concussion. Understanding sex differences has important implications for assessment, management, and treatment of concussion.

Clinical Findings in a Multicenter MRI Study of Mild TBI

Background: Uncertainty continues to surround mild traumatic brain injury (mTBI) diagnosis, symptoms, prognosis, and outcome due in part to a lack of objective biomarkers of injury and recovery. As mTBI gains recognition as a serious public health epidemic, there is need to identify risk factors, diagnostic tools, and imaging biomarkers to help guide diagnosis and management. Methods: One hundred and eleven patients (15-50 years old) were enrolled acutely after mTBI and followed with up to four standardized serial assessments over 3 months. Each encounter included a clinical exam, neuropsychological assessment, and magnetic resonance imaging (MRI). Chi-square and linear mixed models were used to assess changes over time and determine potential biomarkers of mTBI severity and outcome. Results: The symptoms most frequently endorsed after mTBI were headache (91%), not feeling right (89%), fatigue (86%), and feeling slowed down (84%). Of the 104 mTBI patients with a processed MRI scan, 28 (27%) subjects had white matter changes which were deemed unrelated to age, and 26 of these findings were deemed unrelated to acute trauma. Of the neuropsychological assessments tested, 5- and 6-Digit Backward Recall, the modified Balance Error Scoring System (BESS), and Immediate 5-Word Recall significantly improved longitudinally in mTBI subjects and differentiated between mTBI subjects and controls. Female sex was found to increase symptom severity scores (SSS) at every time point. Age ≥ 25 years was correlated with increased SSS. Subjects aged ≥ 25 also did not improve longitudinally on 5-Digit Backward Recall, Immediate 5-Word Recall, or Single-Leg Stance of the BESS, whereas subjects < 25 years improved significantly. Patients who reported personal history of depression, anxiety, or other psychiatric disorder had higher SSS at each time point. Conclusions: The results of this study show that 5- and 6-Digit Backward Recall, the modified BESS, and Immediate 5-Word Recall should be considered useful in demonstrating cognitive and vestibular improvement during the mTBI recovery process. Clinicians should take female sex, older age, and history of psychiatric disorder into account when managing mTBI patients. Further study is necessary to determine the true prevalence of white matter changes in people with mTBI.

Sex Differences in Common Sports Injuries

Common sports injuries include bone stress injuries (BSIs), anterior cruciate ligament (ACL) injuries, and concussions. Less commonly recognized are the specific sex differences in epidemiology, risk factors, and outcomes of these conditions by sex. An understanding of these factors can improve their clinical management, from prescribing appropriate prehabilitation to guiding postinjury rehabilitation and return to play. This narrative review summarizes the sex differences in the diagnosis and management of BSIs, ACL injuries, and concussions. Although BSIs are more common in female athletes, risk factors for both sexes include prior injury and relative energy deficiency in sport (RED-S). Risk factors in female athletes include smaller calf girth, femoral adduction, and higher rates of loading. Female athletes are also at greater risk for developing ACL injuries in high school and college, but their injury rate is similar in professional sports. Increased lateral tibial slope, smaller ACL size, and suboptimal landing mechanics are additional risk factors more often present in female athletes. Male athletes are more likely to have ACL surgery and have a higher rate of return to sport. Concussions occur more commonly in female athletes; however, female athletes are also more likely to report concussions. Male athletes more commonly sustain concussion through contact with another player. Female athletes more commonly sustain injury from contact with playing equipment. Managing post-concussion symptoms is important, and female athletes may have prolonged symptoms. An understanding of the sex-specific differences in these common sports injuries can help optimize their prehabilitation and rehabilitation. LEVEL OF EVIDENCE: IV.

Sex-related responses after traumatic brain injury: Considerations for preclinical modeling

Traumatic brain injury (TBI) has historically been viewed as a primarily male problem, since men are more likely to experience a TBI because of more frequent participation in activities that increase risk of head injuries. This male bias is also reflected in preclinical research where mostly male animals have been used in basic and translational science. However, with an aging population in which TBI incidence is increasingly sex-independent due to falls, and increasing female participation in high-risk activities, the attention to potential sex differences in TBI responses and outcomes will become more important. These considerations are especially relevant in designing preclinical animal models of TBI that are more predictive of human responses and outcomes. This review characterizes sex differences following TBI with a special emphasis on the contribution of the female sex hormones, progesterone and estrogen, to these differences. This information is potentially important in developing and customizing TBI treatments.

Effects of concussions on visually guided motor actions: A literature review

Athletes must be able to successfully navigate the soccer pitch or hockey rink to win the game, requiring maximal cognitive resources to successfully compete. Concussions potentially deplete these resources, and the long-term impact of concussions on an individual's goal-directed visually guided behavior continues to elude the scientific community. While the acute effects on cognition and the motor system have been elucidated elsewhere, long-term effects on performance have been less clear. Additionally, most investigations into long-term postinjury motor behaviors have focused on balance and gait, with little focus on functional upper extremity movements. These arm movements require both cognitive and motor functions to successfully complete the task, such as visually guided reaching, and have received little attention. This review examines the current state of the literature to date on the long-term effects of concussions on cognitive and motor deficits affecting visuomotor behavior.