Victoria C. Merritt

Neuropsychological Outcome from Blast versus Non-blast: Mild Traumatic Brain Injury in U.S. Military Service Members

The purpose of this study was to compare the neuropsychological outcome from blast-related versus non-blast related mild traumatic brain injury (MTBI). Participants were 56 U.S. military service members who sustained an MTBI, divided into two groups based on mechanism of injury: (a) non-blast related (Non-blast; n = 21), and (b) blast plus secondary blunt trauma (Blast Plus; n = 35). All participants had sustained their injury in theatre whilst deployed during Operation Iraqi Freedom or Operation Enduring Freedom. Patients had been seen for neuropsychological evaluation at Walter Reed Army Medical Center on average 4.4 months (SD = 4.1) post-injury. Measures included 14 clinical scales from the Personality Assessment Inventory (PAI) and 12 common neurocognitive measures. For the PAI, there were no significant differences between groups on all scales (p > .05). However, medium effect sizes were found for the Depression (d = .49) and Stress (d = .47) scales (i.e., Blast Plus > Non-blast). On the neurocognitive measures, after controlling for the influence of psychological distress (i.e., Depression, Stress), there were no differences between the Non-blast and Blast Plus groups on all measures. These findings provide little evidence to suggest that blast exposure plus secondary blunt trauma results in worse cognitive or psychological recovery than blunt trauma alone. (JINS, 2012, 18, 595-605).

Neuropsychological Outcome from Uncomplicated Mild, Complicated Mild, and Moderate Traumatic Brain Injury in US Military Personnel

This study compared the neuropsychological outcome in military personnel following mild-to-moderate traumatic brain injury (TBI). Participants were 83 service members divided into three injury severity groups: uncomplicated mild TBI (MTBI; n = 24), complicated MTBI (n = 17), and moderate TBI (n = 42). Participants were evaluated within 6 months following injury (73% within 3 months) using neurocognitive testing and the Personality Assessment Inventory (PAI). There were no significant differences between the three groups on the majority of neurocognitive measures. Similarly, there were no significant differences between the three groups on the majority of PAI clinical scales (all p > .05), with the exception of two scales. The uncomplicated MTBI group had significantly higher scores on the Anxiety-Related Disorders and Aggression scales compared with the complicated MTBI group, but not the moderate TBI group. Overall, these results suggest that within the first 6 months post injury, there were few detectable differences in the neuropsychological outcome following uncomplicated MTBI, complicated MTBI, or moderate TBI in this military sample.

Apolipoprotein E (APOE) ϵ4 Allele Is Associated with Increased Symptom Reporting Following Sports Concussion.

Exploring the relationship between genetic factors and outcome following brain injury has received increased attention in recent years. However, few studies have evaluated the influence of genes on specific sequelae of concussion. The purpose of this study was to determine how the ϵ4 allele of the apolipoprotein E (APOE) gene influences symptom expression following sports-related concussion. Participants included 42 collegiate athletes who underwent neuropsychological testing, including completion of the Post-Concussion Symptom Scale (PCSS), within 3 months after sustaining a concussion (73.8% were evaluated within 1 week). Athletes provided buccal samples that were analyzed to determine the make-up of their APOE genotype. Dependent variables included a total symptom score and four symptom clusters derived from the PCSS. Mann-Whitney U tests showed higher scores reported by athletes with the ϵ4 allele compared to those without it on the total symptom score and the physical and cognitive symptom clusters. Furthermore, logistic regression showed that the ϵ4 allele independently predicted those athletes who reported physical and cognitive symptoms following concussion. These findings illustrate that ϵ4+ athletes report greater symptomatology post-concussion than ϵ4- athletes, suggesting that the ϵ4 genotype may confer risk for poorer post-concussion outcome. (JINS, 2016, 22, 89-94).

Premorbid predictors of postconcussion symptoms in collegiate athletes

Introduction: In recent years, the sports community has been faced with the challenge of determining when it is safe to return concussed athletes to play. Given that return-to-play decisions are partially dependent upon athletes’ endorsement of symptoms, better understanding what factors contribute to the presence of symptoms following concussion is crucial. The purpose of the present study was to better characterize the symptoms that athletes endorse at baseline and to determine what impact various premorbid (or preinjury) characteristics have on the presence and severity of postconcussion symptoms in the acute injury period following concussion. Method: Two groups of participants with similar ages and levels of education were examined: athletes at baseline (N = 702) and postconcussion (N = 55). Athletes were administered a comprehensive battery of neuropsychological tests, consisting of neurocognitive and neurobehavioral measures, at both time periods. The main outcome measure was the Post-Concussion Symptoms Scale (PCSS). A factor analysis was conducted on the participants’ baseline PCSS data to determine the factor structure of the PCSS, and separate logistic regression analyses were conducted that examined the baseline PCSS symptom clusters (derived from the factor analysis), demographic variables, and baseline neurocognitive variables as predictors of dichotomized postconcussion PCSS total scores (i.e., low versus high symptom reporting following concussion). Results: Four distinct clusters emerged from the factor analysis measuring cognitive, physical, affective, and sleep symptoms. Logistic regression results indicated that the physical and affective symptom clusters at baseline reliably predicted athletes’ postconcussion symptom group, as did sex and the neurocognitive composite score. Conclusions: These findings show that certain baseline characteristics of athletes confer risk for greater symptomatology postconcussion. Knowledge of these risk factors can assist the management and treatment of sports-related concussion.

Injury-related predictors of symptom severity following sports-related concussion

Introduction: Decisions regarding return to play after sports-related concussion partially revolve around athletes’ self-reported symptoms. Given this emphasis on symptoms, it would be beneficial to be able to identify characteristics that could predict which athletes may be susceptible to developing an increase in postconcussion symptoms following head injury. The purpose of this study was to describe the symptoms that athletes endorse immediately following concussion and to determine what impact injury-related characteristics have on the development of postconcussion symptoms within the first week following concussion. Method: Participants included 54 collegiate athletes who sustained concussions and were referred to our concussion management program for postconcussion testing. The main outcome measures included the Post-Concussion Symptom Scale and an interview querying athletes’ retrospective symptoms over time, starting immediately postinjury. Results: Descriptive statistics revealed that the most common immediate symptoms following concussion include dizziness (endorsed by 83.6% of the sample), headache (65.5%), feeling in a fog (61.8%), and visual disturbance (60.0%). Logistic regression analyses indicated that retrograde and anterograde amnesia, as well as loss of consciousness, were not significantly predictive of postconcussion symptoms within one week following concussion (p > .05). However, the total symptom score assessed immediately postinjury, in addition to endorsing immediate headache symptoms following concussion, reliably predicted a higher level of symptom reporting in the first week following concussion (p < .05). Finally, receiver-operating characteristic (ROC) curve analysis, using 80% sensitivity to predict the high postconcussion symptom group, established cutoff scores of 7.5 for the immediate total symptom score and 0.5 for immediate headache. Conclusions: These findings demonstrate the importance of evaluating symptoms immediately following concussion. Athletes who endorse more immediate postconcussion symptoms, especially headache symptoms, may be at risk for greater and more severe postconcussion symptoms within the first week following concussion. The present findings have implications for the management and treatment of sports-related concussions.

Resilience and symptom reporting following mild traumatic brain injury in military service members

Abstract Primary objective: The purpose of this study was to examine the relationship between resilience and symptom reporting following mild traumatic brain injury (mTBI). It was hypothesized that, as resilience increases, self-reported symptoms would decrease. Research design: Cross-sectional design. Methods and procedures: Participants were 142 US military service members who sustained a mTBI, divided into three resilience groups based on participants’ responses on the Response to Stressful Experiences Scale: Moderate (n = 42); High (n = 51); and Very High (n = 49). Participants completed the Neurobehavioral Symptom Inventory (NSI) and PTSD Checklist–Civilian Version (PCL-C) within 12 months following injury. Main outcomes and results: There were significant main effects for the NSI total score, cognitive cluster and affective cluster, as well as for the PCL-C total score, avoidance cluster and hyperarousal cluster. Pairwise comparisons revealed that there was a negative relationship between resilience and self-reported symptoms overall. Specifically, participants with higher resilience reported fewer post-concussion and PTSD-related symptoms than participants with lower levels of resilience. Conclusions: These findings underscore the important role that resilience plays in symptom expression in military service members with mTBI and suggest that research on targeted interventions to increase resilience in the acute phase following injury is indicated.

Relationship between the apolipoprotein E gene and headache following sports-related concussion

ABSTRACT Introduction: Headache is one of the most commonly reported and longest lasting symptoms that concussed athletes report, yet the etiology of headache symptoms following concussion is not entirely clear. The purpose of this study was to determine whether the e4 allele of the apolipoprotein E (APOE) gene influences the presence and severity of postconcussion headache. Method: Participants were composed of 45 concussed athletes and 43 healthy/nonconcussed athletes who were involved in a clinically based sports concussion management program. All athletes completed the Post-Concussion Symptom Scale (PCSS). The “headache” symptom from the PCSS was the primary outcome variable. Buccal samples were collected and analyzed to determine APOE genotype. Results: A significantly greater proportion of concussed e4+ athletes than e4– athletes endorsed headache. Furthermore, concussed e4+ athletes endorsed more severe headaches than e4– athletes. When examining the healthy/nonconcussed sample (i.e., athletes at baseline), results showed no differences between e4 allele groups with respect to the presence and severity of headache. Conclusions: These findings show that when compared to concussed e4– athletes, e4+ athletes are more likely to (a) endorse postconcussion headache and (b) report more severe headache symptoms following concussion. Conversely, it appears that the e4 allele does not influence baseline reports of headache. Thus, results suggest that those with the e4 genotype may be at a higher risk for experiencing headache-related difficulties only after a concussion is sustained.

The influence of the apolipoprotein E (APOE) gene on subacute post-concussion neurocognitive performance in college athletes

Objective The purpose of this study was to determine whether the ε4 allele of the APOE gene influences neurocognitive outcome following sports-related concussion. It was hypothesized that participants with an ε4 allele would show poorer neurocognitive performance and greater neurocognitive variability than those without an ε4 allele. Method Participants included 57 concussed collegiate athletes (77.2% male) who participated in a concussion management program at a large university. All athletes underwent a comprehensive neuropsychological assessment and provided a DNA sample for determination of their APOE genotype. The test battery included measures sensitive to concussion, covering the broad domains of learning and memory, attention, processing speed, and executive functions. Results The sample was divided into ε4 + (n = 20) and ε4 - (n = 37) groups. No significant differences were found between athletes with and without an ε4 allele when examining mean neurocognitive standardized scores (all p > .05; d = 0.16-0.18). However, athletes with an ε4 allele were more likely to show a greater number of impaired neurocognitive scores post-injury compared to athletes without an ε4 allele, χ2(1, N = 57) = 3.96, p = < .05, φ = 0.26. Additionally, athletes with an ε4 allele demonstrated greater neurocognitive variability than athletes without an ε4 allele, t(55) = -2.04, p < .05, d = 0.53. Conclusions This research furthers our understanding of how genetic factors uniquely contribute to neurocognitive performance differences following concussion. Our findings suggest a possible relationship between the ε4 allele and post-concussion impairment, as well as between the ε4 allele and neurocognitive performance variability, suggesting that the ε4 genotype may be a risk factor for less efficient cognitive processing in concussed athletes.

The Return-to-Play Incentive and the Effect of Motivation on Neuropsychological Test-Performance: Implications for Baseline Concussion Testing

Athletes may be less engaged in baseline cognitive testing in the absence of a powerful return-to-play incentive. The present study sought to evaluate whether athletes’ level of motivation (1) influences baseline test performance and (2) changes across pre- and post-injury assessments. We found a significant relationship between examiners’ ratings of athletes motivation toward testing and baseline cognitive test performance. Athletes, but not controls, demonstrated increased motivation between tests. These findings suggest that baseline test performance may underestimate true premorbid abilities for a subset of athletes.

Personality factors and symptom reporting at baseline in collegiate athletes.

The purpose of this study was to evaluate the relationship between personality and symptom reporting at baseline in collegiate athletes. Participants were 759 athletes who completed the Post-Concussion Symptom Scale and NEO-Five Factor Inventory. Results showed that neuroticism and agreeableness personality dimensions were predictive of athletes’ symptom reports at baseline.