The characteristics of patients who do not seek medical treatment for traumatic brain injury

Prevalence and Correlates of Suspected and Diagnosed Traumatic Brain Injuries among US School-Aged Children

Objective

To (1) estimate the lifetime prevalence of suspected and diagnosed traumatic brain injury (TBI) based on parent report overall and select sociodemographic characteristics; and (2) describe differences in prevalence of health conditions and health-related risk factors by whether a child had a lifetime history of diagnosed TBI.

Study design

We analyzed data from the 2020 National Survey of Children's Health, a cross-sectional address-based survey of US households. A categorical variable was created on the basis of parent responses to 3 questions inquiring about their suspicion of their child having a brain injury, if they sought medical care, and if the health care provider provided a diagnosis. Parents also were asked to report on their child's additional health conditions, functional indicators, school and social factors, and health care access and service use.

Results

The prevalence of lifetime diagnosed TBI was 4.2% (95% CI 3.8-4.5). Children with a parent-reported lifetime history of diagnosed TBI were more likely to have a variety of health conditions, special health care needs, disabilities, activity limitations, missed days of school, and unmet care coordination needs, compared with those without a history. However, they were more likely to have a usual source of sick care and to receive more health-related services.

Conclusions

For school-aged children, a history of TBI is associated with parent-reported health needs and conditions, as well as missed days from school. It is particularly important for parents to seek care when they suspect their child has experienced a TBI to receive a diagnosis and monitor the impacts of the TBI.

Emotions in search of words: Does alexithymia predict treatment outcome in chronic musculoskeletal pain?

Chronic pain, with its complex and multidimensional nature, poses significant challenges in identifying effective long-term treatments. There is growing scientific interest in how psychopathological and personality dimensions may influence the maintenance and development of chronic pain. This longitudinal study aimed to investigate whether alexithymia can predict the improvement of pain severity following a treatment-as-usual programme for chronic musculoskeletal pain over and above psychological cofactors (emotional distress, catastrophizing, and self-efficacy). A consecutive sample of 129 patients with diagnosed chronic musculoskeletal pain referred to two tertiary care centres was recruited and treated for 16 weeks. Clinical pain, psychological distress, self-efficacy, catastrophizing, and alexithymia were assessed with validated self-report measures at the first medical visit (T0) and at 16-week follow-up (T1). Compared with non-responder patients (n = 72, 55.8%), those who responded (i.e., reduction of >30% in pain severity; n = 57, 44.2%) reported an overall improvement in psychological variables except alexithymia. Alexithymia showed relative stability between baseline and follow-up within the entire sample and remained a significant predictor of treatment outcome even when other predictive cofactors (i.e., pain interference, depressive symptoms, and catastrophizing) were considered simultaneously. Our results suggest that identifying patients with a co-occurrence between alexithymia, depressive symptoms, catastrophizing, and the stressful experience of chronic pain can be clinically relevant in pain prevention and intervention programs.

Diagnostic Accuracy of SPECT for Mild Traumatic Brain Injury: A Systematic Review and Meta-analysis

PURPOSE

This study examines the diagnostic accuracy of brain perfusion SPECT for mild traumatic brain injury (mTBI).

PATIENTS AND METHODS

A systematic review and meta-analysis was performed according to PRISMA guidelines (PROSPERO: CRD42023484636). Five databases were searched for studies evaluating brain perfusion SPECT in adult patients with mTBI (GCS 13-15). Study quality was assessed using a modified QUADAS-2 tool. A meta-analysis was performed to pool proportions of hypoperfusion abnormalities across brain lobes.

RESULTS

Of 4735 records, 22 studies (5 longitudinal [40% high quality], 17 cross-sectional [24% high quality]) were included totaling 800 patients (mean age, 37.4 ± 12.6 years; 36.4% female). Meta-analysis of proportions indicated that the frontal lobe most frequently showed hypoperfusion on brain perfusion SPECT (pooled proportion 40.1% [95% confidence interval, 31.2% to 49.8%], 99/254, I2 = 54.5%), followed by the temporal lobe (26.1% [95% confidence interval, 19.9% to 33.6%], 68/254, I2 = 30.7%). Several studies found that hypoperfusion abnormalities were associated with neuropsychological findings. Also, brain perfusion SPECT could detect abnormalities not seen on MRI. Abnormalities in perfusion on brain perfusion SPECT may be more readily detected with a quantitative assessment compared with a visual assessment alone, although there appears to be no consensus on the optimal method for image interpretation. Evidence evaluating the sensitivity and specificity of brain perfusion SPECT for mTBI was limited. Using the GRADE framework, the evidence was rated as low.

CONCLUSIONS

Although perfusion abnormalities can be seen in patients with mTBI, commonly in the frontal and temporal lobes, the findings are nonspecific and may derive from various factors. Ultimately, brain perfusion SPECT provides additional information for mTBI, but the final added value for the detection of mTBI is unknown.

Sport-Specific Recovery Trajectories for NCAA Collegiate Athletes Following Concussion

The recovery trajectories of collegiate athletes with sport-related concussion (SRC) are well characterized in contact/collision sports but are less well understood in limited contact sports with lower risk, reducing the ability of clinicians to effectively manage the return-to-play (RTP) process. The current study investigated the time to asymptomatic and RTP across a broad range of male and female collegiate sports and sought to group sports by recovery intervals. Data from the Concussion Assessment, Research and Education (CARE) Consortium included 1049 collegiate athletes who sustained a SRC while participating in game or practice/training of their primary sport. Injury setting and subsequent clinical presentation data were obtained. Survival analysis using the Cox Proportional Hazard model estimated the median recovery times for each sport. Optimal univariate K-means clustering grouped sports into recovery categories. Across all sports, median time to asymptomatic following SRC ranged from 5.9 (female basketball) to 8.6 days (male wrestling). Median RTP protocol duration ranged from 4.9 days (female volleyball) to 6.3 days (male wrestling). Median total RTP days ranged from 11.2 days (female lacrosse) to 16.9 days (male wrestling). Sport clusters based on recovery differences in time to asymptomatic (3) and RTP protocol duration (2) were identified. The findings from this study of a large sample of more than 1000 NCAA collegiate athletes with SRC show there exists ranges in recovery trajectories. Clinicians can thus manage athletes with similar guidelines, with individualized treatment and recovery plans.

Neuropathological mRNA Expression Changes after Single Mild Traumatic Brain Injury in Pigs

Traumatic brain injury (TBI) is a public health concern, with an estimated 42 million cases globally every year. The majority of TBIs are mild TBIs, also known as concussion, and result from the application of mechanical forces on the head. Most patients make a complete recovery and mortality is rare; therefore, studies investigating cellular changes after mild TBI in a clinical setting are limited. To address this constraint, our group utilized a pig model of closed-head rotational acceleration-induced TBI, which recreated the biomechanical loading parameters associated with concussion on a large gyrencephalic brain similar to humans. While our previous research has focused on immunohistochemical characterization of neuropathology, the current study utilized transcriptomic assays to evaluate an array of TBI-induced neurodegenerative analytes. Pigs subjected to mild TBI were survived for 3 days post-injury (DPI) (n = 3), 30 DPI (n = 3), or 1 year post-injury (YPI) (n = 3) and compared to animals undergoing a sham procedure (n = 8). RNA was isolated from whole coronal sections of fixed tissue and multiplexed on a Nanostring neuropathology panel. Differential expression analysis revealed 11 differentially expressed genes at 3 DPI versus sham, including downregulation of the synaptotagmin calcium sensor gene (SYT1), upregulation of the neurofibromin gene (NF1), and upregulation of the Alzheimer's disease-associated receptor gene (SORL1). There were no differentially expressed genes at 30 DPI or 1 YPI compared to shams. Additionally, high-magnitude undirected global significance scores (GSS) were detected at 3 DPI for chromatin modification and autophagy gene sets, and at 30 DPI for cytokine gene sets, while many dysregulated gene sets were highlighted by directed GSSs out to 1 YPI. This study adds to a growing body of literature on transcriptomic changes in a clinically relevant large animal model of closed-head TBI, which highlights potential therapeutic targets following mild TBI.

Sport and Recreation Related Concussion in Children: National Concussion Surveillance System

INTRODUCTION

Concussions sustained during sports and recreational activities are a concern for young athletes. The purpose of this study was to estimate past 12-month sport- and recreation-related (SRR) traumatic brain injuries (TBIs) among a sample of children.

METHODS

Pilot data from the Centers for Disease Control and Prevention's National Concussion Surveillance System were analyzed. National Concussion Surveillance System utilized a cross-sectional random-digit-dial telephone survey using computer-assisted telephone interviewing to collect self/proxy-reported data from 2018 to 2019. Adults with children aged 5-17 in the household were asked about head injuries sustained by their children. Estimates were stratified by sociodemographic and injury circumstance characteristics. Data analysis occurred from April 2022 to July 2023.

RESULTS

Utilizing a tiered case definition developed by the Centers for Disease Control and Prevention, an estimated 6.9% (95% confidence interval [CI], 6.0%-7.8%) of the sample's 5-17-year-old children sustained at least one probable or possible SRR-TBI in the previous 12 months; 3.3% (95% CI, 2.7%-4.0%) of the children sustained at least one probable SRR-TBI. An estimated 63.6% (95% CI, 58.1%-69.0%) of all reported TBIs were attributed to SRR activities. Of the SRR-TBIs reported, 41.1% (95% CI, 33.0%-49.2%) were experienced while playing contact sports. Symptoms did not resolve for 8 or more days or had not resolved at the time of the interview for 18.1% (95% CI, 13.0%-23.1%) of the children's most recent SRR-TBI.

CONCLUSIONS

Many proxy-reported TBIs among children aged 5-17 years were due to sports and recreational activities. Athletic trainers and healthcare providers can play a role in the prevention, identification, and management of SRR-TBIs in their respective environments.

Who is seeking information about traumatic brain injury? Characterizing online course participants

Accessible, up-to-date information on traumatic brain injury (TBI) can be challenging to find and is needed to address TBI knowledge gaps and improve outcomes for people who experience a TBI. The Understanding TBI Massive Open Online Course (TBI MOOC) was developed to increase TBI knowledge across a diverse global audience. We sought to characterize the TBI MOOC participant cohort, to understand the reach of the course among this target audience. Examining the characteristics of TBI MOOC enrollees showed that participants came from a wide range of demographic backgrounds, had a variety of TBI experiences and had multiple reasons for enrolling in the MOOC. The majority of course participants shared some characteristics with other groups of health information seekers. Four distinct demographic profiles were identified among TBI MOOC participants (education seekers, TBI-aware participants, TBI care providers and retirees) using a novel approach combining chi-squared tests and network modularity. Participants assigned to the TBI-aware and retiree profiles were most likely to complete all modules of the MOOC, and the TBI-aware profile was more highly represented in more recent iterations of the MOOC. Together, these data indicate that the TBI MOOC provided information to a wide range of people, and particularly engaged participants with personal or family experience of TBI. However, engagement with this course was minimal among some hard-to-reach populations, including men and people with low levels of education, indicating that additional strategies are needed to ensure equity in health promotion.

Comparison of concordance and predictive validity of head injuries from parental reports and medical records

OBJECTIVE

To examine agreement between parental reports of head injury and evidence of head injury in medical records and to compare these two measures in predicting early conduct disorder (CD).

DESIGN AND SETTING

Parent survey data was compared with records of child head injury from the National Health Services Register (Régie de l'assurance maladie du Québec, RAMQ) administrative database.

PARTICIPANTS

Children (N = 685) ages 6-9 with and without CD. There were 147 children with RAMQ recorded head injury and 39 children with parent-reported head injury.

MAIN MEASURES

Indication of one or more head injury before 6 years of age as reported by parents and/or as noted in medical data. Early CD (present by age 9) according to parents and/or teachers.

RESULTS

Results indicated poor agreement between the two forms of reporting κ = .161 (95% CI, .083 to .239), p < 0.001. Medical data significantly predicted the presence of CD in children, with a RAMQ coded head injury suggesting a child was 1.88 times more likely to have CD. Parent reports of head injuries did not significantly predict CD. Conclusion: Medical data should be prioritized in research addressing pediatric head injury, given that parent reports may fail to capture incidence of injury and therefore may be less predictive of other known correlates of head injury.

Incidence of Traumatic Brain Injury in a Longitudinal Cohort of Older Adults

Importance

Traumatic brain injury (TBI) occurs at the highest rate in older adulthood and increases risk for cognitive impairment and dementia.

Objectives

To update existing TBI surveillance data to capture nonhospital settings and to explore how social determinants of health (SDOH) are associated with TBI incidence among older adults.

Design, Setting, and Participants

This nationally representative longitudinal cohort study assessed participants for 18 years, from August 2000 through December 2018, using data from the Health and Retirement Study (HRS) and linked Medicare claims dates. Analyses were completed August 9 through December 12, 2022. Participants were 65 years of age or older in the HRS with survey data linked to Medicare without a TBI prior to HRS enrollment. They were community dwelling at enrollment but were retained in HRS if they were later institutionalized.

Exposures

Baseline demographic, cognitive, medical, and SDOH information from HRS.

Main Outcomes and Measures

Incident TBI was defined using inpatient and outpatient International Classification of Diseases, Ninth or Tenth Revision, diagnosis codes received the same day or within 1 day as the emergency department (ED) visit code and the computed tomography (CT) or magnetic resonance imaging (MRI) code, after baseline HRS interview. A cohort with TBI codes but no ED visit or CT or MRI scan was derived to capture diagnoses in nonhospital settings. Descriptive statistics and bivariate associations of TBI with demographic and SDOH characteristics used sample weights. Fine-Gray regression models estimated associations between covariates and TBI, with death as a competing risk. Imputation considering outcome and complex survey design was performed by race and ethnicity, sex, education level, and Area Deprivation Index percentiles 1, 50, and 100. Other exposure variables were fixed at their weighted means.

Results

Among 9239 eligible respondents, 5258 (57.7%) were female and 1210 (9.1%) were Black, 574 (4.7%) were Hispanic, and 7297 (84.4%) were White. Mean (SD) baseline age was 75.2 (8.0) years. During follow-up (18 years), 797 (8.9%) of respondents received an incident TBI diagnosis with an ED visit and a CT code within 1 day, 964 (10.2%) received an incident TBI diagnosis and an ED code, and 1148 (12.9%) received a TBI code with or without an ED visit and CT scan code. Compared with respondents without incident TBI, respondents with TBI were more likely to be female (absolute difference, 7.0 [95% CI, 3.3-10.8]; P < .001) and White (absolute difference, 5.1 [95% CI, 2.8-7.4]; P < .001), have normal cognition (vs cognitive impairment or dementia; absolute difference, 6.1 [95% CI, 2.8-9.3]; P = .001), higher education (absolute difference, 3.8 [95% CI, 0.9-6.7]; P < .001), and wealth (absolute difference, 6.5 [95% CI, 2.3-10.7]; P = .01), and be without baseline lung disease (absolute difference, 5.1 [95% CI, 3.0-7.2]; P < .001) or functional impairment (absolute difference, 3.3 [95% CI, 0.4-6.1]; P = .03). In adjusted multivariate models, lower education (subdistribution hazard ratio [SHR], 0.73 [95% CI, 0.57-0.94]; P = .01), Black race (SHR, 0.61 [95% CI, 0.46-0.80]; P < .001), area deprivation index national rank (SHR 1.00 [95% CI 0.99-1.00]; P = .009), and male sex (SHR, 0.73 [95% CI, 0.56-0.94]; P = .02) were associated with membership in the group without TBI. Sensitivity analyses using a broader definition of TBI yielded similar results.

Conclusions and Relevance

In this longitudinal cohort study of older adults, almost 13% experienced incident TBI during the 18-year study period. For older adults who seek care for TBI, race and ethnicity, sex, and SDOH factors may be associated with incidence of TBI, seeking medical attention for TBI in older adulthood, or both.

Traumatic brain injury and occupational risk of low-level blast exposure on adverse career outcomes: an examination of administrative and medical separations from Service (2005-2015)

Introduction

Although traumatic brain injury (TBI) has been linked with adverse long-term health, less research has examined whether TBI is linked with non-clinical outcomes including involuntary job loss. Symptoms associated with TBI may influence one's ability to maintain gainful employment including employment in the U.S. military. That influence may impact military service members with exposure to repetitive low-level blast (LLB). Understanding the association between TBI and involuntary job loss outcomes among military populations is particularly important as it may be associated with differences in eligibility for post-service benefits. The purpose of the present research was to determine whether (1) TBI and related conditions are associated with involuntary job loss (i.e., medical and administrative separations from service) among military personnel, and (2) occupational risk of LLB is associated with involuntary job loss in both the presence and absence of clinical diagnoses of TBI and related conditions.

Method

This research leveraged population-level data from the Career History Archival Medical and Personnel System for enlisted personnel who served on active duty between 2005-2015. Risk of LLB exposure was categorized using military occupational specialty as a proxy. Medical diagnoses were identified using ICD-9 codes. Separations for medical and administrative reasons were identified.

Results

Risk for administrative separation differed across medical diagnoses of interest, but those who worked in high-risk occupations were more likely to be administratively separated than those working in low-risk occupations. Risk for medical separation was associated with occupational risk of LLB and each of the diagnoses of interest, though significant interactions suggested that the effects of certain diagnoses of interest (e.g., concussion, cognitive problems, postconcussive syndrome, migraines) on medical separations was greater among those working in high-risk occupations.

Discussion

Taken together, the present research suggests that TBI and associated medical conditions, as well as occupational risk of LLB, are associated with long-term involuntary job loss for medical reasons. This study is the first to demonstrate involuntary military job loss outcomes associated with TBI, mental health conditions, and conditions associated with blast exposure using both inpatient and outpatient population-level data and may have important implications for civilian employment and post-service benefits.

Longitudinal Functional Connectome in Pediatric Concussion: An Advancing Concussion Assessment in Pediatrics Study

Advanced magnetic resonance imaging (MRI) techniques indicate that concussion (i.e., mild traumatic brain injury) disrupts brain structure and function in children. However, the functional connectivity of brain regions within global and local networks (i.e., functional connectome) is poorly understood in pediatric concussion. This prospective, longitudinal study addressed this gap using data from the largest neuroimaging study of pediatric concussion to date to study the functional connectome longitudinally after concussion as compared with mild orthopedic injury (OI). Children and adolescents (n = 967) 8-16.99 years with concussion or mild OI were recruited from pediatric emergency departments within 48 h post-injury. Pre-injury and 1-month post-injury symptom ratings were used to classify concussion with or without persistent symptoms based on reliable change. Subjects completed a post-acute (2-33 days) and chronic (3 or 6 months via random assignment) MRI scan. Graph theory metrics were derived from 918 resting-state functional MRI scans in 585 children (386 concussion/199 OI). Linear mixed-effects modeling was performed to assess group differences over time, correcting for multiple comparisons. Relative to OI, the global clustering coefficient was reduced at 3 months post-injury in older children with concussion and in females with concussion and persistent symptoms. Time post-injury and sex moderated group differences in local (regional) network metrics of several brain regions, including degree centrality, efficiency, and clustering coefficient of the angular gyrus, calcarine fissure, cuneus, and inferior occipital, lingual, middle occipital, post-central, and superior occipital gyrus. Relative to OI, degree centrality and nodal efficiency were reduced post-acutely, and nodal efficiency and clustering coefficient were reduced chronically after concussion (i.e., at 3 and 6 months post-injury in females; at 6 months post-injury in males). Functional network alterations were more robust and widespread chronically as opposed to post-acutely after concussion, and varied by sex, age, and symptom recovery at 1-month post-injury. Local network segregation reductions emerged globally (across the whole brain network) in older children and in females with poor recovery chronically after concussion. Reduced functioning between neighboring regions could negatively disrupt specialized information processing. Local network metric alterations were demonstrated in several posterior regions that are involved in vision and attention after concussion relative to OI. This indicates that functioning of superior parietal and occipital regions could be particularly susceptibile to the effects of concussion. Moreover, those regional alterations were especially apparent at later time periods post-injury, emerging after post-concussive symptoms resolved in most and persisted up to 6 months post-injury, and differed by biological sex. This indicates that neurobiological changes continue to occur up to 6 months after pediatric concussion, although changes emerge earlier in females than in males. Changes could reflect neural compensation mechanisms.

Lifetime Traumatic Brain Injury and Risk of Post-Concussive Symptoms in the Millennium Cohort Study

Traumatic brain injury (TBI) is prevalent among active duty military service members, with studies reporting up to 23% experiencing at least one TBI, with 10-60% of service members reporting at least one subsequent repeat TBI. A TBI has been associated with an increased risk of cumulative effects and long-term neurobehavioral symptoms, impacting operational readiness in the short-term and overall health in the long term. The association between multiple TBI and post-concussive symptoms (PCS), however, defined as symptoms that follow a concussion or TBI, in the military has not been adequately examined. Previous studies in military populations are limited by methodological issues including small sample sizes, the use of non-probability sampling, or failure to include the total number of TBI. To overcome these limitations, we examined the association between the total lifetime number of TBI and total number of PCS among U.S. active duty military service members who participated in the Millennium Cohort Study. A secondary data analysis was conducted using the Millennium Cohort Study's 2014 survey (n = 28,263) responses on self-reported TBI and PCS (e.g., fatigue, restlessness, sleep disturbances, poor concentration, or memory loss). Zero-inflated negative binomial models calculated prevalence ratios (PRs) and 95% confidence intervals (CIs) for the unadjusted and adjusted associations between lifetime TBIs and PCS. A third of military participants reported experiencing one or more TBIs during their lifetime with 72% reporting at least one PCS. As the mean number of PCS increased, mean lifetime TBIs increased. The mean number of PCS by those with four or more TBI (4.63) was more than twice that of those with no lifetime TBI (2.28). One, two, three, and four or more TBI had 1.10 (95% CI: 1.06-1.15), 1.19 (95% CI: 1.14-1.25), 1.23 (95% CI: 1.17-1.30), and 1.30 times (95% CI: 1.24-1.37) higher prevalence of PCS, respectively. The prevalence of PCS was 2.4 (95% CI: 2.32-2.48) times higher in those with post-traumatic stress disorder than their counterparts. Active duty military service members with a history of TBI are more likely to have PCS than those with no history of TBI. These results suggest an elevated prevalence of PCS as the number of TBI increased. This highlights the need for robust, longitudinal studies that can establish a temporal relationship between repetitive TBI and incidence of PCS. These findings have practical relevance for designing both workplace safety prevention measures and treatment options regarding the effect on and from TBI among military personnel.

Differences in Risk of Alzheimer's Disease Following Later-Life Traumatic Brain Injury in Veteran and Civilian Populations

OBJECTIVE

To directly compare the effect of incident age 68+ traumatic brain injury (TBI) on the risk of diagnosis of clinical Alzheimer's disease (AD) in the general population of older adults, and between male veterans and nonveterans; to assess how this effect changes with time since TBI.

SETTING AND PARTICIPANTS

Community-dwelling traditional Medicare beneficiaries 68 years or older from the Health and Retirement Study (HRS).

DESIGN

Fine-Gray models combined with inverse-probability weighting were used to identify associations between incident TBI, post-TBI duration, and TBI treatment intensity, with a diagnosis of clinical AD dementia. The study included 16 829 older adults followed over the 1991-2015 period. For analyses of veteran-specific risks, 4281 veteran males and 3093 nonveteran males were identified. Analysis of veteran females was unfeasible due to the age structure of the population. Information on occurrence(s) of TBI, and onset of AD and risk-related comorbidities was constructed from individual-level HRS-linked Medicare claim records while demographic and socioeconomic risk factors were based on the survey data.

RESULTS

Later-life TBI was strongly associated with increased clinical AD risk in the full sample (pseudo-hazard ratio [HR]: 3.22; 95% confidence interval [CI]: 2.57-4.05) and in veteran/nonveteran males (HR: 5.31; CI: 3.42-7.94), especially those requiring high-intensity/duration care (HR: 1.58; CI: 1.29-1.91). Effect magnitude decreased with time following TBI (HR: 0.72: CI: 0.68-0.80).

CONCLUSION

Later-life TBI was strongly associated with increased AD risk, especially in those requiring high-intensity/duration care. Effect magnitude decreased with time following TBI. Univariate analysis showed no differences in AD risk between veterans and nonveterans, while the protective effect associated with veteran status in Fine-Gray models was largely due to differences in demographics, socioeconomics, and morbidity. Future longitudinal studies incorporating diagnostic procedures and documentation quantifying lifetime TBI events are necessary to uncover pathophysiological mediating and/or moderating mechanisms between TBI and AD.

Effect of Voluntary Exercise on Endogenous Pain Control Systems and Post-traumatic Headache in Mice

Traumatic brain injury (TBI) can cause acute and chronic pain along with motor, cognitive, and emotional problems. Although the mechanisms are poorly understood, previous studies suggest disruptions in endogenous pain modulation may be involved. Voluntary exercise after a TBI has been shown to reduce some consequences of injury including cognitive impairment. We hypothesized, therefore, that voluntary exercise could augment endogenous pain control systems in a rodent model of TBI. For these studies, we used a closed-head impact procedure in male mice modeling mild TBI. We investigated the effect of voluntary exercise on TBI-induced hindpaw nociceptive sensitization, diffuse noxious inhibitory control failure, and periorbital sensitization after bright light stress, a model of post-traumatic headache. Furthermore, we investigated the effects of exercise on memory, circulating markers of brain injury, neuroinflammation, and spinal cord gene expression. We observed that exercise significantly reduced TBI-induced hindpaw allodynia and periorbital allodynia in the first week following TBI. We also showed that exercise improved the deficits associated with diffuse noxious inhibitory control and reduced bright light stress-induced allodynia up to 2 months after TBI. In addition, exercise preserved memory and reduced TBI-induced increases in spinal BDNF, CXCL1, CXCL2, and prodynorphin expression, all genes previously linked to TBI-induced nociceptive sensitization. Taken together, our observations suggest that voluntary exercise may reduce pain after TBI by reducing TBI-induced changes in nociceptive signaling and preserving endogenous pain control systems. PERSPECTIVE: This article evaluates the effects of exercise on pain-related behaviors in a preclinical model of traumatic brain injury (TBI). The findings show that exercise reduces nociceptive sensitization, loss of diffuse noxious inhibitory control, memory deficits, and spinal nociception-related gene expression after TBI. Exercise may reduce or prevent pain after TBI.

Neuroprotective Effect of Sub-lethal Hyperthermia Preconditioning in a Rat Model of Repeated Closed Head Injury

Repeated mild traumatic brain injury (rTBI), one of the most common forms of traumatic brain injury, is a worldwide severe public health concern. rTBI induces cumulative neuronal injury, neurological dysfunction, and cognitive deficits. Although there are clinical treatment methods, there is still an urgent need to develop preventive approaches for susceptible populations. Using a repeated closed head injury (rCHI) rat model, we interrogate the effect of sub-lethal hyperthermia preconditioning (SHP) on rCHI-induced neuronal injury and behavioral changes. Our study applied the repeated weight-drop model to induce the rCHI. According to the changes of heat shock protein 70 (HSP 70) in the cortex and hippocampus following a single SHP treatment in normal rats, the SHP was delivered to the rats 18 hours before rCHI. We found that HSP significantly alleviated rCHI-induced anxiety-like behaviors and impairments in motor abilities and spatial memory. SHP exerts significant neuroprotection against rCHI-induced neuronal damage, apoptosis, and neuroinflammation. Our findings support the potential use of SHP as a preventative approach for alleviating rCHI-induced brain damage.

Clinical Updates in Mild Traumatic Brain Injury (Concussion)

Traumatic brain injury (TBI) affects > 3 million people in the United States annually. Although the number of deaths related to severe TBIs has stabalized, mild TBIs, often termed concussions, are increasing. As evidence indicates that a significant proportion of these mild injuries are associated with long-lasting functional deficits that impact work performance, social integration, and may predispose to later cognitive decline, it is important that we (a) recognize these injuries, (b) identify those at highest risk of poor recovery, and (c) initiate appropriate treatments promptly. We discuss the epidemiology of TBI, the most common persistent symptoms, and treatment approaches.

Traumatic Brain Injury History Among Individuals Using Mental Health and Addictions Services: A Scoping Review

OBJECTIVE

Traumatic brain injury (TBI) has been increasingly linked in population research to psychiatric problems as well as substance use and related harms, suggesting that individuals with TBI may also present more frequently to mental health and addictions (MHA) services. Little is known, however, about TBI history among MHA service users. The objectives of this review were to understand (i) the prevalence of TBI history among MHA service users; (ii) how TBI history is identified in MHA service settings; and (iii) predictors or outcomes of TBI that have been reported in MHA service users.

METHODS

A scoping review was conducted in accordance with PRISMA Scoping Review Extension guidelines. A search for relevant literature was conducted in MEDLINE, PsycINFO, SPORTDiscus, CINAHL, and Embase as well as various gray literature sources.

RESULTS

Twenty-eight relevant studies were identified. TBI was defined and operationalized heterogeneously between studies, and TBI history prevalence rates ranged considerably among the study samples. The included studies used varied methods to identify TBI history in MHA settings, such as clinical chart audits, single-item questions, or structured questionnaires (eg, Brain Injury Screening Questionnaire or Ohio State University TBI Identification Method). TBI history was most consistently associated with indicators of more severe substance use problems and mental health symptoms as well as increased aggression or risk to others. Studies reported less consistent findings regarding the relationship of TBI to physical health, cognitive impairment, functioning, risk to self, and type of psychiatric diagnosis.

CONCLUSION

Screening for TBI history in MHA settings may contribute important information for risk assessment and care planning. However, to be clinically useful, assessment of TBI history will require consistent operationalization of TBI as well as use of validated screening methods.

Concussion Evaluation Patterns Among US Adults

OBJECTIVE

The objective of this study was to compare individuals who were not evaluated by a doctor or nurse for a self-reported concussion versus individuals who were evaluated for a concussion by demographic variables, concussion history, and concussion circumstances.

SETTINGS AND PARTICIPANTS

Data were collected from 2018 SpringStyles, a web-based panel survey of US adults 18 years or older ( n = 6427), fielded in March-April.

DESIGN

Cross-sectional.

MAIN MEASURES

Respondents were asked whether they believed they had sustained a concussion in their lifetime and details about their most recent concussion, including whether they were evaluated by a doctor or nurse.

RESULTS

Twenty-seven percent of adults in the survey reported a lifetime concussion ( n = 1835). Among those individuals, 50.4% were not evaluated by a healthcare provider for their most recent concussion. Not being evaluated was higher among individuals whose concussion was caused by a slip, trip, or fall (adjusted prevalence ratio [APR] = 2.22; 95% CI, 1.65-2.99), riding a bicycle (APR = 2.28; 95% CI, 1.58-3.27), being struck by or against something by accident (APR = 2.50; 95% CI, 1.88-3.34), or being struck by or against something during a fight or argument (APR = 2.89; 95% CI, 2.11-3.97), compared with individuals whose concussion was caused by a motor vehicle crash. No evaluation was also higher among individuals whose concussion occurred while engaging in a sports or recreational activity (APR = 1.39; 95% CI, 1.07-1.82) or engaging in regular activities around the house (APR = 1.65; 95% CI, 1.27-2.14), compared with individuals whose concussion occurred while working for pay.

CONCLUSION

More than a quarter of adults reported a lifetime concussion; however, half of them were not evaluated for their last concussion by a healthcare provider. Examination by a healthcare professional for a suspected concussion may prevent or mitigate potential long-term sequelae. Furthermore, current US surveillance methods may underestimate the burden of TBI because many individuals do not seek evaluation.

Prophylactic treatment with CN-105 improves functional outcomes in a murine model of closed head injury

The treatment of traumatic brain injury (TBI) in military populations is hindered by underreporting and underdiagnosis. Clinical symptoms and outcomes may be mitigated with an effective pre-injury prophylaxis. This study evaluates whether CN-105, a 5-amino acid apolipoprotein E (ApoE) mimetic peptide previously shown to modify the post-traumatic neuroinflammatory response, would maintain its neuroprotective effects if administered prior to closed-head injury in a clinically relevant murine model. CN-105 was synthesized by Polypeptide Inc. (San Diego, CA) and administered to C57-BL/6 mice intravenously (IV) and/or by intraperitoneal (IP) injection at various time points prior to injury while vehicle treated animals received IV and/or IP normal saline. Animals were randomized following injury and behavioral observations were conducted by investigators blinded to treatment. Vestibulomotor function was assessed using an automated Rotarod (Ugo Basile, Comerio, Italy), and hippocampal microglial activation was assessed using F4/80 immunohistochemical staining in treated and untreated mice 7 days post-TBI. Separate, in vivo assessments of the pharmacokinetics was performed in healthy CD-1. IV CN-105 administered prior to head injury improved vestibulomotor function compared to vehicle control-treated animals. CN-105 co-administered by IP and IV dosing 6 h prior to injury also improved vestibulomotor function up to 28 days following injury. Microglia counted in CN-105 treated specimens were significantly fewer (P = 0.03) than in vehicle specimens. CN-105 improves functional outcomes and reduces hippocampal microglial activation when administered prior to injury and could be adapted as a pre-injury prophylaxis for soldiers at high risk for TBI.

Healthcare choices following mild traumatic brain injury in Australia

BACKGROUND

Accurate data on the types of healthcare people seek in the early stages following mild traumatic brain injury (mTBI) in Australia is lacking. We sought to investigate the types of healthcare people seek following mTBI, including seeking no care at all; ascertain the demographic, pre- and peri-injury factors, and symptom characteristics associated with the care that people access; and examine whether choice of care is associated with symptomatic recovery and quality of life.

METHODS

An online retrospective survey of Australians aged 18 to 65 years who had experienced a self-reported 'concussion' (mTBI) within the previous 18 months. Types of healthcare accessed were investigated, as well as those who did not seek any care. Data were analysed using frequency and percentages, chi-squared tests and logistic regression models.

RESULTS

A total of 201 respondents had experienced a self-reported 'concussion' but 21.4% of the respondents did not seek any care. Of the 183 respondents who sought healthcare, 52.5% attended a hospital Emergency Department, 41.0% attended a general practitioner and 6.6% accessed sports-based care. Compared to their counterparts, those who had a lower level of education (p = 0.001), had experienced previous mTBI (p = 0.045) or previous mental health issues (p = 0.009) were less likely to seek healthcare, whilst those who had experienced loss of consciousness (p = 0.014), anterograde (p = 0.044) or retrograde (p = 0.009) amnesia, and symptoms including drowsiness (p = 0.005), nausea (p = 0.040), and feeling slow (p = 0.031) were more likely to seek care. Those who did not seek care were more likely to recover within one month (AOR 4.90, 95%CI 1.51 - 15.89, p = 0.008), albeit the relatively large 95%CI warrants careful interpretation. Compared to seeking care, not seeking care was not found to be significantly associated with symptom resolution nor quality of life (p > 0.05).

CONCLUSIONS

This study provides unique insight into factors associated with healthcare utilisation in the early stages following mTBI, as well as outcomes associated with choice of care, including not seeking care. Delivering targeted community education on the signs and symptoms of mTBI, and the advantages of seeking care following injury is an important step forward in the management of this challenging condition.

AUS-TBI: The Australian Health Informatics Approach to Predict Outcomes and Monitor Intervention Efficacy after Moderate-to-Severe Traumatic Brain Injury

Predicting and optimizing outcomes after traumatic brain injury (TBI) remains a major challenge because of the breadth of injury characteristics and complexity of brain responses. AUS-TBI is a new Australian Government–funded initiative that aims to improve personalized care and treatment for children and adults who have sustained a TBI. The AUS-TBI team aims to address a number of key knowledge gaps, by designing an approach to bring together data describing psychosocial modulators, social determinants, clinical parameters, imaging data, biomarker profiles, and rehabilitation outcomes in order to assess the influence that they have on long-term outcome. Data management systems will be designed to track a broad range of suitable potential indicators and outcomes, which will be organized to facilitate secure data collection, linkage, storage, curation, management, and analysis. It is believed that these objectives are achievable because of our consortium of highly committed national and international leaders, expert committees, and partner organizations in TBI and health informatics. It is anticipated that the resulting large-scale data resource will facilitate personalization, prediction, and improvement of outcomes post-TBI.

Relation of Mild Traumatic Brain Injury history to abnormalities on a preliminary Neuroendocrine screen; A multicenter LIMBIC-CENC analysis

PRIMARY OBJECTIVES

Determine if an abnormal preliminary neuroendocrine disorder (NED) blood test screen is associated with mild TBI (mTBI) history or post-concussiveclinical features.

RESEARCH DESIGN

Observational.

METHODS

Among 1,520 participants with military combatexposure, we measured randomly timed serum levels of insulin-likegrowth factor-1, thyroid stimulating hormone (TSH), and total testosterone as a preliminary NED screen. Using multivariable models, we analyzed relation of screen results in mTBI group membership and post-concussiveclinical features (fatigue, depression, cognitive symptoms, executive function, processing speed).

RESULTS

None of the mTBI positive groups, including repetitive (≥3 mTBI) and blast-related,differed from the non-TBIcontrols on rates of abnormal lab screen or rates of growth hormone deficiency (GHD), hypothyroidism or male hypogonadism in treatment records. Lab screen findings were also not associated with any clinical feature.

CONCLUSIONS

This study shows no evidence that remote mTBI(s) or implicated post-concussiveclinical features are linked to GHD, hypothyroidism or male hypogonadism. Large case-controlstudies incorporating more definitive neuroendocrine disorder NED testing (TSH plus thyroxine, early morning testosterone, LH, FSH, prolactin and GH provocative testing) are needed to determine whether mTBI(s) alone elevate one's risk for chronic NED and how best to select patients for comprehensive testing.

Canadians Reporting Sport-Related Concussions: Increasing and Now Stabilizing

BACKGROUND

Canada is currently engaged in a national harmonization of strategies to prevent and manage sport-related concussions.

OBJECTIVE

To examine the annual incidence rates of reported sport-related concussions or other brain injuries by participants in the Canadian Community Health Survey, a national public health survey which provides nearly 2 decades of serial data using consistent methodology.

DESIGN

Serial cross-sectional survey.

SETTING

Population-based Canadian survey from 2000 to 2018 that collects data on "concussions or other brain injuries."

PARTICIPANTS

Respondents 12 years and older.

INDEPENDENT VARIABLES

Sex and age categorized 12 to 14 years, 15 to 19 years, 20 to 29 years, and 30+ years.

OUTCOME MEASURES

National incidence rates of participants reporting concussions or other brain injuries occurring within the previous year while engaged in "organized sports/leisure sports or physical exercise."

RESULTS

Data were available for 2000/01, 2003, 2005/6, 2009/10, 2013/4, and 2017/8 (N = 757 383). A previously stable annual incidence of reported sport-related concussions or other brain injuries increased nearly 2 and a half-fold from 2005/06 through 2013/14 (P < 0.0001) but seems to have stabilized recently (2013/14 vs 2017/8, P = 0.35). This trend is similar for both men and women but is manifest primarily within youth (12-19 years) as opposed to adults (>19 years). Approximately 1 in 450 Canadians 12 years and older report sport-related concussions or other brain injuries as their most significant injury associated with disability in the previous year (2017-2018: 221 per 100 000 population, 95% confidence interval: 179-264).

CONCLUSIONS

In Canada, the annual incidence rates of reported sport-related concussions or other brain injuries is changing and may reflect improved reporting and recognition.

Mild Traumatic Brain Injuries and Future Risk of Developing Alzheimer’s Disease: Systematic Review and Meta-Analysis

Background: Traumatic brain injury (TBI) increases the risk of future dementia and Alzheimer’s disease (AD). However, it is unclear whether this is true for mild TBI (mTBI). Objective: To explore the association between mTBI and subsequent risk of developing AD. Method: We systematically searched four electronic databases from January 1954 to April 2020. We included studies reporting primary data and where mTBI preceded AD by≥5 years. We meta-analyzed included studies for both high quality studies and studies with a follow up of > 10 years. Result: We included 5 of the 10,435 results found. Meta-analysis found a history of mTBI increased risk of AD (pooled relative risk = 1.18, 95% CI 1.11–1.25, N = 3,149,740). The sensitivity analysis including only studies in which mTBI preceded AD by > 10 years, excluded two very large studies and resulted in wider confidence intervals (RR = 2.02, 95% CI 0.66–6.21, N = 2307). Conclusion: There is an increased risk of AD following mTBI. Our findings of increased risk even with mTBI means it cannot be assumed that mild head injuries from sports are harmless. The sensitivity analysis suggests that we cannot exclude reverse causation, and longer follow up times are needed. Implementation of policy to reduce mTBIs, including in children and sportsmen, are urgently needed. Further research is needed on the effect of frequency and age at injury of mTBIs.

Association of Traumatic Brain Injury With the Risk of Developing Chronic Cardiovascular, Endocrine, Neurological, and Psychiatric Disorders

IMPORTANCE

Increased risk of neurological and psychiatric conditions after traumatic brain injury (TBI) is well-defined. However, cardiovascular and endocrine comorbidity risk after TBI in individuals without these comorbidities and associations with post-TBI mortality have received little attention.

OBJECTIVE

To assess the incidence of cardiovascular, endocrine, neurological, and psychiatric comorbidities in patients with mild TBI (mTBI) or moderate to severe TBI (msTBI) and analyze associations between post-TBI comorbidities and mortality.

DESIGN, SETTING, AND PARTICIPANTS

This prospective longitudinal cohort study used hospital-based patient registry data from a tertiary academic medical center to select patients without any prior clinical comorbidities who experienced TBI from 2000 to 2015. Using the same data registry, individuals without head injuries, the unexposed group, and without target comorbidities were selected and age-, sex-, and race-frequency-matched to TBI subgroups. Patients were followed-up for up to 10 years. Data were analyzed in 2021.

EXPOSURES

Mild or moderate to severe head trauma.

MAIN OUTCOMES AND MEASURES

Cardiovascular, endocrine, neurologic, and psychiatric conditions were defined based on International Classification of Diseases, Ninth Revision (ICD-9) or International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10). Associations between TBI and comorbidities, as well as associations between the comorbidities and mortality, were analyzed.

RESULTS

A total of 4351 patients with mTBI (median [IQR] age, 45 [29-57] years), 4351 patients with msTBI (median [IQR] age, 47 [30-58] years), and 4351 unexposed individuals (median [IQR] age, 46 [30-58] years) were included in analyses. In each group, 45% of participants were women. mTBI and msTBI were significantly associated with higher risks of cardiovascular, endocrine, neurologic, and psychiatric disorders compared with unexposed individuals. In particular, hypertension risk was increased in both mTBI (HR, 2.5; 95% CI, 2.1-2.9) and msTBI (HR, 2.4; 95% CI, 2.0-2.9) groups. Diabetes risk was increased in both mTBI (HR, 1.9; 95% CI, 1.4-2.7) and msTBI (HR, 1.9; 95% CI, 1.4-2.6) groups, and risk of ischemic stroke or transient ischemic attack was also increased in mTBI (HR, 2.2; 95% CI, 1.4-3.3) and msTBI (HR, 3.6; 95% CI, 2.4-5.3) groups. All comorbidities in the TBI subgroups emerged within a median (IQR) of 3.49 (1.76-5.96) years after injury. Risks for post-TBI comorbidities were also higher in patients aged 18 to 40 years compared with age-matched unexposed individuals: hypertension risk was increased in the mTBI (HR, 5.9; 95% CI, 3.9-9.1) and msTBI (HR, 3.9; 95% CI, 2.5-6.1) groups, while hyperlipidemia (HR, 2.3; 95% CI, 1.5-3.4) and diabetes (HR, 4.6; 95% CI, 2.1-9.9) were increased in the mTBI group. Individuals with msTBI, compared with unexposed patients, had higher risk of mortality (432 deaths [9.9%] vs 250 deaths [5.7%]; P < .001); postinjury hypertension (HR, 1.3; 95% CI, 1.1-1.7), coronary artery disease (HR, 2.2; 95% CI, 1.6-3.0), and adrenal insufficiency (HR, 6.2; 95% CI, 2.8-13.0) were also associated with higher mortality.

CONCLUSIONS AND RELEVANCE

These findings suggest that TBI of any severity was associated with a higher risk of chronic cardiovascular, endocrine, and neurological comorbidities in patients without baseline diagnoses. Medical comorbidities were observed in relatively young patients with TBI. Comorbidities occurring after TBI were associated with higher mortality. These findings suggest the need for a targeted screening program for multisystem diseases after TBI, particularly chronic cardiometabolic diseases.

Factors that Influence Follow-Up Care for Families of Children with Acquired Brain Injury: A Scoping Review

PURPOSE

To describe factors that contribute to medical/rehabilitation service access following pediatric acquired brain injury (ABI) and identify gaps in the literature to guide future research.

MATERIALS & METHODS

The PRISMA framework for scoping reviews guided this process. Peer-reviewed journal databases were searched for articles published between 1/2008 and 12/2020, identifying 400 unique articles. For full inclusion, articles had to examine a variable related to the receipt or initiation of medical/rehabilitative services for children with ABI. Review articles and non-English articles were excluded.

RESULTS

Nine studies met full inclusion criteria. Included studies identified factors focused on four primary areas: understanding brain injury education/recommendations and ease of implementing recommendations, ease of scheduling and attending appointments, age/injury factors, and sociocultural factors. Well-scheduled appointments and simple strategies facilitated families' access to care and implementation of recommendations. An overwhelming number of recommendations, socioeconomic variables, and transportation challenges served as barriers for families and schools.

CONCLUSIONS

This scoping review offers several directions on which researchers can build to improve access to care and recommendation-implementation for families who have a child with an ABI. Enhanced understanding of these factors may lead to better service access, reduction of unmet needs, and enhanced long-term outcomes for children with ABI.

Neuropsychological and neuropsychiatric recovery from mild traumatic brain injury

PURPOSE OF REVIEW

Mild traumatic brain injury (mTBI) is a significant public health concern for children. This review summarizes recent literature on early symptoms and neuropsychiatric and neuropsychological outcomes following pediatric mTBI and highlights factors that predict prolonged recovery. Evidence-based recommendations for assessment and treatment are also discussed.

RECENT FINDINGS

Whereas most children recover within 1 month after mTBI, 10-30% of children experience lingering neuropsychiatric or neuropsychological symptoms 3 months or more after injury. For the subset who experience prolonged recovery, new or worsening emotional and behavioral symptoms are the most frequent concerns. Recent research has suggested that specific factors, including preinjury mental health concerns, female sex, and family characteristics, are associated with increased risk of experiencing prolonged recovery. Early management includes reassurance, brief rest (1-3 days), and gradual return to typical activities. When symptoms linger for more than 4 weeks, evaluation in a specialty clinic is recommended and multimodal therapies are considered. Active recovery models, which include gradual return to aerobic exercise and cognitive behavioral approaches, are promising for the management of prolonged symptoms.

SUMMARY

A minority of children with mTBI experience prolonged neuropsychiatric or neuropsychological concerns. While our understanding of pediatric mTBI is growing, and recommendations for assessment and management have been developed, many gaps remain.

Characterizing Traumatic Brain Injury and Its Association with Losing Stable Housing in a Community-based Sample

OBJECTIVE

Traumatic brain injury (TBI) is increasingly recognized as a common and impactful health determinant in homeless and precariously housed populations. We sought to describe the history of TBI in a precariously housed sample and evaluate how TBI was associated with the initial loss and lifetime duration of homelessness and precarious housing.

METHOD

We characterized the prevalence, mechanisms, and sex difference of lifetime TBI in a precariously housed sample. We also examined the impact of TBI severity and timing on becoming and staying homeless or precariously housed; 285 precariously housed participants completed the Brain Injury Screening Questionnaire in addition to other health assessments.

RESULTS

A history of TBI was reported in 82.1% of the sample, with 64.6% reporting > 1 TBI, and 21.4% reporting a moderate or severe TBI. Assault was the most common mechanism of injury overall, and females reported significantly more traumatic brain injuries due to physical abuse than males (adjusted OR = 1.26, 95% CI = 1.14 to 1.39, P < 0.0001). The first moderate or severe TBI was significantly closer to the first experience of homelessness (b = 2.79, P = 0.003) and precarious housing (b = 2.69, P < 0.0001) than was the first mild TBI. In participants who received their first TBI prior to becoming homeless or precariously housed, traumatic brain injuries more proximal to the initial loss of stable housing were associated with a longer lifetime duration of homelessness (RR = 1.04, 95% CI = 1.02 to 1.06, P < 0.0001) and precarious housing (RR = 1.03, 95% CI = 1.01 to 1.04, P < 0.0001).

CONCLUSIONS

These findings demonstrate the high prevalence of TBI in this vulnerable population, and that aspects of TBI severity and timing are associated with the loss and lifetime duration of stable housing.

The impact of mild traumatic brain injury on reading comprehension and eye movements: preliminary results

INTRODUCTION

Individuals who sustain a mild traumatic brain injury (mTBI) can suffer from executive function, working memory, and attention deficits, which can impact functional task performance, including reading comprehension. Individuals with mTBI commonly report reading difficulties, but such difficulties have been historically difficult to capture using behavioral measures. The current study examined reading performance in those with and without mTBI using eye-tracking measures, which may be more sensitive to reading impairment in mTBI.

METHOD/RESULTS

In Experiment 1, 26 participants with a history of mTBI and 26 healthy control participants completed working memory (WM) and reading comprehension tasks. We found no differences in behavioral measures but found that spontaneous eye-blinking frequency was lower during the reading task in the mTBI group. In Experiment 2, we explored the impact of auditory distraction (e.g., multi-talker babble) on reading and memory performance. Twenty-three new participants with a history of mTBI and 26 healthy control participants completed a short-term memory (STM) task, a WM task, and a reading comprehension task under two distraction conditions. As in Experiment 1, we found no differences on behavioral measures, but observed significant differences on spontaneous eye-blinking frequency between those with and without mTBI. Group differences in distraction effects were also observed and performance on the WM task predicted reading comprehension performance.

CONCLUSIONS

The lack of differences on behavioral measures between groups, but lower frequencies of spontaneous eye blinking in the mTBI group suggests that while these individuals successfully completed the reading comprehension task, they may require more cognitive resources to do so.

Neural Correlates of Traumatic Brain Injury in Women Survivors of Intimate Partner Violence: A Structural and Functional Connectivity Neuroimaging Study

OBJECTIVE

More than one-third of women in the United States experience intimate partner violence (IPV) in their lifetime, increasing their risk for traumatic brain injury (TBI). Despite the prevalence of TBI among IPV survivors, research is sparse in comparison with parallel populations (eg, military, accidents, sports). This pilot study aimed to provide a preliminary investigation of the effect of TBI on brain morphometry and resting-state functional connectivity in women who experience IPV.

PARTICIPANTS

A total of 45 community-dwelling women survivors of IPV who screened positive for posttraumatic stress disorder (PTSD).

DESIGN

Participants completed comprehensive assessments of trauma exposure, PTSD, TBI history, and brain neurological health. Twenty-three participants (51.1%) met diagnostic criteria for lifetime TBI. Of these, 15 participants experienced 1 or more TBIs resulting from IPV. The remaining participants experienced TBI from non-IPV exposures (eg, sports/motor vehicle accident). Surface-based neuroimaging analyses were performed to examine group differences in cortical thickness and in functional connectivity of amygdala and isthmus cingulate seeds to examine emotion regulation and the default mode network, respectively.

MAIN MEASURES

Boston Assessment of Traumatic Brain Injury-Lifetime for Intimate Partner Violence (BAT-L/IPV); Clinician Administered PTSD Scale (CAPS); structural and functional neuroimaging.

RESULTS

History of lifetime TBI in women IPV survivors was associated with differences in cortical thickness as well as functional connectivity between the isthmus cingulate seed and a variety of regions, including superior parietal and frontal cortices. Individuals with IPV-related TBI showed lower cortical thickness in the right paracentral gyrus than individuals with TBI from other non-IPV etiologies.

CONCLUSION

Significant differences in brain structure and connectivity were observed in individuals with IPV and TBI. A lower mean cortical thickness of the paracentral gyrus was associated with TBI due to IPV than TBI from other etiologies. Although preliminary, findings from this pilot study present a step toward identifying potential mechanisms by which IPV and TBI secondary to IPV impact brain health in women.

Exploring clinical and patient characteristics for rehabilitation referrals following a concussion: a retrospective analysis

Objective

To explore patterns of postconcussion care at a level 1 trauma center.

Design

Retrospective cohort study.

Setting

U.S. level 1 trauma center and local satellite units.

Participants

Patients of any age with a concussion diagnosis that reported to level 1 trauma center and local satellite units between 2016 and 2018 (N=2417).

Intervention

Not applicable.

Main Outcome Measures

Age, sex, point of entry, rehabilitation referrals, and pre-existing comorbidity diagnosis.

Results

Patient age (mean [SD]) significantly differed among points of entry, from youngest to oldest: 26.0 (14.0) years in sports medicine, 29.3 (23.0) years in the emergency department, 34.6 (23.6) years at primary care providers, and 46.0 (19.7) years at specialty care departments. Sex also significantly differed among points of entry; emergency departments reported more men (55.6%), whereas the other points of entry reported more women (59.3%-65.6%). Patients were more likely to receive a referral from sports medicine (odds ratio [OR]_unadjusted=75.05, P<.001), primary care providers (OR_unadjusted=7.98, P<.001), and specialty care departments (OR_unadjusted=7.62, P<.001) than from the emergency department. Women were more likely to receive a referral (OR_unadjusted=1.92, P<.0001), regardless of point of entry. Lastly, patients with a preexisting comorbidity were more likely (OR_adjusted=2.12, P<.001) to get a rehabilitation referral than patients without a comorbidity.

Conclusions

Point of entry, age, sex, and preexisting comorbidities are associated with postconcussion care rehabilitation referral patterns. Improving concussion education dissemination across all entry points of a level 1 trauma center may standardize the postconcussion rehabilitation referral patterns, potentially improving the time to recovery from a concussion.

Cellular Senescence in Traumatic Brain Injury: Evidence and Perspectives

Mild traumatic brain injury (mTBI) can lead to long-term neurological dysfunction and increase one's risk of neurodegenerative disease. Several repercussions of mTBI have been identified and well-studied, including neuroinflammation, gliosis, microgliosis, excitotoxicity, and proteinopathy – however the pathophysiological mechanisms activating these pathways after mTBI remains controversial and unclear. Emerging research suggests DNA damage-induced cellular senescence as a possible driver of mTBI-related sequalae. Cellular senescence is a state of chronic cell-cycle arrest and inflammation associated with physiological aging, mood disorders, dementia, and various neurodegenerative pathologies. This narrative review evaluates the existing studies which identify DNA damage or cellular senescence after TBI (including mild, moderate, and severe TBI) in both experimental animal models and human studies, and outlines how cellular senescence may functionally explain both the molecular and clinical manifestations of TBI. Studies on this subject clearly show accumulation of various forms of DNA damage (including oxidative damage, single-strand breaks, and double-strand breaks) and senescent cells after TBI, and indicate that cellular senescence may be an early event after TBI. Further studies are required to understand the role of sex, cell-type specific mechanisms, and temporal patterns, as senescence may be a pathway of interest to target for therapeutic purposes including prognosis and treatment.

Systematic Review of Sex and Gender Effects in Traumatic Brain Injury: Equity in Clinical and Functional Outcomes

Background: Although traumatic brain injury (TBI) is a leading cause of death and disability in male and female patients worldwide, little is known about the effect of sex and gender on TBI outcomes.

Objectives: This systematic review summarizes the evidence on the effect of sex and gender on core TBI outcomes.

Methods: All English-language studies from six literature databases that addressed core outcomes in adults with TBI and included sex or gender, TBI severity, and age in their analyses were considered eligible. Two reviewers extracted data, and two reviewers assessed study quality using tools recommended by the National Institutes of Health. The results were sorted according to time post-injury, injury severity, gender equity ranking of the study's country of origin, and outcomes studied. The results from the included studies were grouped based on the approach taken in reporting their respective findings.

Results and Limitations: Of 172 articles assessed, 58 studies were selected, comprising 1, 265, 955 participants with TBI (67% male across all studies) of all injury severities. All studies were conducted in countries with a very high or high human development index, while the Gender Inequality Index (GII) varied. While the heterogeneity across studies limited any meaningful conclusions with respect to the role of sex and gender, we did observe that as gender equality ranking improved, differences between male and female participants in outcomes would diminish. Inclusion of social equity parameters in the studies was limited.

Conclusions and Implications: The non-uniform findings observed bring forth the need to develop and use a comprehensive and consistent methodology in the study of sex and gender post-TBI, incorporating social equity parameters to uncover the potential social underpinnings of gender effects on health and functional outcomes.

Systematic Review Registration: CRD42018098697.

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.

Physical and Functional Impairment Among Older Adults With a History of Traumatic Brain Injury

OBJECTIVES

To examine the association of lifetime history of traumatic brain injury (TBI) with later-life physical impairment (PI) and functional impairment (FI) and to evaluate the impact of neurobehavioral symptoms that frequently co-occur with TBI on these relations.

PARTICIPANTS

A total of 1148 respondents to the 2014 Wave of the Health and Retirement Study, a nationally representative survey of older community-dwelling adults, randomly selected to participate in a TBI exposure survey. They reported no prior TBI (n = 737) or prior TBI (n = 411).

DESIGN

Cross-sectional survey study.

MAIN MEASURES

Physical impairment (self-reported difficulty with ≥1 of 8 physical activities); FI (self-reported difficulty with ≥1 of 11 activities of daily living); self-reported current neurobehavioral symptoms (pain, sleep problems, depression, subjective memory impairment); The Ohio State University TBI Identification Method (OSU-TBI-ID)-short form.

ANALYSES

Stepwise logistic regression models ([1] unadjusted; [2] adjusted for demographics and medical comorbidities; [3] additionally adjusted for neurobehavioral symptoms) compared PI and FI between TBI groups.

RESULTS

Traumatic brain injury-exposed (mean: 33.6 years postinjury) respondents were younger, less likely to be female, and reported more comorbidities and neurobehavioral symptoms. Although TBI was significantly associated with increased odds of PI and FI in unadjusted models and models adjusted for demographics/comorbidities (adjusted odds ratio, 95% confidence interval: PI 1.62, 1.21-2.17; FI 1.60, 1.20-2.14), this association was no longer statistically significant after further adjustment for neurobehavioral symptoms.

CONCLUSION

History of TBI is associated with substantial PI and FI among community-dwelling older adults. Further research is warranted to determine whether aggressive management of neurobehavioral symptoms in this population may mitigate long-term PI and FI in this population.

Post-traumatic headache attributed to traumatic brain injury: classification, clinical characteristics, and treatment

Post-traumatic headache is a common sequela of traumatic brain injury and is classified as a secondary headache disorder. In the past 10 years, considerable progress has been made to better understand the clinical features of this disorder, generating momentum to identify effective therapies. Post-traumatic headache is increasingly being recognised as a heterogeneous headache disorder, with patients often classified into subphenotypes that might be more responsive to specific therapies. Such considerations are not accounted for in three iterations of diagnostic criteria published by the International Headache Society. The scarcity of evidence-based approaches has left clinicians to choose therapies on the basis of the primary headache phenotype (eg, migraine and tension-type headache) and that are most compatible with the clinical picture. A concerted effort is needed to address these shortcomings and should include large prospective cohort studies as well as randomised controlled trials. This approach, in turn, will result in better disease characterisation and availability of evidence-based treatment options.

The Boston Assessment of Traumatic Brain Injury-Lifetime Semistructured Interview for Assessment of TBI and Subconcussive Injury Among Female Survivors of Intimate Partner Violence: Evidence of Research Utility and Validity

OBJECTIVE

To adapt the Boston Assessment of TBI-Lifetime (BAT-L) interview specifically for female survivors of intimate partner violence (IPV), validate the adapted BAT-L/IPV, and report the prevalence of head injury.

SETTING

The BAT-L is the first validated instrument to diagnose traumatic brain injuries (TBIs) throughout the life span for post-9/11 veterans. The BAT-L/IPV was adapted to target diagnostic issues belonging exclusively to IPV while maintaining its life span approach.

PARTICIPANTS

Community-dwelling convenience sample of 51 female survivors of IPV with subthreshold (n = 10) or full diagnostic criteria (n = 41) of posttraumatic stress disorder.

DESIGN

Standard TBI criteria were evaluated using a semistructured clinical interview.

MAIN MEASURES

The BAT-L/IPV is compared with the Ohio State University TBI Identification Method (OSU-TBI-ID) scoring approach as the criterion standard.

RESULTS

Correspondence between the BAT-L/IPV and the OSU-TBI-ID score was excellent (Cohen κ = 0.86; Kendall τ-b = 0.89). Sensitivity = 89.3% (95% CI, 81.2-97.4); specificity = 98.3% (95% CI, 95.0-100); positive predictive value = 98.0% (95% CI, 94.2-100); and negative predictive value = 90.6% (95% CI, 83.5-97.7). On the BAT-L/IPV, more than one-third (35.3%) of IPV survivors reported TBI secondary to an IPV-related assault, 76.5% reported IPV subconcussive head injury, 31.4% reported attempted strangulation, and 37.3% reported non-IPV TBI.

CONCLUSIONS

The BAT-L/IPV performed well in diagnosing TBI in female IPV survivors as compared with the criterion standard. The prevalence of TBI was frequent; subconcussive head injury was pervasive. Greater awareness for head injury risk and increased diagnostic specificity of TBI in IPV survivors is needed.

White Matter Hyperintensities Are Not Related to Symptomatology or Cognitive Functioning in Service Members with a Remote History of Traumatic Brain Injury

This study aimed to determine whether magnetic resonance imaging (MRI) white matter hyperintensities (WMHs) are associated with symptom reporting and/or cognitive performance in 1202 active-duty service members with prior single or multiple mild traumatic brain injury (mTBI). Patients with mTBI evaluated at the National Intrepid Center of Excellence (NICoE) at Walter Reed National Military Medical Center (WRNMMC) were divided into those with (n = 632) and without (n = 570) WMHs. The groups were compared on several self-report scales including the Neurobehavioral Symptom Inventory (NSI), Post-Traumatic Stress Disorder (PTSD) Checklist-Civilian Version (PCL-C), Satisfaction with Life Scale (SWLS), and Short Form-36 Health Survey (SF-36). They were also compared on several neuropsychological measures, including tests of attention, working memory, learning and memory, executive functioning, and psychomotor functioning. After correction for multiple comparisons, there were no significant differences between the two groups on any self-reported symptom scale or cognitive test. When comparing a subgroup with the highest (20+) WMH burden (n = 60) with those with no WMHs (n = 60; matched on age, education, sex, race, rank, and TBI number), only SF-36 Health Change significantly differed between the subgroups; the multiple WMH subgroup reported worsening health over the past year (t[53] = 3.52, p = 0.001, d = 0.67) compared with the no WMH subgroup. These findings build on prior research suggesting total WMHs are not associated with significant changes in self-reported symptoms or cognitive performance in patients with a remote history of mTBI. As such, clinicians are encouraged to use caution when reporting such imaging findings.

Inflammatory Regulation of CNS Barriers After Traumatic Brain Injury: A Tale Directed by Interleukin-1

Several barriers separate the central nervous system (CNS) from the rest of the body. These barriers are essential for regulating the movement of fluid, ions, molecules, and immune cells into and out of the brain parenchyma. Each CNS barrier is unique and highly dynamic. Endothelial cells, epithelial cells, pericytes, astrocytes, and other cellular constituents each have intricate functions that are essential to sustain the brain's health. Along with damaging neurons, a traumatic brain injury (TBI) also directly insults the CNS barrier-forming cells. Disruption to the barriers first occurs by physical damage to the cells, called the primary injury. Subsequently, during the secondary injury cascade, a further array of molecular and biochemical changes occurs at the barriers. These changes are focused on rebuilding and remodeling, as well as movement of immune cells and waste into and out of the brain. Secondary injury cascades further damage the CNS barriers. Inflammation is central to healthy remodeling of CNS barriers. However, inflammation, as a secondary pathology, also plays a role in the chronic disruption of the barriers' functions after TBI. The goal of this paper is to review the different barriers of the brain, including (1) the blood-brain barrier, (2) the blood-cerebrospinal fluid barrier, (3) the meningeal barrier, (4) the blood-retina barrier, and (5) the brain-lesion border. We then detail the changes at these barriers due to both primary and secondary injury following TBI and indicate areas open for future research and discoveries. Finally, we describe the unique function of the pro-inflammatory cytokine interleukin-1 as a central actor in the inflammatory regulation of CNS barrier function and dysfunction after a TBI.

Translational relevance of fear conditioning in rodent models of mild traumatic brain injury

Mild traumatic brain injury (mTBI) increases the risk of posttraumatic stress disorder (PTSD) in military populations. Utilizing translationally relevant animal models is imperative for establishing a platform to delineate neurobehavioral deficits common to clinical PTSD that emerge in the months to years following mTBI. Such platforms are required to facilitate preclinical development of novel therapeutics. First, this mini review provides an overview of the incidence of PTSD following mTBI in military service members. Secondly, the translational relevance of fear conditioning paradigms used in conjunction with mTBI in preclinical studies is evaluated. Next, this review addresses an important gap in the current preclinical literature; while incubation of fear has been studied in other areas of research, there are relatively few studies pertaining to the enhancement of cued and contextual fear memory over time following mTBI. Incubation of fear paradigms in conjunction with mTBI are proposed as a novel behavioral approach to advance this critical area of research. Lastly, this review discusses potential neurobiological substrates implicated in altered fear memory post mTBI.

Assessing lifetime exposure to traumatic brain injury among an international sample of Spanish speakers

BACKGROUND

With structured interviews being an established method for assessing one's exposure to traumatic brain injury across their lifetime, effective assessment tools are needed to serve the large population of Spanish speakers in the U.S. and abroad.

OBJECTIVE

To obtain preliminary evidence of validity for a Spanish version of a web-based, structured interview designed to assess lifetime exposure to TBI.

METHODS

A sample of 720 Spanish-speaking individuals between the ages of 18 through 65 from the continental U.S. (34.3%), South America (30.8%), the Caribbean (12.6%), Spain (12.4%), and Mexico and Central America (9.9%) completed an online survey containing the Ohio State University Traumatic Brain Injury Identification Method (Self-Administered-Brief; OSU TBI-ID SAB), Neurobehavioral Symptom Inventory, and PROMIS Cognitive Concerns Scale.

RESULTS

Indices of severity of worst TBI, time since most recent TBI, and multiple injuries demonstrated expected relationships with neurobehavioral symptoms such that greater symptom reporting was observed among those who had more severe injuries, more recent injuries, and multiple injuries over a period of time.

CONCLUSIONS

Findings provide preliminary evidence of validity for three of the indices derived from OSU TBI-ID SAB among Spanish-speaking individuals. Further study is needed to assess other aspects of this instrument to pave the way for further epidemiological studies involving lifetime exposure to TBI among Spanish-speaking individuals across the U.S., Spain, and Latin America.

Concussion and Risk of Chronic Medical and Behavioral Health Comorbidities

While chronic neurological effects from concussion have been studied widely, little is known about possible links between concussion and long-term medical and behavioral comorbidities. We performed a retrospective cohort study of 9205 adult patients with concussion, matched to non-concussion controls from a hospital-based electronic medical registry. Patients with comorbidities before the index visit were excluded. Behavioral and medical comorbidities were defined by International Classification of Diseases, Ninth and Tenth Revision codes. Groups were followed for up to 10 years to identify comorbidity incidence after a concussion. Cox proportional hazards models were used to calculate associations between concussion and comorbidities after multi-variable adjustment. Patients with concussion were 57% male (median age: 31; interquartile range [IQR] = 23-48 years) at enrollment with a median follow-up time of 6.1 years (IQR = 4.2-9.1) and well-matched to healthy controls. Most (83%) concussions were evaluated in outpatient settings (5% inpatient). During follow-up, we found significantly higher risks of cardiovascular risks developing including hypertension (hazard ratio [HR] = 1.7, 95% confidence interval [CI]: 1.5-1.9), obesity (HR = 1.7, 95% CI: 1.3-2.0), and diabetes mellitus (HR = 1.8, 95% CI: 1.4-2.3) in the concussion group compared with controls. Similarly, psychiatric and neurological disorders such as depression (HR = 3.0, 95% CI: 2.6-3.5), psychosis (HR = 6.0, 95% CI: 4.2-8.6), stroke (HR = 2.1 95% CI: 1.5-2.9), and epilepsy (HR = 4.4, 95% CI: 3.2-5.9) were higher in the concussion group. Most comorbidities developed less than five years post-concussion. The risks for post-concussion comorbidities were also higher in patients under 40 years old compared with controls. Patients with concussion demonstrated an increased risk of development of medical and behavioral health comorbidities. Prospective studies are warranted to better describe the burden of long-term comorbidities in patients with concussion.

Impaired visual working memory and reduced connectivity in undergraduates with a history of mild traumatic brain injury

Mild traumatic brain injury (mTBI), or concussion, accounts for 85% of all TBIs. Yet survivors anticipate full cognitive recovery within several months of injury, if not sooner, dependent upon the specific outcome/measure. Recovery is variable and deficits in executive function, e.g., working memory (WM) can persist years post-mTBI. We tested whether cognitive deficits persist in otherwise healthy undergraduates, as a conservative indicator for mTBI survivors at large. We collected WM performance (change detection, n-back tasks) using various stimuli (shapes, locations, letters; aurally presented numbers and letters), and wide-ranging cognitive assessments (e.g., RBANS). We replicated the observation of a general visual WM deficit, with preserved auditory WM. Surprisingly, visual WM deficits were equivalent in participants with a history of mTBI (mean 4.3 years post-injury) and in undergraduates with recent sports-related mTBI (mean 17 days post-injury). In seeking the underlying mechanism of these behavioral deficits, we collected resting state fMRI (rsfMRI) and EEG (rsEEG). RsfMRI revealed significantly reduced connectivity within WM-relevant networks (default mode, central executive, dorsal attention, salience), whereas rsEEG identified no differences (modularity, global efficiency, local efficiency). In summary, otherwise healthy current undergraduates with a history of mTBI present behavioral deficits with evidence of persistent disconnection long after full recovery is expected.

Athlete concussion history recall is underestimated: a validation study of self-reported concussion history among current professional rugby union players

Objective: To assess the concurrent validity and test re-test reliability of the Michigan Traumatic Brain Injury Identification Method (MTBIIM). The psychometric properties of this concussion index were investigated by comparing the agreement between player self-reported diagnosed concussions and medical record diagnosed concussions among professional rugby union players.Study Design: Cross-sectional study i) validation and ii) test re-test reliability.Methods: The MTBIIM was administered via a structured interview to obtain the number and nature of player self-reported concussion histories from players, while contracted to the host club. Self-reported concussion history information was compared to medically recorded data captured between 2008 and 2017. A mixed-effects logistic regression model explored predictors of player self-report accuracy.Results: Data from 62 players (25.39[4.36] years) included 99 unique rugby related concussions. Medically documented concussions (n = 92) per player (1.48 [1.96]) were 30% more than the mean number of self-reported diagnosed (n = 63) concussions per player (1.02 [1.21] events). Overall, self-reported diagnosed concussions and medical record diagnosed concussion histories had a 'fair' level of agreement (k=0.274; SE [0.076]), p=.001). Self-reported lifetime concussion history was signicantly negatively correlated with recall of concussions.Conclusions: Initial concurrent validity of the MTBIIM was found to be fair with the average athlete under-reporting the number of clinically diagnosed concussions.

Care of the Patient with Acquired Brain Injury in Latin America and the Caribbean

Traumatic brain injury and stroke are the leading causes of death and disability in Latin American and Caribbean countries. Specific characteristics, models of health care systems, and risk factors may influence the patient's outcome in this region. Relevant literature suggest that important delay problems exist in seeking care, reaching care, and receiving care in patients with acute neurologic injuries. Minimizing the time lost before care can be provided are vital to reduce the morbidity, long-term disability, and improved survival.

Investigating cannabis use and associated symptoms among university students with and without a history of concussion

Recently, there has been a growing interest in the use of cannabis after traumatic brain injury (TBI); however, little is known about the long-term effects of cannabis on milder injuries and post-concussive symptoms. Further, substance use often increases post-TBI and, thus, individuals who chronically use cannabis may unknowingly be exceeding safe or therapeutic doses. The current cross-sectional study explores the prevalence of cannabis use among university students with and without a history of concussion and examines the relationship between concussion and post-concussive symptoms as a function of cannabis use. Eighty-four undergraduates (n = 51 without a prior concussion; n = 33 with a prior concussion) completed a series of questionnaires, capturing their head injury history, current and past substance use, and post-concussive symptomatology. Results indicated that those with a history of concussion were more likely to use cannabis and had higher cannabis use severity scores compared to those without a previous concussion. Further, among cannabis users only, concussion severity demonstrated a significant positive association with post-concussive symptom (e.g., headaches, memory problems) severity (i.e., frequency, intensity, duration). Taken together, the long-term use of cannabis may be detrimental to individuals with a history of concussion, exacerbating, rather than mitigating, post-concussive symptoms.

Effect of concussion on salary and employment: a population-based event time study using a quasi-experimental design

OBJECTIVE

Concussions are the most frequent traumatic brain injuries. Yet, the socioeconomic impact of concussions remains unclear. Socioeconomic effects of concussions on working-age adults were studied on a population scale.

DESIGN

This population-based, event time study uses administrative data as well as hospital and emergency room records for the population of Denmark.

SETTING

We study all Danish patients, aged 20-59 years, who were treated at a public hospital or at an emergency room between 2003 and 2017 after suffering a concussion without other intracranial or extracranial injuries (n=55 424 unique individuals). None of the patients had a prior diagnosis of intracranial or extracranial injuries within the past 10 years leading up to the incident.

PRIMARY AND SECONDARY OUTCOME MEASURES

As primary endpoint, we investigate the mean effect of concussion on annual salaried income within a 5-year period after trauma. In an exploratory analysis, we study whether the potential impact of concussion on annual salaried income is driven by patient age, education or economic cycle.

RESULTS

Concussion was associated with an average change in annual salary income of -€1223 (95% CI: -€1540 to -905, p<0.001) corresponding to a salary change of -4.2% (95% CI: -5.2% to -3.1 %). People between 30 and 39 years and those without high school degrees suffered the largest salary decreases. Affected individuals leaving the workforce drove the main part of the decrease. Absolute annual effect sizes were countercyclical to the unemployment rate.

CONCLUSIONS

Concussions have a large and long-lasting impact on salary and employment of working-age adults on a nationwide scale.

Psychogenic Gait Disorder Complicating Recovery After Concussion: A Case Series

BACKGROUND

Gait impairment is common after concussion. "Dizziness" is associated with prolonged recovery after concussion. Most often each of these symptoms is considered to be of vestibular origin. However, whether or not there are psychological etiologies of gait instability that complicate concussion recovery has been less fully explored.

METHODS

A chart review was performed of all patients seen between 2017 and 2019 in a weekly pediatric traumatic brain injury clinic.

RESULTS

Of eighty-four patients with traumatic brain injury, five were found to have developed a classic psychogenic gait. All were adolescents at the time of diagnosis. Recognition of this complication led to modification/initiation of physical therapy and/or mental health intervention and eventual resolution for all patients.

CONCLUSION

Although uncommon, psychogenic gait disorders may complicate concussion recovery in adolescents likely at a higher rate than their occurrence in the general population. This association has not been previously reported. Accurate diagnosis of psychogenic gait likely improves outcomes in this subset of patients with concussion.

Self-Reported Concussion Symptomology during Deployment: Differences as a Function of Injury Mechanism and Low-Level Blast Exposure

Traumatic brain injury (TBI), which can result from either direct impact to the head or blast exposure, has been the leading cause of morbidity and mortality in recent military conflicts. However, little research has compared mTBIs by mechanism of injury. The present research addressed two research questions: (1) Are blast-related mTBIs (mbTBIs) associated with significantly more symptoms than impact-related mTBIs (miTBIs), and (2) are mTBIs associated with more self-reported symptoms among service members with higher (vs. lower) risk of low-level blast (LLB) exposure. We obtained data from 181,423 active duty enlisted United States Marines deployed between 2003 and 2012, who completed the Post-Deployment Health Assessment. We examined the self-reported symptoms of Marines who completed an mTBI screen and could be classified as at high or low risk for LLB exposure, using their military occupation as a proxy (n = 12,013). Symptoms were compared as a function of blast exposure (blast vs. impact), probable mTBI (yes vs. no), occupational risk of LLB (high vs. low), and symptom type (neurological vs. musculoskeletal vs. immunological). Overall, musculoskeletal symptoms were reported more frequently than neurological and immunological symptoms. However, Marines with probable mTBIs (regardless of mechanism of injury) and those with probable mbTBIs specifically reported more neurological symptoms, which rose to the level of musculoskeletal symptom reporting. Among Marines with probable mTBI, those with high risk of LLB exposure also reported significantly more neurological symptoms. Our results indicate that mbTBIs and miTBIs may be fundamentally different, and that LLB may increase susceptibility to injury.

Separate N-acetyl aspartyl glutamate, N-acetyl aspartate, aspartate, and glutamate quantification after pediatric mild traumatic brain injury in the acute phase

PURPOSE

To separately measure N-acetyl aspartul glutamate (NAAG), N-acetyl aspartate (NAA), aspartate (Asp), and glutamate (Glu) concentrations in white matter (WM) using J-editing techniques in patients with mild traumatic brain injury (mTBI) in the acute phase.

METHODS

Twenty-four patients with closed concussive head injury and 29 healthy volunteers were enrolled in the current study. For extended ¹ H MRS examination, patients and controls were equally divided into two subgroups. In subgroup 1 (12 patients/15 controls), NAAG and NAA concentrations were measured in WM separately with MEGA-PRESS (echo time/repetition time [TE/TR] = 140/2000 ms; δ ON NAA / δ OFF NAA = 4.84/4.38 ppm, δ ON NAAG / δ OFF NAAG = 4.61/4.15 ppm). In subgroup 2 (12 patients/14 controls), Asp and Glu concentrations were acquired with MEGA-PRESS (TE/TR = 90/2000 ms; δ ON Asp / δ OFF Asp = 3.89/5.21 ppm) and TE-averaged PRESS (TE from 35 ms to 185 ms with 2.5-ms increments; TR = 2000 ms) pulse sequences, respectively.

RESULTS

tNAA and NAAG concentrations were found to be reduced, while NAA concentrations were unchanged, after mild mTBI. Reduced Asp and elevated myo-inositol (mI) concentrations were also found.

CONCLUSION

The main finding of the study is that the tNAA signal reduction in WM after mTBI is associated with a decrease in the NAAG concentration rather than a decrease in the NAA concentration, as was thought previously. This finding highlights the importance of separating these signals, at least for WM studies, to avoid misinterpretation of the results. NAAG plays an important role in selectively activating mGluR3 receptors, thus providing neuroprotective and neuroreparative functions immediately after mTBI. NAAG shows potential for the development of new therapeutic strategies for patients with injuries of varying severity.