Systematic Review of the Prognosis After Mild Traumatic Brain Injury in Adults: Cognitive, Psychiatric, and Mortality Outcomes: Results of the International Collaboration on Mild Traumatic Brain Injury Prognosis

Repetitive traumatic brain injury-induced complement C1-related inflammation impairs long-term hippocampal neurogenesis

JOURNAL/nrgr/04.03/01300535-202503000-00027/figure1/v/2024-06-17T092413Z/r/image-tiff Repetitive traumatic brain injury impacts adult neurogenesis in the hippocampal dentate gyrus, leading to long-term cognitive impairment. However, the mechanism underlying this neurogenesis impairment remains unknown. In this study, we established a male mouse model of repetitive traumatic brain injury and performed long-term evaluation of neurogenesis of the hippocampal dentate gyrus after repetitive traumatic brain injury. Our results showed that repetitive traumatic brain injury inhibited neural stem cell proliferation and development, delayed neuronal maturation, and reduced the complexity of neuronal dendrites and spines. Mice with repetitive traumatic brain injuryalso showed deficits in spatial memory retrieval. Moreover, following repetitive traumatic brain injury, neuroinflammation was enhanced in the neurogenesis microenvironment where C1q levels were increased, C1q binding protein levels were decreased, and canonical Wnt/β-catenin signaling was downregulated. An inhibitor of C1 reversed the long-term impairment of neurogenesis induced by repetitive traumatic brain injury and improved neurological function. These findings suggest that repetitive traumatic brain injury-induced C1-related inflammation impairs long-term neurogenesis in the dentate gyrus and contributes to spatial memory retrieval dysfunction.

Neuropsychological Evaluation in Traumatic Brain Injury

Neuropsychological evaluations can be helpful in the aftermath of traumatic brain injury. Cognitive functioning is assessed using standardized assessment tools and by comparing an individual's scores on testing to normative data. These evaluations examine objective cognitive functioning as well as other factors that have been shown to influence performance on cognitive tests (eg, psychiatric conditions, sleep) in an attempt to answer a specific question from referring providers. Referral questions may focus on the extent of impairment, the trajectory of recovery, or ability to return to work, sport, or the other previous activity.

Pre-injury psychiatric history, subacute symptoms and personality traits predict social reintegration at 3-month post-mild traumatic brain injury

BACKGROUND

The purpose of the study was to identify whether the presence of a pre-injury psychiatric history, subacute post-concussive symptoms (PCS) and personality traits were predictive of less favorable social reintegration for 3 months following a mild traumatic brain injury (mTBI).

METHOD

A total of 76 patients with mTBI were included, and the presence of a pre-injury psychiatric history was identified from the medical chart. One-month post-accident, these patients completed the Millon Multiaxial Clinical Inventory, 3rd Edition assessing personality traits and the Rivermead Post-Concussion Symptoms Questionnaire to measure subacute PCS. Social reintegration was measured using the Mayo-Portland Adaptability Inventory, 4th Edition at 3-month post-accident.

RESULTS

The presence of pre-injury psychiatric history, high levels of subacute PCS and Cluster B personality traits such as histrionic and borderline features were significant predictors of social reintegration quality at 3-month post injury.

CONCLUSION

This study provides new insights on cluster B personality traits and its influence on recovery and social reintegration at 3-month post mTBI.

Time to resolution of symptoms and recovery after mild traumatic brain injury: protocol for a systematic review and meta-analysis

INTRODUCTION

Mild traumatic brain injury (mTBI) is a leading cause of morbidity and mortality, with approximately 1 out of 200 people each year sustaining an mTBI in Europe. There is a growing awareness that recovery may take months or years. However, the exact time frame of recovery remains ill-defined in the literature. This systematic review aims to record the range of outcome measures used for mTBI and understand the time to recovery for different outcomes.

METHODS AND ANALYSIS

This protocol complies with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guideline. A prespecified literature search for articles in the English language will be conducted from database inception to the date of searches using MEDLINE and EMBASE. A trial search was conducted on 5 October 2023 with refinement of the search criteria following this. For each study, screening of the title, abstract and full text, as well as data extraction, will be done by two reviewers, with an adjudicating third reviewer if required. The risk of bias will be assessed using the Cochrane risk of bias tool for clinical trials and the Newcastle Ottawa score for cohort studies. The primary outcome is the time to resolution of symptoms in mTBI patients who have a full recovery, using any validated outcome measure. Results will be categorised by symptom groups, including but not limited to post-concussive symptoms, mental health, functional recovery and health-related quality of life. For mTBI patients who do not recover, this review will also explore the time to the plateau of symptoms and the sequelae of these symptoms. Where possible, meta-analysis will be undertaken, with a narrative review undertaken when this is not possible. Subgroup analyses of patients aged over 64 years, and patients with repetitive head injury, are planned.

ETHICAL REVIEW AND DISSEMINATION

Ethical review is not required, as no original data will be collected. Results will be disseminated through peer-reviewed publications and academic conferences.

PROSPERO REGISTRATION NUMBER

CRD42023462797.

Nature-Based Therapeutic Intervention for Individuals with Post-Concussion Symptoms

This study investigated the efficacy of a 10-session nature-based therapeutic intervention for people with post-concussion symptoms. The intervention involved physical and vestibular exercises, sensory training, relaxation, and psychoeducation, all of which were integrated with the natural environment in a forest therapy garden. This study was designed with a passive control period followed by the intervention (n = 30). The Mental Fatigue Scale (MFS) was the primary outcome measure. The secondary outcome measures were the Warwick-Edinburg Mental Wellbeing Scale and the short version of the Quality of Life after Brain Injury. A Likert scale was used to examine the mental strain of the sessions themselves. The MFS (primary outcome) exhibited a significant decrease with a medium-sized effect from before to after the intervention. The secondary outcomes exhibited significant increases from the beginning to the end of the intervention. All outcomes were sustained at follow-up ten weeks later. No significant difference was found from the control period. This study indicates that the described nature-based intervention is a feasible treatment for reducing prolonged post-concussion symptoms. However, it should be studied more in-depth to understand the impact of the natural environment and to validate the results on a larger representative population.

Personalized, parcel-guided non-invasive transcranial magnetic stimulation for the treatment of post-concussive syndrome: safety and proof of concept

OBJECTIVE

To determine the safety and proof of concept of a parcel-guided, repetitive Transcranial Magnetic Stimulation (rTMS) in patients who develop a heterogeneous array of symptoms, known collectively as post-concussive syndrome (PCS), following traumatic brain injury (TBI).

METHODS

We performed a retrospective review of off-label, individualized, parcel-guided rTMS in 19 patients from December 2020 to May 2023. Patients had at least one instance of mild, moderate, or severe TBI and developed symptoms not present prior to injury. rTMS targets were identified based on machine learning connectomic software using functional connectivity anomaly matrices compared to healthy controls. EuroQol (EQ-5D), as a measurement of quality of life, and additional questionnaires dependent on individual's symptoms were submitted prior to, after, and during follow-up from rTMS.

RESULTS

Nineteen patients showed improvement in EQ-5D and Rivermead Post Concussion Symptoms Questionnaires - 3 after treatment and follow-up. For nine patients who developed depression, five (55%) attained response and remission based on the Beck Depression Inventory after treatment. Eight of ten patients with anxiety had a clinically significant reduction in Generalized Anxiety Disorder-7 scores during follow-up.

CONCLUSION

Parcel-guided rTMS is safe and may be effective in reducing PCS symptoms following TBI and should incite further controlled studies.

The Cognitive Profile of Elderly Patients With Mild Traumatic Brain Injury: A Role for Cognitive Reserve?

OBJECTIVE

To assess cognitive status in elderly patients with mild traumatic brain injury (mTBI) in the subacute phase, examine the role of cognitive reserve, and investigate associations with cognitive complaints, mental distress, and functional outcomes.

SETTING

A level 1 trauma center in the Netherlands.

PARTICIPANTS

A total of 52 individuals with mTBI and 42 healthy controls.

DESIGN

A prospective observational cohort study.

MAIN MEASURES

Neuropsychological assessment in the subacute phase (2 weeks to 6 months post-injury) to objectively measure the cognitive functioning, the Head Injury Symptom Checklist for subjective cognitive complaints, the Hospital Anxiety and Depression Scale for anxiety and depression, the Cognitive Reserve Index questionnaire for cognitive reserve, the Community Integration Questionnaire for community integration, and the Glasgow Outcome Scale Extended for functional outcome.

RESULTS

Cognitive impairments were observed in memory ( P < .001) and attention, processing speed and executive control ( P < .001). Cognitive reserve was not associated with neuropsychological test performance, except for one test measuring working memory. The relationship between injury severity and cognitive outcome was not moderated by cognitive reserve. Elderly patients reported significantly more complains than healthy controls regarding forgetfulness, concentration problems, and slowness. Complaints of concentration were associated with cognitive impairment. All cognitive complaints were significantly correlated with mental distress.

CONCLUSIONS

Cognitive impairments may be present in elderly patients in the subacute phase after mTBI, and these impairments were not significantly associated with cognitive reserve. This suggests that cognitive reserve might not serve as a protective factor against the effects of mTBI in the elderly. Concentration complaints may serve as a specific indicator for cognitive impairment, while complaints of memory and mental slowness may represent more generic indicators of mental distress. These findings highlight the importance of careful screening in older adults with mTBI, guiding clinicians toward specific treatment targets encompassing cognitive impairment, diminished mental well-being, or both.

A literature review of outcome and treatment options after acquired brain injury: Suggestions for adult offenders using knowledge from the general population

BACKGROUND

Acquired brain injury (ABI) is a major health problem, often with negative effects on behaviour and mental health as well as cognition. Prevalence of ABI is exceptionally high among offenders and increases their re-offending risk. Information on risk factors for ABI and its outcomes among offenders that could guide effective treatment for them is, nevertheless, scarce and dispersed. However, there is a more substantial literature about the general population that could inform work with brain-injured offenders, especially when selecting for samples or subgroups with similar relevant characteristics, such as lower socio-economic status (SES), pre-injury lower tested intelligence score (<85) and pre-injury mental health problems.

AIMS

To explore brain injury data from non-offender samples of otherwise similar socio-economic and mental health and ability characteristics to offenders then, first, to describe their untreated outcomes and, secondly, outcomes after frequently used interventions in these circumstances, noting factors associated with their effectiveness.

METHOD

Three databases were systematically searched for the years 2010-2022; first, using terms for brain injury or damage and cognitive (dys)function, mental health or quality of life. Second, in a separate search, we used these terms and terms for interventions and rehabilitation. In the second review, studies were selected for clear, distinguishable data on age, sex, SES and lifestyle factors to facilitate inferences for offenders. A narrative analytical approach was adopted for both reviews.

RESULTS

Samples with characteristics that are typical in offender groups, including lower SES, lower pre-injury intelligence quotient (<85), prior cognitive impairments and prior mental health problems, had poorer cognitive and behavioural outcomes following ABI than those without such additional problems, together with lower treatment adherence. With respect to treatment, adequate motivation and self-awareness were associated with better cognitive and behavioural outcomes than when these were low or absent, regardless of the outcome measured.

CONCLUSIONS

More complex pre-injury mental health problems and social disadvantages typical of offenders are associated with poorer post-brain injury recovery. This paper adds to practical knowledge by bringing together work that follows specific outcome trajectories. Overall, succesful ABI-interventions in the general population that aim at pre-injury difficulties comparable to those seen among offenders, show that personalising injury-specific treatments and taking account of these difficulties, maximised positive outcomes.

Heterogeneity of health-related quality of life after mild traumatic brain injury with systemic injury: a cluster analytic approach

PURPOSE

Health-related quality of life (HRQoL) is a key component of evaluating outcome after mild traumatic brain injury (mTBI). As outcome is heterogeneous following mTBI, it is relevant to examine individual differences in HRQoL. This study investigated whether multiple homogenous subgroups could be meaningfully identified, 10 weeks after hospitalised mTBI with systemic injury, on the basis of HRQoL profiles.

METHODS

Ninety-one adults were assessed for HRQoL, pain, fatigue, sleep quality, psychological distress, cognition and post-concussion symptoms.

RESULTS

Cluster analyses revealed three separate subgroups based on physical, mental, social and energy HRQoL. One group (42%) demonstrated normative levels of HRQoL on all subdomains. The remaining two groups demonstrated significantly reduced HRQoL on all subdomains. These groups had equivalently poor mental, social and energy HRQoL, but the smallest group (27%) had significantly poorer physical HRQoL. Multinomial logistic regression revealed that pain significantly and independently predicted group membership for the particularly poor physical HRQoL group. Fatigue was the only significant independent predictor of group membership for the remaining group with reduced HRQoL.

CONCLUSION

These findings suggest more than 50% of hospitalised individuals with mTBI and systemic injury, have reduced HRQoL, 10 weeks after mTBI. Pain and fatigue warrant clinical attention in these individuals.IMPLICATIONS FOR REHABILITATIONMild traumatic brain injury is a common event that has been shown to be associated with persistently reduced health-related quality of life in approximately 50% of individuals 6 to 12 months after injury.Health-related quality of life likely varies between individuals after injuryRelative to the "normal" population, most individuals in this cohort of individuals with mTBI and systemic injury had reduced mental, social and energy quality of life 10 weeks after injury.Fatigue and pain are important factors in reduced health-related quality of life after mTBI with systemic injury.Further research is needed to determine whether these fatigue and pain issues are related to mTBI-factors, such as headache, and/or related to systemic injury factors, which are common in the mTBI population.

Predictive Utility of Diffusion MRI After Mild Traumatic Brain Injury in Civilian Populations: A Systematic Review

OBJECTIVE

A considerable number of people experience persisting symptoms and functional limitations after mild traumatic brain injury (mTBI). It is unclear whether subtle white matter changes contribute to this phenomenon. In this systematic review, the authors evaluated whether microstructural white matter indices on advanced MRI are related to clinical dysfunction among patients without abnormalities on standard brain computed tomography (CT) or MRI (uncomplicated mTBI).

METHODS

A search of multiple databases was performed. Studies with individuals who experienced blast-related, sports-related, or multiple mTBIs were excluded. Diffusion tensor imaging (DTI) and susceptibility-weighted imaging (SWI) metrics and cognitive, neuropsychiatric, or functional outcome measures were extracted from each study.

RESULTS

Thirteen studies were selected (participants with mTBI, N=553; healthy control group, N=438). Seven DTI studies evaluated cognitive function, with five reporting significant correlations between reduced white matter integrity and deficits in attention, processing speed, and executive function at 6-12 months after injury (three studies included only individuals with uncomplicated mTBI). Four studies found significant correlations between DTI metrics and persistent postconcussive symptoms after 3-12 months (one study included only individuals with uncomplicated mTBI). Two SWI studies reported conflicting findings regarding the relationship between the presence of microbleeds and postconcussive symptoms.

CONCLUSIONS

The results revealed that indices of microstructural white matter integrity may relate to clinical presentation 3-12 months after injury in uncomplicated mTBI. However, analysis methods and brain regions studied varied across studies. Further research is needed to identify relationships between white matter indices in specific brain regions and symptom persistence beyond 12 months.

Longitudinal recovery of executive functions and social participation prediction following traumatic brain injury

There is heterogeneity across studies and a lack of knowledge about recovery of EFs over time following traumatic brain injury (TBI). Also, EFs are associated with functional outcome, but there is still a gap in knowledge concerning the association between EFs and social participation following TBI. For this reason, we aim to (1) measure the recovery of the three executive function subcomponents of Miyake's model, namely flexibility, updating and inhibition between the acute phase (T1) and 6 months post TBI (T2) and (2) measure the relationship between EFs and social participation after TBI. Thus, a prospective longitudinal study that included 75 patients with TBI (mild and moderate-severe) and 50 patients with orthopedic injuries (controls) without brain damage was carried out. An extensive EFs test battery was administered at T1 and T2 whereas the Mayo-Portland Adaptability Inventory-4 (MPAI-4) was administered only at T2. In contrast with the controls, both TBI groups improved significantly between T1 and T2 on WMS-III Mental Control test (MC) and the D-KEFS Category Switching Condition of the Verbal Fluency task (SVF). Results also showed a simple time effect for the WAIS-IV Digit span and the Hayling tests. Moreover, there was an association between the SVF test and social participation (MPAI-4) at T2. In conclusion, the MC and SVF tests were found to be the best tools for measuring recovery of EFs following TBI. The SVF test was the most likely measure of EFs to give the neuropsychologist an idea of the patient's social participation.

Pediatric traumatic brain injury as a risk factor for psychosis and psychotic symptoms: a systematic review and meta-analysis

BACKGROUND

Psychosis is one of the most disabling psychiatric disorders. Pediatric traumatic brain injury (pTBI) has been cited as a developmental risk factor for psychosis, however this association has never been assessed meta-analytically.

METHODS

A systematic review and meta-analysis of the association between pTBI and subsequent psychotic disorders/symptoms was performed. The study was pre-registered (CRD42022360772) adopting a random-effects model to estimate meta-analytic odds ratio (OR) and 95% confidence interval (CI) using the Paule-Mandel estimator. Subgroup (study location, study design, psychotic disorder v. subthreshold symptoms, assessment type, and adult v. adolescent onset) and meta-regression (quality of evidence) analyses were also performed. The robustness of findings was assessed through sensitivity analyses. The meta-analysis is available online as a computational notebook with an open dataset.

RESULTS

We identified 10 relevant studies and eight were included in the meta-analysis. Based on a pooled sample size of 479686, the pooled OR for the association between pTBI and psychosis outcomes was 1.80 (95% CI 1.11-2.95). There were no subgroup effects and no outliers. Both psychotic disorder and subthreshold symptoms were associated with pTBI. The overall association remained robust after removal of low-quality studies, however the OR reduced to 1.43 (95% CI 1.04-1.98). A leave-one-out sensitivity analysis showed the association was robust to removal of all but one study which changed the estimate to marginally non-significant.

CONCLUSIONS

We report cautious meta-analytic evidence for a positive association between pTBI and future psychosis. New evidence will be key in determining long-term reliability of this finding.

Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury

Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology.

Labour market attachment dynamics in patients with concussion: a Danish nationwide register-based cohort study

BACKGROUND

Concussion may lead to persisting post-concussive symptoms affecting work ability and employment. This study examined the transitions between labour market states an individual can experience after the acute phase of concussion. The aim was to describe the incidence of favourable and adverse transitions between different labour market states (e.g., employment, sick leave) in relation to socioeconomic and health characteristics in individuals with concussion relative to matched controls.

METHODS

This Danish nationwide register-based cohort study extracted 18-60-year-old individuals between 2003-2007 with concussion from the Danish National Patient Register (ICD-10 S06.0). Controls were matched on age, sex, and municipality. Patients and controls were followed for 5 years starting three months after injury. Exclusion criteria were neurological injuries and unavailability to the labour market in the inclusion period (2003-2007) and 5-years before injury (1998-2002). Labour market states were defined from transfer income data in the Danish Register for Evaluation of Marginalization. Incidence rates of transitions between these labour market states were analysed in multistate models. Transitions were bundled in favourable and adverse transitions between labour market states and the difference in incidence rates between individuals with concussion relative to matched controls were assessed with hazard ratios from Cox regression models.

RESULTS

Persons with concussion (n = 15.580) had a lower incidence of favourable transitions (HR 0.88, CI 0.86-0.90) and a higher incidence of adverse transitions (HR 1.30, CI 1.27-1.35), relative to matched controls (n = 16.377). The effect of concussion differed depending on health and socioeconomic characteristics. Notably, individuals between 30-39 years (HR 0.83, CI 0.79-0.87), individuals with high-income (200.000-300.000 DKK) (HR 0.83, CI 0.80-0.87), and wage earners with management experience (HR 0.60, CI 0.44-0.81) had a markedly lower incidence of favourable transitions compared to controls. Additionally, individuals with high income also had a higher incidence of adverse transitions (HR 1.46, CI 1.34-1.58) compared to controls.

CONCLUSIONS

Concussion was associated with enhanced risk of adverse transitions between labour market states and lower occurrence of favourable transitions, indicating work disability, potentially due to persistent post-concussive symptoms. Some age groups, individuals with high income, and employees with management experience may be more affected.

The impact of minimum unit pricing on traumatic brain injury in Scotland: a retrospective cohort study of routine national data

BACKGROUND

Traumatic brain injury (TBI) is a common cause of disability and mortality and is associated with alcohol consumption. On 1st May 2018, the Scottish Government introduced Minimum Unit Pricing (MUP) legislation which set the floor price at which alcohol can be sold to 50 pence per unit. While MUP has led to a 7.6% decrease in off trade alcohol purchases, there are limited studies investigating the clinical impact of this legislation. This study aims to explore the impact of MUP on traumatic brain injury in Scotland.

METHODS

Retrospective cohort study using routinely collected national data collated by the Scottish Trauma Audit Group. Data were requested for all TBI incidents from 1st May to 31st December for both 2017 and 2018. Primary outcome was alcohol-related TBI. Secondary outcomes were injury mechanism, injury severity, clinical course, and short-term mortality. Analysis was conducted using multiple regression models adjusted for age, sex, season, and deprivation.

RESULTS

A total of 1166 patients (66% male, and 46% in the 60-79-year bracket) were identified. Alcohol-related TBI was evident in 184 of 509 (36%) patients before MUP and in 239 of 657 (36%) patients injured after its implementation (p = 0.638). Further, there was no change in injury mechanism, injury severity, hospital course and short-term mortality of TBI after MUP.

CONCLUSIONS

MUP has not resulted in a change in alcohol-related TBI nor in the mechanism and severity of TBI. Limitations in two-point analysis mean that findings should be interpreted with caution and further studies investigating the clinical outcomes of MUP must be conducted.

Cerebral microhaemorrhage count is related to processing speed, but not level of symptom reporting, independently of age, psychological status and premorbid functioning, after first-ever mild traumatic brain injury

Cerebral microhaemorrhage is a commonly identified neuropathological consequence of mild traumatic brain injury (mTBI) and can be identified in vivo using susceptibility weighted imaging (SWI). This study aimed to determine whether SWI-detected microhaemorrhages are more common in individuals after a single, first-ever, mTBI event relative to trauma controls (TC) and to investigate whether a linear relationship exists between microhaemorrhage numbers and cognition or symptom reporting in the post-acute period after injury, independently of age, psychological status and premorbid level of functioning. Microhaemorrhagic lesions were identified by expert clinical examination of SWI for 78 premorbidly healthy adult participants who were admitted to hospital after a traumatic injury and had suffered a first-ever mTBI (n = 47) or no head strike (n = 31). Participants underwent objective cognitive examination of processing speed, attention, memory, and executive function as well as self-reported post-concussion symptomatology. Bootstrapping analyses were used as data were not normally distributed. Analyses revealed that the mTBI group had significantly more microhaemorrhages than the TC group (Cohen's d = 0.559). These lesions were only evident in 28% of individuals. The mTBI participants demonstrated a significant linear association between number of microhaemorrhages and processing speed, independently of age, psychological status, or premorbid level of functioning. This study shows that a single mTBI causes cerebral microhaemorrhages to occur in a minority of premorbidly healthy individuals. Greater microhaemorrhage count is independently associated with slower processing speed, but not symptom reporting, during the post-acute injury period.

A comprehensive characterization of cognitive performance, clinical symptoms, and cortical activity following mild traumatic brain injury (mTBI)

OBJECTIVE

The objective of this study was to investigate clinical symptoms, cognitive performance and cortical activity following mild traumatic brain injury (mTBI).

METHODS

We recruited 30 individuals in the sub-acute phase post mTBI and 28 healthy controls with no history of head injury and compared these groups on clinical, cognitive and cortical activity measures. Measures of cortical activity included; resting state electroencephalography (EEG), task related EEG and combined transcranial magnetic stimulation with electroencephalography (TMS-EEG). Primary analyses investigated clinical, cognitive and cortical activity differences between groups. Exploratory analyses investigated the relationships between these measures.

RESULTS

At 4 weeks' post injury, mTBI participants exhibited significantly greater post concussive and clinical symptoms compared to controls; as well as reduced cognitive performance on verbal learning and working memory measures. mTBI participants demonstrated alterations in cortical activity while at rest and in response to stimulation with TMS.

CONCLUSIONS

The present study comprehensively characterized the multidimensional effect of mTBI in the sub-acute phase post injury, showing a broad range of differences compared to non-mTBI participants. Further research is needed to explore the relationship between these pathophysiologies and clinical/cognitive symptoms in mTBI.

Subjective cognitive complaints and objective cognitive functioning in combat veterans: Effects of PTSD and deployment mild TBI

OBJECTIVES

(1) Examine the relationship between subjective cognitive complaints and objective cognitive functioning in combat veterans; and (2) evaluate conditional effects of posttraumatic stress disorder (PTSD) and deployment-related mild traumatic brain injury (TBI) within that relationship.

METHOD

Combat veterans (N = 225, 86.22% male) completed a lifetime TBI interview, a structured interview assessing PTSD symptoms, a neuropsychological assessment battery, and a self-report measure of cognitive symptoms.

RESULTS

All correlations between subjective cognitive complaints and objective cognitive measures were not statistically significant. Hierarchical linear regression indicated that cognitive performance was not significantly related to cognitive complaints, but both PTSD diagnosis and history of deployment mild TBI explained a significant amount of unique variance in self-reported cognitive symptoms. Interactions between the studied variables were not significant.

CONCLUSIONS

PTSD and history of deployment mild TBI were uniquely related to cognitive complaints, but cognitive test performance was not. No confounding effects of PTSD or deployment mild TBI were observed in the relationship between cognitive performance and cognitive complaints. This provides support that symptom distress may be a better explanatory factor for perception of lower cognitive functioning than actual cognitive performance.

The relationship between cognition and white matter tract damage after mild traumatic brain injury in a premorbidly healthy, hospitalised adult cohort during the post-acute period

Introduction

Recent developments in neuroimaging techniques enable increasingly sensitive consideration of the cognitive impact of damage to white matter tract (WMT) microstructural organisation after mild traumatic brain injury (mTBI).

Objective

This study investigated the relationship between WMT microstructural properties and cognitive performance.

Participants setting and design

Using an observational design, a group of 26 premorbidly healthy adults with mTBI and a group of 20 premorbidly healthy trauma control (TC) participants who were well-matched on age, sex, premorbid functioning and a range of physical, psychological and trauma-related variables, were recruited following hospital admission for traumatic injury.

Main measures

All participants underwent comprehensive unblinded neuropsychological examination and structural neuroimaging as outpatients 6-10 weeks after injury. Neuropsychological examination included measures of speed of processing, attention, memory, executive function, affective state, pain, fatigue and self-reported outcome. The WMT microstructural properties were estimated using both diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) modelling techniques. Tract properties were compared between the corpus callosum, inferior longitudinal fasciculus, uncinate fasciculus, anterior corona radiata and three segmented sections of the superior longitudinal fasciculus.

Results

For the TC group, in all investigated tracts, with the exception of the uncinate fasciculus, two DTI metrics (fractional anisotropy and apparent diffusion coefficient) and one NODDI metric (intra-cellular volume fraction) revealed expected predictive linear relationships between extent of WMT microstructural organisation and processing speed, memory and executive function. The mTBI group showed a strikingly different pattern relative to the TC group, with no relationships evident between WMT microstructural organisation and cognition on most tracts.

Conclusion

These findings indicate that the predictive relationship that normally exists in adults between WMT microstructural organisation and cognition, is significantly disrupted 6-10 weeks after mTBI and suggests that WMT microstructural organisation and cognitive function have disparate recovery trajectories.

A Morphologically Individualized Deep Learning Brain Injury Model

The brain injury modeling community has recommended improving model subject specificity and simulation efficiency. Here, we extend an instantaneous (< 1 sec) convolutional neural network (CNN) brain model based on the anisotropic Worcester Head Injury Model (WHIM) V1.0 to account for strain differences due to individual morphological variations. Linear scaling factors relative to the generic WHIM along the three anatomical axes are used as additional CNN inputs. To generate training samples, the WHIM is randomly scaled to pair with augmented head impacts randomly generated from real-world data for simulation. An estimation of voxelized peak maximum principal strain of the whole-brain is said to be successful when the linear regression slope and Pearson's correlation coefficient relative to directly simulated do not deviate from 1.0 (when identical) by more than 0.1. Despite a modest training dataset (N = 1363 vs. ∼5.7 k previously), the individualized CNN achieves a success rate of 86.2% in cross-validation for scaled model responses, and 92.1% for independent generic model testing for impacts considered as complete capture of kinematic events. Using 11 scaled subject-specific models (with scaling factors determined from pre-established regression models based on head dimensions and sex and age information, and notably, without neuroimages), the morphologically individualized CNN remains accurate for impacts that also yield successful estimations for the generic WHIM. The individualized CNN instantly estimates subject-specific and spatially detailed peak strains of the entire brain and thus, supersedes others that report a scalar peak strain value incapable of informing the location of occurrence. This tool could be especially useful for youths and females due to their anticipated greater morphological differences relative to the generic model, even without the need for individual neuroimages. It has potential for a wide range of applications for injury mitigation purposes and the design of head protective gears. The voxelized strains also allow for convenient data sharing and promote collaboration among research groups.

Quality of life and psychological health after mild traumatic brain injury in older people: Three- and six-month follow up

OBJECTIVES

Examine quality of life (QoL) and psychological health after mild traumatic brain injury (mTBI) in older people (65+ years) at 3- and 6-month follow-up and explore which injury factors predicted QoL.

METHODS

mTBI patients were compared to trauma comparison (TC) and community comparison (CC) groups. QoL and psychological health were measured at both timepoints. After accounting for 3-month psychological health, injury severity, neuroimaging, and 3-month neuropsychological performance were assessed as predictors of 6-month QoL.

RESULTS

Overall 3-month QoL was lower for mTBI (Cohen's d = 0.938) and TC (Cohen's d = 0.485) groups compared to CCs, but by 6 months only mTBI patients continued to report poorer overall QoL (Cohen's d = 0.577) and physical QoL (Cohen's d = 0.656). Despite group differences, QoL for most (~92%) was within normative limits. 3-month psychological health predicted QoL 6-months postinjury (β = -.377, 95% CI -.614, -.140) but other proposed risk factors (GCS <15, neuroimaging, 3-month neuropsychological performance) did not uniquely predict QoL.

CONCLUSIONS

Older adults following mTBI reported lower QoL up to 6-months postinjury compared to non-injured peers, indicating that mTBI patients were particularly susceptible to ongoing differences in QoL 6-months postinjury.

Association Between First Attempt Buffalo Concussion Treadmill Test and Days to Recovery in 855 Children With Sport-Related Concussion: A Historical Cohort Study and Prognostic Factors Analysis

OBJECTIVE

Little is known about the prognostic value of the Buffalo Concussion Treadmill Test (BCTT) after the acute phase of sport-related concussion (SRC). We examined the added prognostic value of the BCTT performed 10 to 21 days after SRC in children, in addition to participant, injury, and clinical process characteristics on days to recovery.

DESIGN

Historical clinical cohort study.

SETTING

Network of approximately 150 Canadian multidisciplinary primary-care clinics.

PARTICIPANTS

855 children (mean age 14 years, range 6-17 years, 44% female) who presented between January 2016, and April 2019 with SRC.

ASSESSMENT OF RISK FACTORS

Participant, injury, and clinical process characteristics, with focus on BCTT exercise intolerance assessed 10 to 21 days after injury.

OUTCOME

Days to clinical recovery.

RESULTS

Children who were exercise intolerant experienced an increase of 13 days to recovery (95% CI, 9-18 days). Each additional day between SRC and first BCTT was associated with a recovery delay of 1 day (95% CI, 1-2 days), and prior history of concussion was associated with a recovery delay of 3 days (95% CI, 1-5 days). Participant, injury, and clinical process characteristics, and the first attempt BCTT result explained 11% of the variation in recovery time, with 4% accounted for by the BCTT.

CONCLUSION

Exercise-intolerance assessed 10 to 21 days after SRC was associated with delayed recovery. However, this was not a strong prognostic factor for days to recovery.

Associations between health-related behaviors and self-reported cognitive symptoms in U.S. military personnel injured on deployment

Health behaviors may be core contributors to cognition and mental health following mild traumatic brain injury (TBI). The aims of the present study examined: (1) whether health behaviors including sleep duration, alcohol use, and physical activity differed in injured military personnel with and without deployment-related mild TBI history and (2) the relative contributions of health behaviors and deployment-related mild TBI history to self-reported cognitive, posttraumatic stress disorder (PTSD), and depressive symptoms. Participants included 3076 military personnel injured on deployment participating in the Wounded Warrior Recovery Project, an ongoing web-based study. Military personnel with deployment-related mild TBI history reported similar rates of physical activity and levels of alcohol problems as those without, but were less likely to report receiving the recommended duration of sleep. When adjusting for demographic and injury variables, all three health behaviors were associated with cognitive, PTSD, and depressive symptoms. Alcohol problems demonstrated significant but small effects across all outcomes measures (ηp2=.01) whereas physical activity was associated with slightly larger effects albeit still within the small range (ηp2=.02-0.04). Duration of sleep bordered a medium effect for cognitive symptoms (ηp2=.05) and was in the medium range for PTSD and depressive symptoms (ηp2=.06). Although deployment-related mild TBI history was significant in all models, effect sizes were small (ηp2=.01). Findings from the present study provide support that health behaviors have stronger effects with regard to cognitive, PTSD, and depressive symptoms compared to deployment-related mild TBI history in military personnel and, given their modifiable nature, may represent treatment targets in this population.

Therapeutic Relationship in mTBI Rehabilitation: The Disparity Between the Illness Experience and Clinical Definitions

INTRODUCTION

A positive therapeutic relationship is characterized by trust and mutually perceived genuineness. It is positively associated with patients' adherence to treatment, satisfaction, and health outcomes. When service members with a history of mild traumatic brain injury (mTBI) present to rehabilitation clinics with nonspecific symptoms, a disparity between their experience of disability and clinical expectations of mTBI may disrupt the establishment of a positive therapeutic relationship between patients and providers. The objectives of this study are to (1) explore disparities between military service members and rehabilitation clinicians about the clinical diagnosis and illness experience of mTBI and (2) identify barriers to the establishment of a positive therapeutic relationship.

MATERIALS AND METHODS

This is a qualitative descriptive study of military service members with prior mTBI (n = 18) and clinicians (n = 16) who participated in interviews and focus groups. Data were analyzed thematically using Kleinman's framing of illness experience and clinical diagnosis.

RESULTS

Three themes reflected the potential breakdowns in the therapeutic relationship. The first theme, clinical expectations for post-injury recovery versus patients' experience of ongoing disability, reflects the inconsistency between clinicians' expectations of symptom resolution within 90 days following mTBI and service members' experiences of symptoms that worsened over several months or years. The second theme, symptom attribution to mental health conditions versus tissue injury, describes the difficulty in attributing symptoms to the physical impact of the mTBI or mental health diagnoses that may also stem from the injury event. The third theme, suspected malingering versus valid disability, describes clinicians' reports of frustration with cases in which they suspected malingering for secondary gains in contrast with service members' feelings that their problems were not taken seriously by clinicians.

CONCLUSIONS

This study extended previous research on therapeutic relationships by examining the situation of mTBI rehabilitation services for military service members. The findings reinforce the best practice recommendations of acknowledging patients' experiences, addressing the presenting symptoms and problems, and encouraging progressive return to activity following mTBI. Acknowledgment of and attention to patients' illness experience by rehabilitation clinicians is necessary and important for supporting a positive therapeutic relationship and ultimately to optimize patients' health outcomes and reduce disability.

Prognostic factors for persistent symptoms in adults with mild traumatic brain injury: an overview of systematic reviews

BACKGROUND

Mild traumatic brain injury (mTBI) is an increasing public health problem, because of its persistent symptoms and several functional consequences. Understanding the prognosis of a condition is an important component of clinical decision-making and can help to guide the prevention of persistent symptoms following mTBI. The prognosis of mTBI has stimulated several empirical primary research papers and many systematic reviews leading to the identification of a wide range of factors. We aim to synthesize these factors to get a better understanding of their breadth and scope.

METHODS

We conducted an overview of systematic reviews. We searched in databases systematic reviews synthesizing evidence about the prognosis of persistent symptoms after mTBI in the adult population. Two reviewers independently screened all references and selected eligible reviews based on eligibility criteria. They extracted relevant information using an extraction grid. They also rated independently the risk of bias using the ROBIS tool. We synthesized evidence into a comprehensive conceptual map to facilitate the understanding of prognostic factors that have an impact on persistent post-concussion symptoms.

RESULTS

From the 3857 references retrieved in a database search, we included 25 systematic reviews integrating the results of 312 primary articles published between 1957 and 2019. We examined 35 prognostic factors from the systematics reviews. No single prognostic factor demonstrated convincing and conclusive results. However, age, sex, and multiple concussions showed an affirmatory association with persistent post-concussion outcomes in systematic reviews.

CONCLUSION

We highlighted the need for a comprehensive picture of prognostic factors related to persistent post-concussion symptoms. We believe that these prognostic factors would guide clinical decisions and research related to prevention and intervention regarding persistent post-concussion symptoms.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020176676.

Study protocol for investigating the clinical performance of an automated blood test for glial fibrillary acidic protein and ubiquitin carboxy-terminal hydrolase L1 blood concentrations in elderly patients with mild traumatic BRAIN Injury and reference values (BRAINI-2 Elderly European study): a prospective multicentre observational study

INTRODUCTION

Two blood brain-derived biomarkers, glial fibrillar acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), can rule out intracranial lesions in patients with mild traumatic brain injury (mTBI) when assessed within the first 12 hours. Most elderly patients were excluded from previous studies due to comorbidities. Biomarker use in elderly population could be affected by increased basal levels. This study will assess the performance of an automated test for measuring serum GFAP and UCH-L1 in elderly patients to predict the absence of intracranial lesions on head CT scans after mTBI, and determine both biomarkers reference values in a non-TBI elderly population.

METHODS AND ANALYSIS

This is a prospective multicentre observational study on elderly patients (≥65 years) that will be performed in Spain, France and Germany. Two patient groups will be included in two independent substudies. (1) A cohort of 2370 elderly patients (1185<80 years and 1185≥80 years; BRAINI2-ELDERLY DIAGNOSTIC AND PROGNOSTIC STUDY) with mTBI and a brain CT scan that will undergo blood sampling within 12 hours after mTBI. The primary outcome measure is the diagnostic performance of GFAP and UCH-L1 measured using an automated assay for discriminating between patients with positive and negative findings on brain CT scans. Secondary outcome measures include the performance of both biomarkers in predicting early (1 week) and midterm (3 months) neurological status and quality of life after trauma. (2) A cohort of 480 elderly reference participants (BRAINI2-ELDERLY REFERENCE STUDY) in whom reference values for GFAP and UCHL1 will be determined.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Review Boards of Hospital 12 de Octubre in Spain (Re#22/027) and Southeast VI (Clermont Ferrand Hospital) (Re# 22.01782.000095) in France. The study's results will be presented at scientific meetings and published in peer-review publications.

TRIAL REGISTRATION NUMBER

NCT05425251.

Mild Traumatic Brain Injury and Functional Outcome in Older Adults: Pain Interference But Not Cognition Mediates the Relationship Between Traumatic Injury and Functional Difficulties

OBJECTIVE

To examine functional status of older people 3 months after mild traumatic brain injury (mTBI) and identify whether pain interference or cognition mediates any relationship found between injury status and functional outcomes.

SETTING

Patients admitted to a Melbourne-based emergency department.

PARTICIPANTS

Older adults 65 years and older: 40 with mTBI, 66 with orthopedic injury without mTBI (TC), and 47 healthy controls (CC) without injury.

DESIGN

Observational cohort study.

MAIN MEASURES

Functional outcome was measured using the World Health Organization Disability Assessment Schedule (WHODAS 2.0) and single- and dual-task conditions of the Timed-Up-and-Go task. Pain interference and cognitive performance at 3 months post-injury were examined as mediators of the relationship between injury status (injured vs noninjured) and functional outcome.

RESULTS

Patients with mTBI and/or orthopedic injury reported greater difficulties in overall functioning, including community participation, compared with noninjured older people (CC group). Both trauma groups walked slower than the CC group on the mobility task, but all groups were similar on the dual-task condition. Pain interference mediated the relationship between injury status and overall functioning [ b = 0.284; 95% CI = 0.057, 0.536), community participation ( b = 0.259; 95% CI = 0.051, 0.485), and mobility ( b = 0.116; 95% CI = 0.019, 0.247). However, cognition did not mediate the relationship between injury status and functional outcomes.

CONCLUSIONS

Three months after mild traumatic injury (with and without mTBI), patients 65 years and older had greater functional difficulties compared with noninjured peers. Pain interference, but not cognition, partially explained the impact of traumatic injury on functional outcomes. This highlights the importance of reducing pain interference for older patients after injury (including mTBI) to support better functional recovery.

Salivary Cortisol Dynamics After Mild Traumatic Brain Injury

OBJECTIVE

To assess mild traumatic brain injury (mTBI)-related alterations in baseline (resting) salivary cortisol and cortisol reactivity to cognitive and exercise stressors, which are frequently encountered during mTBI rehabilitation and recovery.

SETTING

Persons with mTBI were recruited from a level 1 trauma center emergency department. Uninjured controls (UCs) were recruited from the community.

PARTICIPANTS

Participants were 37 individuals with mTBI and 24 UCs. All patients with mTBI were enrolled at 7 ± 3 days post-injury, met the American Congress of Rehabilitation Medicine definition of mTBI, and had no acute intracranial findings on clinical neuroimaging (if performed).

DESIGN

A prospective cohort study design was used. All participants provided saliva samples 10 times during each of 2 visits spaced 3 weeks apart (1 week and 1 month post-injury for the mTBI group). Each visit included baseline saliva sampling and sampling to evaluate reactivity to a cognitive stressor (Paced Auditory Serial Addition Test) and physical stressor (Buffalo Concussion Treadmill Test [BCTT]).

MAIN OUTCOME MEASURE

Natural log-transformed salivary cortisol was measured by enzyme immunoassay. Cortisol was predicted using a linear mixed-effects model by group (mTBI and UC), visit (1 week and 1 month), and saliva sample.

RESULTS

Mean salivary cortisol was higher in the mTBI group (1.67 nmol/L [95% CI 1.42-1.72]) than in controls (1.30 nmol/L [1.12-1.47]), without an mTBI × time interaction. At 1 week, the mTBI group had greater cortisol reactivity in response to the BCTT.

CONCLUSIONS

Higher cortisol in individuals with mTBI at 1 week and 1 month post-injury extends previous findings into the subacute recovery period. Furthermore, the mTBI group demonstrated a greater cortisol response to mild-to-moderate aerobic exercise (BCTT) at 1 week post-injury. Given the increasing role of exercise in mTBI rehabilitation, further research is warranted to replicate these findings and identify the clinical implications, if any, of enhanced hypothalamic-pituitary-adrenal axis responses to exercise in civilians with recent mTBI.

Potential Biomarkers in Experimental Animal Models for Traumatic Brain Injury

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

Identifying prioritization criteria for patients with mtbi waiting for multidisciplinary rehabilitation services: A Delphi study

INTRODUCTION

Rehabilitation service providers must take into account prognostic factors when making clinical decisions, which includes using these factors as prioritization criteria. The goal of this study was to establish consensus on patient prioritization criteria based on prognostic factors related to persistent symptoms for patients with mild traumatic brain injury (mTBI) waiting for outpatient specialized rehabilitation services.

MATERIALS AND METHODS

We conducted a Delphi survey involving clinicians, researchers, decision makers, and patients. Before the survey, we presented the results of an overview of systematic reviews summarizing the evidence on prognostic factors related to post-concussion symptoms.

RESULTS

After two rounds, the 17 experts reached consensus on the inclusion of 12 prioritization criteria: acute stress disorder, anxiety and depression, baseline mental and physical health, functional impacts and difficulties in performing daily habits after the trauma, motivation to receive services, multiple concussions, prior neurological problems, PTSD, quality of sleep, return to work failures, somatic complaints, suicidal ideation.

CONCLUSION

Healthcare stakeholders must consider a wide range of factors to guide clinical decision-making, including about access to care and patient prioritization. This study shows that the Delphi technique can be used to reach consensus on such decisions regarding patients with mTBI who are waiting for outpatient specialized rehabilitation services.

Intrathecal dexmedetomidine attenuates mechanical allodynia through the downregulation of brain-derived neurotrophic factor in a mild traumatic brain injury rat model

BACKGROUND

This study evaluated the effects of dexmedetomidine and propofol on brain-derived neurotrophic factor level in the cerebrospinal fluid (c-BDNF) and mechanical allodynia in a mild traumatic brain injury (TBI) rat model.

METHODS

After fixing the rat's skull on a stereotactic frame under general anesthesia, craniotomy was performed. After impact, 10 µl of drug was injected into the cisterna magna (group S: sham, group D: dexmedetomidine 5 μg/kg, group P: propofol 500 μg/kg, and group T: untreated TBI). The 50% mechanical withdrawal threshold (50% MWT) and c-BDNF level were measured on postoperative days (PODs) 1, 7, and 14.

RESULTS

The 50% MWT measured on PODs 1, 7, and 14 was lower and the c-BDNF level on POD 1 was higher in group T than in group S. In group D, the c-BDNF level on POD 1 was lower than that in group T and was comparable with that in group S during the whole study period. The 50% MWT of group D was higher than that of group T throughout the postoperative period. In group P, there were no significant differences in the 50% MWT during the entire postoperative period compared with group T; the c-BDNF level was higher than that in group T on POD 1.

CONCLUSIONS

Intrathecal administration of dexmedetomidine may attenuate TBI-induced mechanical allodynia for up to two weeks post-injury through immediate suppression of c-BDNF in mild TBI rats. The inhibition of c-BDNF expression in the acute phase reduced the occurrence of TBI-induced chronic neuropathic pain.

Reorganized Hubs of Brain Functional Networks after Acute Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI)-associated damage to hub regions can lead to disrupted modular structures of functional brain networks and may result in widespread cognitive and behavioral deficits. The spatial layout of brain connections and modules is essential for understanding the reorganization of brain networks to trauma. We investigated the roles of hubs in inter-subnetwork information coordination and integration using participation coefficients (PCs) in 74 patients with acute mTBI and 51 matched healthy controls. In some brain networks, such as default mode network (DMN) and frontoparietal network (FPN), mild TBI patients had decreased PC levels, while this measure was saliently increased in patients in other networks, such as the visual network. The hub disruption index was defined as the gradient of a straight line fitted to scatterplots of individual mTBI in participation coefficient versus mean participation coefficient of healthy groups. There was a trend of radical reorganization of some efficient "hub" nodes in patients (κ = -0.15), compared with controls (κ close to 0). The PC of brain hubs can also differentiate mTBI patients from controls with an 88% accuracy, and decreased PC levels in FPN can predict patient' s worse cognitive information processing speed (r = 0.36, p < 0.002) and working memory performance (r = 0.35, p < 0.002). Reduced PC within the DMN was associated with patients' complaints of post-concussion symptoms (r = -0.35, p < 0.002). This evidence suggests a trend of spatial transition of hub profiles in acute mTBI, and graph metrics of PC measures can be used as potential diagnostic biomarkers.

Involvement of Lateral Habenula Dysfunction in Repetitive Mild Traumatic Brain Injury-Induced Motivational Deficits

Affective disorders including depression (characterized by reduced motivation, social withdrawal, and anhedonia), anxiety, and irritability are frequently reported as long-term consequences of mild traumatic brain injury (mTBI) in addition to cognitive deficits, suggesting a possible dysregulation within mood/motivational neural circuits. One of the important brain regions that control motivation and mood is the lateral habenula (LHb), whose hyperactivity is associated with depression. Here, we used a repetitive closed-head injury mTBI model that is associated with social deficits in adult male mice and explored the possible long-term alterations in LHb activity and motivated behavior 10-18 days post-injury. We found that mTBI increased the proportion of spontaneous tonically active LHb neurons yet decreased the proportion of LHb neurons displaying bursting activity. Additionally, mTBI diminished spontaneous glutamatergic and GABAergic synaptic activity onto LHb neurons, while synaptic excitation and inhibition (E/I) balance was shifted toward excitation through a greater suppression of GABAergic transmission. Behaviorally, mTBI increased the latency in grooming behavior in the sucrose splash test suggesting reduced self-care motivated behavior following mTBI. To show whether limiting LHb hyperactivity could restore motivational deficits in grooming behavior, we then tested the effects of Gi (hM4Di)-DREADD-mediated inhibition of LHb activity in the sucrose splash test. We found that chemogenetic inhibition of LHb glutamatergic neurons was sufficient to reverse mTBI-induced delays in grooming behavior. Overall, our study provides the first evidence for persistent LHb neuronal dysfunction due to an altered synaptic integration as causal neural correlates of dysregulated motivational states by mTBI.

Symptoms of major depressive disorder and post-traumatic stress disorder in veterans with mild traumatic brain injury: A network analysis

Mild Traumatic Brain Injury (mTBI, or concussion) is a debilitating condition that often leads to persistent cognitive and mental health problems post-injury. Post-traumatic Stress Disorder (PTSD) and Major Depressive Disorder (MDD) are two most commonly occurring mental health problems following mTBI and are suggested to be strong contributors to the persistent post-concussion symptoms. Thus, it is important to understand the symptomatology of PTSD and MDD post-mTBI, to better inform targets for behavioral health interventions. Therefore, the current study examined the symptom structure of post-mTBI co-morbid PTSD and MDD through network approaches; we compared the network structure of participants with a positive mTBI screen (N = 753) to the network structure of participants with a negative mTBI screen (N = 2044); lastly, we examined a network of PTSD and MDD symptoms with clinical covariates in a positive mTBI sample. We found that feeling distant/cutoff (P10) and difficulty concentrating (P15) were the most central symptoms in the positive mTBI network and sleep problems were the most prominent bridge nodes across the disorders. No significant difference between the positive and negative mTBI network were found through network comparison tests. Moreover, anxiety and insomnia were strongly associated with sleep symptoms and irritability symptoms, and emotional support and resilience were potential buffers against most of the PTSD and MDD symptoms. The results of this study might be particularly useful for identifying targets (i.e., feeling distant, concentration and sleep problems) for screening, monitoring and treatment after concussion to better inform post-mTBI mental health care and to improve treatment outcomes.

Sports-related concussion: assessing the comprehension, collaboration, and contribution of chiropractors

Over the last 2 decades, sports-related concussion (SRC) awareness and management have evolved from an emphasis on complete cognitive and physical rest to evidence-based protocols and interventions. Chiropractors are primary care providers with exposure to athletes and teams in collision sports and, in addition, manage patients with concussion-like symptoms including neck pain, dizziness, and headache. With SRC frequently occurring in the absence of a medical practitioner, the role of allied health practitioners like chiropractors should be emphasised when it comes to the recognition, assessment, and management of SRC. This commentary discusses the potential contribution of chiropractors in SRC and the specific role their expertise in the cervical spine may play in symptom evaluation and management. A PubMed and Google scholar review of the chiropractic SRC literature suggests that the chiropractic profession appears under-represented in concussion research in athletic populations compared to other medical and allied health fields. This includes an absence of chiropractic clinicians with a focus on SRC participating in the Concussion in Sport Group (CISG) and the International Consensus Conferences on Concussion. Furthermore, with evolving evidence suggesting the importance of cervicogenic manifestations in SRC, there is an opportunity for chiropractors to participate in SRC diagnosis and management more fully and contribute scientifically to an area of specialised knowledge and training. With a dearth of chiropractic orientated SRC science, clinical SRC expertise, and clinical chiropractic representation in the CISG; it is incumbent on chiropractic clinicians and scientists to take up this opportunity through meaningful contribution and involvement in the SRC field.

Development of an MMPI reference group for outpatients with persisting symptoms following mild TBI

OBJECTIVE

To develop an MMPI-2-RF reference group for persistently symptomatic patients with mTBI in order to aid interpretation and better evaluate atypical scale elevations.

METHOD

Using the Q Local MMPI-2-RF Comparison Group Generator (CGG), 200 valid MMPI-2-RF profiles were aggregated for mTBI outpatients with persisting symptoms 2-24 months post injury.

RESULTS

Compared to established MMPI general population norms, individuals with persisting symptoms demonstrated elevations on several scales, primarily in cognitive and somatic domains. T scores > 60 and standard deviations > 10 were observed for the F-r (Infrequent Responses), Fs (Infrequent Somatic Responses), FBS-r (Symptom Validity), RBS (Response Bias Scale), RC1 (Somatic Complaints), MLS (Malaise), HPC (Head Pain Complaints), NUC (Neurological Complaints), and COG (Cognitive Complaints) scales. All other scales were consistent with established norms for the general population.

CONCLUSION

This study is the first to establish an empirically derived MMPI reference group for individuals with persisting symptoms following mTBI. By comparing MMPI profiles of patients with mTBI against this reference group, clinicians may be better able to identify abnormal symptomatology. Evaluating profiles within this context may allow for more accurate case conceptualization and targeted treatment recommendations for those patients who demonstrate disproportionate symptomatology outside the range of the mTBI reference group.

The impact of prior head injury on outcomes following group and individual cognitive processing therapy among military personnel

This study examined the impact of a history of head injury (HHI) on posttraumatic stress disorder (PTSD) and depression symptoms in active duty military personnel following group and individual cognitive processing therapy (CPT). Data for these secondary analyses were drawn from a clinical trial comparing group and individual CPT. Service members (N = 268, 91.0% male) were randomized to 12 sessions of group (n = 133) or individual (n = 135) CPT. Most participants (57.1%) endorsed a deployment-related HHI, 92.8% of whom reported currently experiencing symptoms (CES) related to the head injury (i.e., HHI/CES). Patients classified as non-HHI/CES demonstrated large, significant improvements in PTSD symptom severity in both individual and group therapy, ds = 1.1, p < .001. Patients with HHI/CES status showed similar significant improvements when randomized to individual CPT, d = 1.4, p < .001, but did not demonstrate significant improvements when randomized to group CPT, d = 0.4, p = .060. For participants classified as HHI/CES, individual CPT was significantly superior to group CPT, d = 0.98, p = .003. Symptoms of depression improved following treatment, with no significant differences by treatment delivery format or HHI/CES status. The findings of this clinical trial subgroup study demonstrate evidence that group CPT is less effective than individual CPT for service members classified as HHI/CES. The results suggest that HHI/CES status may be important to consider in selecting patients for group or individual CPT; additional research is needed to confirm the clinical implications of these findings.

TBI and risk of death in military veterans over 14 years: Injury severity, timing, and cause of death

The objective of this study was to determine the association of traumatic brain injury (TBI) with mortality in military veterans and whether this association differs as a function of TBI severity, timing, and cause of death. This national cohort study used U.S. Department of Veterans Affairs' (VA) data of patients 18 years and older with TBI diagnoses (N = 213,290) and 1:1 propensity-matched comparison random sample of patients without TBI (N = 213,290). The main outcome measure was mortality within 6 months of TBI diagnosis and longer-term (after 6 months). Cox proportional hazards models were used to examine risk of all-cause mortality according to TBI severity and Fine-Gray proportional hazards regression to examine time to cause-specific mortality, accounting for competing risk of other deaths. For patients with moderate-to-severe TBI (compared with no TBI), hazard ratios (HRs) for mortality were highest within first 6 months of injury (fully-adjusted HR: 2.42, 95% CI: 2.32-2.53); for mild TBIs, HRs for mortality were lower and relatively constant over time (fully-adjusted HR within first 6 months: 1.33, 95% CI: 1.26-1.39). Veterans with mild and moderate-to-severe TBI had higher risk of future death over short term for 9 out 10 of the U.S. leading causes of death, with only unintentional injury, stroke, and suicide showing differences by TBI severity. Associations attenuated significantly from within to after 6 months TBI diagnosis. These findings indicate that adults with TBI are at increased risk of majority of leading causes of death, with differential risk by TBI severity and timing of death.

"I Don't Think It's on Anyone's Radar": The Workforce and System Barriers to Healthcare for Indigenous Women Following a Traumatic Brain Injury Acquired through Violence in Remote Australia

Aboriginal and Torres Strait Islander women experience high rates of traumatic brain injury (TBI) as a result of violence. While healthcare access is critical for women who have experienced a TBI as it can support pre-screening, comprehensive diagnostic assessment, and referral pathways, little is known about the barriers for Aboriginal and Torres Strait Islander women in remote areas to access healthcare. To address this gap, this study focuses on the workforce barriers in one remote region in Australia. Semi-structured interviews and focus groups were conducted with 38 professionals from various sectors including health, crisis accommodation and support, disability, family violence, and legal services. Interviews and focus groups were audiotaped and transcribed verbatim and were analysed using thematic analysis. The results highlighted various workforce barriers that affected pre-screening and diagnostic assessment including limited access to specialist neuropsychology services and stable remote primary healthcare professionals with remote expertise. There were also low levels of TBI training and knowledge among community-based professionals. The addition of pre-screening questions together with professional training on TBI may improve how remote service systems respond to women with potential TBI. Further research to understand the perspectives of Aboriginal and Torres Strait Islander women living with TBI is needed.

Acute serum free thiols: a potentially modifiable biomarker of oxidative stress following traumatic brain injury

Serum concentrations of free thiols (key components of the extracellular antioxidant machinery) reflect the overall redox status of the human body. The objective of this exploratory study was to determine the concentrations of serum free thiols in the acute phase after traumatic brain injury (TBI) and their association with long-term outcome. In this observational cohort study, patients with TBI of various severity were included from a biobank of prospectively enrolled TBI patients. Further eligibility criteria included an available blood sample and head computed tomography data, obtained within 24 h of injury, as well as a functional outcome assessment (Glasgow Outcome Scale Extended (GOSE)) at 6 months post-injury. Serum free thiol concentrations were markedly lower in patients with TBI (n = 77) compared to healthy controls (n = 55) (mean ± standard deviation; 210.3 ± 63.3 vs. 301.8 ± 23.9 μM, P < 0.001) indicating increased oxidative stress. Concentrations of serum free thiols were higher in patients with complete functional recovery (GOSE = 8) than in patients with incomplete recovery (GOSE < 8) (median [interquartile range]; 235.7 [205.1-271.9] vs. 205.2 [173-226.7] μM, P = 0.016), suggesting that patients with good recovery experience less oxidative stress in the acute phase after TBI or have better redox function. Acute TBI is accompanied by a markedly lower concentration of serum free thiols compared to healthy controls indicating that serum free thiols may be a novel biomarker of TBI. Future studies are warranted to validate our findings and explore the clinical applicability and prognostic capability of this candidate-biomarker.

Prevalence and Correlates of Depressive Symptoms Within 6 Months After First-Time Mild Traumatic Brain Injury

OBJECTIVE

Depressive symptoms are among the most common neuropsychiatric sequelae of mild traumatic brain injury (mTBI). Very few studies have compared correlates of depressive symptoms within the first 6 months of injury in cohorts experiencing their first TBI. The authors investigated whether the correlates of depressive symptoms (being female, older, lower education, having brain lesions, experiencing worse postconcussive symptoms, and incomplete functional recovery) that have been established in populations with moderate to severe TBI were the same for individuals with first-time mTBI within the first 6 months of recovery.

METHODS

Two hundred seventeen individuals with first-time mTBI were divided into subgroups-new-onset depressive symptoms, recurrent depressive symptoms, prior depression history only, and never depressed-and compared on clinical and demographic variables and the presence of postconcussive symptoms and functional recovery at 3 and 6 months.

RESULTS

New-onset depressive symptoms developed in 12% of the cohort, whereas 11% of the cohort had recurrent depressive symptoms. Both depressive symptoms groups were more likely to comprise women and persons of color and were at higher risk for clinically significant postconcussive symptoms and incomplete functional recovery for the first 6 months postinjury.

CONCLUSIONS

Presence of depressive symptoms after first-time mTBI was associated with persistent postconcussive symptoms and incomplete functional recovery in the first 6 months. Adding to the existing literature, these findings identified correlates of depressive symptom development and poor outcomes after mTBI, thus providing further evidence that mTBI may produce persistent symptoms and functional limitations that warrant clinical attention.

Diffusion Tensor Imaging Reveals Elevated Diffusivity of White Matter Microstructure that Is Independently Associated with Long-Term Outcome after Mild Traumatic Brain Injury: A TRACK-TBI Study

Diffusion tensor imaging (DTI) literature on single-center studies contains conflicting results regarding acute effects of mild traumatic brain injury (mTBI) on white matter (WM) microstructure and the prognostic significance. This larger-scale multi-center DTI study aimed to determine how acute mTBI affects WM microstructure over time and how early WM changes affect long-term outcome. From Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI), a cohort study at 11 United States level 1 trauma centers, a total of 391 patients with acute mTBI ages 17 to 60 years were included and studied at two weeks and six months post-injury. Demographically matched friends or family of the participants were the control group (n = 148). Axial diffusivity (AD), fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) were the measures of WM microstructure. The primary outcome was the Glasgow Outcome Scale Extended (GOSE) score of injury-related functional limitations across broad life domains at six months post-injury. The AD, MD, and RD were higher and FA was lower in mTBI versus friend control (FC) at both two weeks and six months post-injury throughout most major WM tracts of the cerebral hemispheres. In the mTBI group, AD and, to a lesser extent, MD decreased in WM from two weeks to six months post-injury. At two weeks post-injury, global WM AD and MD were both independently associated with six-month incomplete recovery (GOSE <8 vs = 8) even after accounting for demographic, clinical, and other imaging factors. DTI provides reliable imaging biomarkers of dynamic WM microstructural changes after mTBI that have utility for patient selection and treatment response in clinical trials. Continued technological advances in the sensitivity, specificity, and precision of diffusion magnetic resonance imaging hold promise for routine clinical application in mTBI.

Post-Concussion Symptoms Rule: Derivation and Validation of a Clinical Decision Rule for Early Prediction of Persistent Symptoms after a Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is a common problem. Depending on diagnostic criteria, 13 to 62% of those patients develop persistent post-concussion symptoms (PPCS). The main objective of this prospective multi-center study is to derive and validate a clinical decision rule (CDR) for the early prediction of PPCS. Patients aged ≥14 years were included if they presented to one of our seven participating emergency departments (EDs) within 24 h of an mTBI. Clinical data were collected in the ED, and symptom evolution was assessed at 7, 30 and 90 days post-injury using the Rivermead Post-Concussion Questionnaire (RPQ). The primary outcome was PPCS at 90 days after mTBI. A predictive model called the Post-Concussion Symptoms Rule (PoCS Rule) was developed using the methodological standards for CDR. Of the 1083 analyzed patients (471 and 612 for the derivation and validation cohorts, respectively), 15.6% had PPCS. The final model included the following factors assessed in the ED: age, sex, history of prior TBI or mental health disorder, headache in ED, cervical sprain and hemorrhage on computed tomography. The 7-day follow-up identified additional risk factors: headaches, sleep disturbance, fatigue, sensitivity to light, and RPQ ≥21. The PoCS Rule had a sensitivity of 91.4% and 89.6%, a specificity of 53.8% and 44.7% and a negative predictive value of 97.2% and 95.8% in the derivation and validation cohorts, respectively. The PoCS Rule will help emergency physicians quickly stratify the risk of PPCS in mTBI patients and better plan post-discharge resources.

A consensus on optimization of care in patients with growth hormone deficiency and mild traumatic brain injury

OBJECTIVE/DESIGN

Approximately 2.9 million children and adults in the US experience traumatic brain injuries (TBIs) annually, most of which are considered mild. TBI can induce varying consequences on pituitary function, with growth hormone deficiency (GHD) among the more commonly reported conditions. Panels of pediatric and adult endocrinologists, neurologists, physical medicine and rehabilitation specialists, and neuropsychologists convened in February and October 2020 to discuss ongoing challenges and provide strategies for detection and optimal management of patients with mild TBI and GHD.

RESULTS

Difficulties include a low rate of seeking medical attention in the population, suboptimal screening tools, cost and complexity of GHD testing, and a lack of consensus regarding when to test or retest for GHD. Additionally, referrals to endocrinologists from other specialists are uncommon. Recommendations from the panels for managing such patients included multidisciplinary guidelines on the diagnosis and management of post-TBI GHD and additional education on long-term metabolic and probable cognitive benefits of GH replacement therapy.

CONCLUSION

As patients of all ages with mild TBI may develop GHD and/or other pituitary deficiencies, a multidisciplinary approach to provide education to endocrinologists, neurologists, neurosurgeons, traumatologists, and other providers and guidelines for the early identification and management of persistent mild TBI-related GHD are urgently needed.

The S-100B level, intracranial pressure, body temperature, and transcranial blood flow velocities predict the outcome of the treatment of severe brain injury

This study evaluates the applicability of S100B levels, mean maximum velocity (Vmean) over time, pulsatility index (PI), intracranial pressure (ICP), and body temperature (T) for the prediction of the treatment of patients with traumatic brain injury (TBI). Sixty patients defined by the Glasgow Coma Scale score ≤ 8 were stratified using the Glasgow Coma Scale into 2 groups: favorable (FG: Glasgow Outcome Scale ≥ 4) and unfavorable (UG: Glasgow Outcome Scale < 4). The S100B concentration was at the time of hospital admission. Vmean was measured using transcranial Doppler. PI was derived from a transcranial Doppler examination. T was measured in the temporal artery. The differences in mean between FG and UG were tested using a bootstrap test of 10,000 repetitions with replacement. Changes in S100B, Vmean, PI, ICP, and T levels stratified by the group were calculated using the one-way aligned rank transform for nonparametric factorial analysis of variance. The reference ranges for the levels of S100B, Vmean, and PI were 0.05 to 0.23 µg/L, 30.8 to 73.17 cm/s, and 0.62 to 1.13, respectively. Both groups were defined by an increase in Vmean, a decrease in S100B, PI, and ICP levels; and a virtually constant T. The unfavorable outcome is defined by significantly higher levels of all parameters, except T. A favorable outcome is defined by S100B < 3 mg/L, PI < 2.86, ICP > 25 mm Hg, and Vmean > 40 cm/s. The relationships provided may serve as indicators of the results of the TBI treatment.

Cognitive performance in older people after mild traumatic brain injury: Trauma effects and other risk factors

OBJECTIVE

Cognitive symptoms are common in the initial weeks after mTBI, but recovery is generally expected within three months. However, there is limited information about recovery specifically in older age cohorts. Therefore, this study investigated cognitive outcome three months after mTBI in older adults (≥ 65 years) compared to trauma and community age-matched controls and explored risk factors for outcome after traumatic injury.

METHODS

Older mTBI patients (n = 40) and older adults with mild traumatic injury but without head injury (n = 66) were compared to a noninjured community control group (n = 47). Cognitive assessment included neuropsychological and computerized tests. Group differences were compared on individual tasks and overall cognitive performances using composite scores. Regression analyses identified predictors of outcome for trauma patients and moderator analyses explored possible interactions of mTBI severity with age and cognition.

RESULTS

As well as lower performances in processing speed and memory, both trauma groups had significantly lower performance on composite neuropsychological (d = .557 and .670) and computerized tasks (d = .783 and .824) compared to noninjured controls. Age, education, and history of depression were direct predictors of cognitive performance after mild traumatic injury (with or without head injury). Further moderation analysis demonstrated that mTBI severity (Glasgow Coma Scale < 15) moderated the impact of older age on computerized assessment (β = -.138).

CONCLUSIONS

Three months after mild trauma (regardless of head injury), older people demonstrate lower cognition compared to noninjured peers. However, severity of mTBI (Glasgow Coma Scale < 15) can interact with older age to predict poorer cognitive outcomes.

Head Trauma in a Community-Based Sample of Victims of Intimate Partner Violence: Prevalence, Mechanisms of Injury and Symptom Presentation

OBJECTIVE

The present study aimed to explore the prevalence of subconcussive head trauma, traumatic brain injury (TBI), potential hypoxic events, and hypoxic brain injury (HBI) in victims of physical intimate partner violence (IPV). The study also aimed to characterize the injury presentation and mechanisms of injury in this population.

METHOD

A group of 47 female participants with a history of at least one relationship that included physical violence completed a structured interview assessing for subconcussive hits, TBI, and HBI. Participants ranged in age from 19 to 55, and had an average of 15.3 years of education. Forty-four participants completed the structured interview in person and three participants completed the interview over the phone.

RESULTS

The majority of participants reported sustaining at least one impact to the head and approximately half of the participants sustained at least one impact that resulted in a mild TBI. Approximately half of the participants experienced at least one incident of having difficulty breathing due to a violent act from their partner, and approximately one-third of participants reported symptoms consistent with mild HBI. The most common mechanisms of injury were being hit with a closed fist and being strangled.

CONCLUSIONS

The high levels of head trauma observed in this study highlight the need for clinical and community providers to screen victims of physical IPV for head trauma. The unique characteristics of this population (female sex, high frequency of injuries, and presence of HBIs) indicate that research evaluating the cognitive effects of injuries in this population is needed.