Cognitive Impairment Following Acute Mild Traumatic Brain Injury

Nanocarrier-mediated siRNA delivery: a new approach for the treatment of traumatic brain injury-related Alzheimer's disease

Traumatic brain injury and Alzheimer's disease share pathological similarities, including neuronal loss, amyloid-β deposition, tau hyperphosphorylation, blood-brain barrier dysfunction, neuroinflammation, and cognitive deficits. Furthermore, traumatic brain injury can exacerbate Alzheimer's disease-like pathologies, potentially leading to the development of Alzheimer's disease. Nanocarriers offer a potential solution by facilitating the delivery of small interfering RNAs across the blood-brain barrier for the targeted silencing of key pathological genes implicated in traumatic brain injury and Alzheimer's disease. Unlike traditional approaches to neuroregeneration, this is a molecular-targeted strategy, thus avoiding non-specific drug actions. This review focuses on the use of nanocarrier systems for the efficient and precise delivery of siRNAs, discussing the advantages, challenges, and future directions. In principle, siRNAs have the potential to target all genes and non-targetable proteins, holding significant promise for treating various diseases. Among the various therapeutic approaches currently available for neurological diseases, siRNA gene silencing can precisely "turn off" the expression of any gene at the genetic level, thus radically inhibiting disease progression; however, a significant challenge lies in delivering siRNAs across the blood-brain barrier. Nanoparticles have received increasing attention as an innovative drug delivery tool for the treatment of brain diseases. They are considered a potential therapeutic strategy with the advantages of being able to cross the blood-brain barrier, targeted drug delivery, enhanced drug stability, and multifunctional therapy. The use of nanoparticles to deliver specific modified siRNAs to the injured brain is gradually being recognized as a feasible and effective approach. Although this strategy is still in the preclinical exploration stage, it is expected to achieve clinical translation in the future, creating a new field of molecular targeted therapy and precision medicine for the treatment of Alzheimer's disease associated with traumatic brain injury.

EEG Oscillatory Activity and Resting-State Networks Associated with Neurocognitive Function in Mild Traumatic Brain Injury

This study aimed to investigate the characteristics of resting-state electroencephalography (EEG) activity and brain networks in patients with mild traumatic brain injury (mTBI) and their association with neurocognitive function (NCF). We analyzed 26 patients with subacute mTBI and 21 healthy controls. The subacute mTBI group (9 females, 17 males) had a mean age of 29.9 ± 9.9 years, and the healthy controls (11 females, 10 males) had a mean age of 29.7 ± 11.5 years. Current source density, lagged phase synchronization, and resting-state network activity were analyzed using exact low-resolution electromagnetic tomography (eLORETA) with 60 s resting-state EEG data. In addition, a correlation analysis was performed between these EEG parameters and NCF in patients with mTBI. We used the statistical nonparametric mapping method in eLORETA to correct for multiple comparisons. There were no significant differences in EEG parameters between the patients with mTBI and healthy controls. However, in patients with mTBI, correlation analysis revealed negative correlations between theta activity in the anterior cingulate cortex and verbal short-term memory and between activity in the memory perception network and verbal memory. Our findings suggest that resting-state EEG may be clinically useful in investigating the mechanism of NCF decline in patients with mTBI.

Thriving in the wake of a storm: A systematic qualitative review & meta-synthesis on facilitating post-traumatic growth in patients living with Acquired Brain Injury

Acquired Brain Injury (ABI) often results in significant challenges, yet it may also facilitate Post-Traumatic Growth (PTG). This review explores a critical question: "What are the main factors contributing to PTG following ABI, and what potential barriers to its development are perceived by ABI survivors?" Here we aim to systematically uncover these contributors and barriers to PTG through a meta-synthesis, involving a comprehensive review of previously published qualitative research on this topic. A literature search was conducted across PsycINFO, CINAHL, and MEDLINE up to December 2022 to identify studies for inclusion. From an initial pool of 1,946 records, eleven articles were selected for inclusion. Reflexive thematic analysis yielded three analytical themes including "Journey to Self-Rediscovery", "Strength in Connection" and "Overcoming Obstacles". Our findings also revealed facilitators and barriers across multiple levels of scale including personal (e.g., acceptance versus resignation), interpersonal (e.g., positive social ties versus difficulties making social connections), and systemic (e.g., new meaning and purpose versus financial constraints) scales. Our research extends existing knowledge in ABI rehabilitation, providing a more nuanced understanding of the dynamics influencing PTG with implications for clinicians seeking to promote wellbeing following brain injury.

Dietary diversity and cognitive performance in older adults: a systematic review

BACKGROUND AND OBJECTIVE

Promoting dietary diversity (DD), which refers to the variety or the number of different food groups that people eat over the time given, is important for brain health maintenance and may be beneficial for inhibiting neurodegenerative diseases. This research aimed to review the literature and summarize research evidence for achieving an inclusive estimate concerning the relationship between DD and cognitive function in adults.

METHODS

We systematically queried the databases of PubMed, Web of Science, and Google Scholar, without imposing any date restrictions, up to June 2024 to identify original literature that sheds light on the intricate relationship between DD and cognitive function. Employing rigorous criteria, we meticulously screened studies, eliminating duplicates or those unrelated to our focus. Subsequently, we critically evaluated the findings from the selected studies, descriptively summarizing them. Additionally, we engaged in an in-depth exploration of potential mechanistic pathways linking DD to cognitive performance.

RESULTS

Of the 388 citations obtained, 23 articles were included in the final review. All the studies reported a positive association between DD score and cognitive functioning and indicated that higher DD was accompanied by good memory (n = 3) and lower risk of cognitive decline (n = 19), dementia (n = 3), and Alzheimer's disease (n = 1).

CONCLUSION

The results indicate that sustaining a diverse diet among older people may help maintain cognitive functioning. Dietary diversity represents a promising clinical avenue for mitigating cognitive decline associated with diverse brain disorders, potentially preventing or attenuating deterioration.

The effect of traumatic brain injury on learning and memory: A synaptic focus

Deficits in learning and memory are some of the most commonly reported symptoms following a traumatic brain injury (TBI). We will examine whether the neural basis of these deficits stems from alterations to bidirectional synaptic plasticity within the hippocampus. Although the CA1 subregion of the hippocampus has been a focus of TBI research, the dentate gyrus should also be given attention as it exhibits a unique ability for adult neurogenesis, a process highly susceptible to TBI-induced damage. This review examines our current understanding of how TBI results in deficits in synaptic plasticity, as well as how TBI-induced changes in endocannabinoid (eCB) systems may drive these changes. Through the synthesis and amalgamation of existing data, we propose a possible mechanism for eCB-mediated recovery in synaptic plasticity deficits. This hypothesis is based on the plausible roles of CB1 receptors in regulating inhibitory tone, influencing astrocytes and microglia, and modulating glutamate release. Dysregulation of the eCBs may be responsible for deficits in synaptic plasticity and learning following TBI. Taken together, the existing evidence indicates eCBs may contribute to TBI manifestation, pathogenesis, and recovery, but it also suggests there may be a therapeutic role for the eCB system in TBI.

Critical Review of Recently Published Studies Claiming Long-Term Neurocognitive Abnormalities in Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is the most common claimed personal injury condition for which neuropsychologists are retained as forensic experts in litigation. Therefore, it is critical that experts have accurate information when testifying as to neurocognitive outcome from concussion. Systematic reviews and six meta-analyses from 1997 to 2011 regarding objective neurocognitive outcome from mTBI provide no evidence that concussed individuals do not return to baseline by weeks to months post-injury. In the current manuscript, a critical review was conducted of 21 research studies published since the last meta-analysis in 2011 that have claimed to demonstrate long-term (i.e., ≥12 months post-injury) neurocognitive abnormalities in adults with mTBI. Using seven proposed methodological criteria for research investigating neurocognitive outcome from mTBI, no studies were found to be scientifically adequate. In particular, more than 50% of the 21 studies reporting cognitive dysfunction did not appropriately diagnose mTBI, employ prospective research designs, use standard neuropsychological tests, include appropriate control groups, provide information on motive to feign or use PVTs, or exclude, or adequately consider the impact of, comorbid conditions known to impact neurocognitive scores. We additionally analyzed 15 studies published during the same period that documented no longer term mTBI-related cognitive abnormalities, and demonstrate that they were generally more methodologically robust than the studies purporting to document cognitive dysfunction. The original meta-analytic conclusions remain the most empirically-sound evidence informing our current understanding of favorable outcomes following mTBI.

Measuring working memory span with WAIS-IV: Digit sequence is the superior span test

The Digit Span test has been part of the Wechsler tests from the first version. In the WAIS-IV the Digit Span Sequencing subtest (DSS) was introduced and in the forthcoming WAIS-5 working memory span will also be measured in the visual modality. The present study analyzes WAIS-IV Digit Span, Letter- Number Span (LNS) and WMS-III Spatial Span (SS) performance in a mixed clinical sample, expecting to find that Digit Span Forwards (DSF) lacks sensitivity to the Working Memory impairment evident in D-KEFS Trail Making Test-4 (TMT-4) scores ≤1 SD below normative means in the sample. The results showed DSF score above normative means, Digit Span Backwards (DSB) around mean, while SS and LNS was slightly impaired and DSS impaired at the same level as TMT- 4. A double dissociation was observed in DSF and SS performance between subjects with Language- and Non-verbal learning disorders. Most subjects scored in the average range on the LNS-span and high kurtosis reduced sensitivity. Taking LNS and TMT-4 as criterion measures of WM, regression analyses showed no unique contribution of DSF to the variance in these tests. The study supports prior critiques regarding the composite Digit Span measure and demonstrates that the DSS are more effective than the current version of LNS in identifying reduced Working Memory capacity.

Cluster-based analysis of PTSD-Checklist for DSM-5 (PCL-5) in civilians with post-concussive cognitive changes

OBJECTIVE

This study explores the relationship between PTSD symptoms and cognition in patients with persistent post-concussive symptoms (PPCS).

METHODS

Adults with PPCS presenting to a specialized brain injury clinic provided demographic and injury information and completed the PTSD checklist for DSM-5, Generalized Anxiety Disorder Scale-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9). The Montreal Cognitive Assessment (MoCA) was used to screen for possible cognitive concerns. Multiple regression analysis (MLR) adjusting for age, sex, mechanism of injury, psychiatric history, number of previous concussions, months since most recent injury, and mental health questionnaire scores was used to determine associations between PTSD and cognition. Binomial logistic regression explored the relationship between domains of the MoCA and PCL-5 scores.

RESULTS

We found a negative correlation between MoCA scores, PCL-5 (ρ=-0.211, p = 0.009) and PHQ-9 (ρ=-0.187, p = 0.021) in patients with PPCS and collinearity of PCL-5 and PHQ-9 scores. Significantly higher Arousal and Reactivity cluster scores within the PCL-5 were associated with poorer scores on naming and abstract tasks on the MoCA.

CONCLUSION

The association between specific PCL-5 clusters and lower MoCA scores may represent a viable target for psychotherapeutic and psychopharmacologic intervention in patients with cognitive changes associated with PPCS.

Single episode of moderate to severe traumatic brain injury leads to chronic neurological deficits and Alzheimer's-like pathological dementia

Traumatic brain injury (TBI) is one of the foremost causes of disability and mortality globally. While the scientific and medical emphasis is to save lives and avoid disability during acute period of injury, a severe health problem can manifest years after injury. For instance, TBI increases the risk of cognitive impairment in the elderly. Remote TBI history was reported to be a cause of the accelerated clinical trajectory of Alzheimer's disease-related dementia (ADRD) resulting in earlier onset of cognitive impairment and increased AD-associated pathological markers like greater amyloid deposition and cortical thinning. It is not well understood whether a single TBI event may increase the risk of dementia. Moreover, the cellular signaling pathways remain elusive for the chronic effects of TBI on cognition. We have hypothesized that a single TBI induces sustained neuroinflammation and disrupts cellular communication in a way that results later in ADRD pathology. To test this, we induced TBI in young adult CD1 mice and assessed the behavioral outcomes after 11 months followed by pathological, histological, transcriptomic, and MRI assessment. On MRI scans, these mice showed significant loss of tissue, reduced CBF, and higher white matter injury compared to sham mice. We found these brains showed progressive atrophy, markers of ADRD, sustained astrogliosis, loss of neuronal plasticity, and growth factors even after 1-year post-TBI. Because of progressive neurodegeneration, these mice had motor deficits, showed cognitive impairments, and wandered randomly in open field. We, therefore, conclude that progressive pathology after adulthood TBI leads to neurodegenerative conditions such as ADRD and impairs neuronal functions.

Involvement of Renin-Angiotensin system (RAS) components in mild traumatic brain injury

The Renin Angiotensin System (RAS) plays a pathophysiological role in traumatic brain injury (TBI) but the evidence of its involvement in mild TBI (mTBI) is still limited. We aimed at investigating the levels of components from both the classical and counter-regulatory axis of the RAS in a mTBI animal model. Mice with mTBI displayed enhanced ACE/Ang II/AT1R axis ipsilateral- and contralaterally to the trauma in the hippocampus and prefrontal cortex during acute (24 and 72 h) and later (30 days) timepoints. Increase in Ang-(1-7) levels alongside reduction in Mas receptor expression in hippocampus and prefrontal cortex was also observed after injury. Conversely, mTBI-mice presented higher expression of AT2 receptor in the contralateral hippocampus and the ipsilateral prefrontal cortex. Importantly, treatment with telmisartan, an AT1R blocker, and perindopril, an ACE inhibitor, were able to prevent mTBI-associated locomotor activity impairment and anxiety-like behavior, corroborating the involvement of RAS in the pathophysiology of mTBI. We provided original evidence that components of classical and alternative RAS axes undergo alterations in key brain areas following a mTBI in a time and hemisphere dependent manner. Our findings also open new avenues for investigating the therapeutic potential of RAS components in mTBI.

Cognitive profiles in the acute phase of traumatic brain injury according to injury severity

Although several studies have documented the chronic phase of traumatic brain injury (TBI), few verified the nature and severity of cognitive impairments during the acute phase. Among the studies carried out during the acute phase, instrumental functions were rarely examined compared to attention, memory, and executive functions. This study aimed to compare the nature and intensity of cognitive problems in the acute phase according to TBI severity and age. It was hypothesized that cognitive impairments would increase in line with TBI severity and age, and that instrumental functions would be less affected in victims of mild or moderate TBI than in those with severe TBI. The Brief Cognitive Exam in Traumatology (EXACT), a new and reliable test specifically designed and validated to briefly assess global cognitive functioning during the acute phase, was administered to 319 mild to severe TBI victims (aged 16 to 96 years), within three months post-accident. The EXACT evaluates five domains: Language, Instrumental functions (other than language), Attention and working memory, Episodic memory, and Executive functions and behavioral regulation. Results confirmed the negative influence of TBI severity and age on global cognitive functioning. Also, compared to victims with a mild or moderate TBI, a higher proportion of those with a severe TBI presented impaired instrumental functions (calculation, praxis, and gnosis). Thus, during the acute phase, the nature and severity of cognitive impairments vary according to TBI severity.

Identification and Connectomic Profiling of Concussion Using Bayesian Machine Learning

Accurate early diagnosis of concussion is useful to prevent sequelae and improve neurocognitive outcomes. Early after head impact, concussion diagnosis may be doubtful in persons whose neurological, neuroradiological, and/or neurocognitive examinations are equivocal. Such individuals can benefit from novel accurate assessments that complement clinical diagnostics. We introduce a Bayesian machine learning classifier to identify concussion through cortico-cortical connectome mapping from magnetic resonance imaging in persons with quasi-normal cognition and without neuroradiological findings. Classifier features are generated from connectivity matrices specifying the mean fractional anisotropy of white matter connections linking brain structures. Each connection's saliency to classification was quantified by training individual classifier instantiations using a single feature type. The classifier was tested on a discovery sample of 92 healthy controls (HCs; 26 females, age μ ± σ: 39.8 ± 15.5 years) and 471 adult mTBI patients (158 females, age μ ± σ: 38.4 ± 5.9 years). Results were replicated in an independent validation sample of 256 HCs (149 females, age μ ± σ: 55.3 ± 12.1 years) and 126 patients with concussion (46 females, age μ ± σ: 39.0 ± 17.7 years). Classifier accuracy exceeds 99% in both samples, suggesting robust generalizability to new samples. Notably, 13 bilateral cortico-cortical connection pairs predict diagnostic status with accuracy exceeding 99% in both discovery and validation samples. Many such connection pairs are between prefrontal cortex structures, fronto-limbic and fronto-subcortical structures, and occipito-temporal structures in the ventral ("what") visual stream. This and related connectivity form a highly salient network of brain connections that is particularly vulnerable to concussion. Because these connections are important in mediating cognitive control, memory, and attention, our findings explain the high frequency of cognitive disturbances after concussion. Our classifier was trained and validated on concussed participants with cognitive profiles very similar to those of HCs. This suggests that the classifier can complement current diagnostics by providing independent information in clinical contexts where patients have quasi-normal cognition but where concussion diagnosis stands to benefit from additional evidence.

A strike to the head: Parallels between the pediatric and adult human and the rodent in traumatic brain injury

Traumatic brain injury (TBI) is a condition that occurs commonly in children from infancy through adolescence and is a global health concern. Pediatric TBI presents with a bimodal age distribution, with very young children (0-4 years) and adolescents (15-19 years) more commonly injured. Because children's brains are still developing, there is increased vulnerability to the effects of head trauma, which results in entirely different patterns of injury than in adults. Pediatric TBI has a profound and lasting impact on a child's development and quality of life, resulting in long-lasting consequences to physical, cognitive, and emotional development. Chronic issues like learning disabilities, behavioral problems, and emotional disturbances can develop. Early intervention and ongoing support are critical for minimizing these long-term deficits. Many animal models of TBI exist, and each varies significantly, displaying different characteristics of clinical TBI. The neurodevelopment differs in the rodent from the human in timing and effect, so TBI outcomes in the juvenile rodent can thus vary from the human child. The current review compares findings from preclinical TBI work in juvenile and adult rodents to clinical TBI research in pediatric and adult humans. We focus on the four brain regions most affected by TBI: the prefrontal cortex, corpus callosum, hippocampus, and hypothalamus. Each has its unique developmental projections and thus is impacted by TBI differently. This review aims to compare the healthy neurodevelopment of these four brain regions in humans to the developmental processes in rodents.

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.

Traumatic brain injury alters the effects of class II invariant peptide (CLIP) antagonism on chronic meningeal CLIP + B cells, neuropathology, and neurobehavioral impairment in 5xFAD mice

BACKGROUND

Traumatic brain injury (TBI) is a significant risk factor for Alzheimer's disease (AD), and accumulating evidence supports a role for adaptive immune B and T cells in both TBI and AD pathogenesis. We previously identified B cell and major histocompatibility complex class II (MHCII)-associated invariant chain peptide (CLIP)-positive B cell expansion after TBI. We also showed that antagonizing CLIP binding to the antigen presenting groove of MHCII after TBI acutely reduced CLIP + splenic B cells and was neuroprotective. The current study investigated the chronic effects of antagonizing CLIP in the 5xFAD Alzheimer's mouse model, with and without TBI.

METHODS

12-week-old male wild type (WT) and 5xFAD mice were administered either CLIP antagonist peptide (CAP) or vehicle, once at 30 min after either sham or a lateral fluid percussion injury (FPI). Analyses included flow cytometric analysis of immune cells in dural meninges and spleen, histopathological analysis of the brain, magnetic resonance diffusion tensor imaging, cerebrovascular analysis, and assessment of motor and neurobehavioral function over the ensuing 6 months.

RESULTS

9-month-old 5xFAD mice had significantly more CLIP + B cells in the meninges compared to age-matched WT mice. A one-time treatment with CAP significantly reduced this population in 5xFAD mice. Importantly, CAP also improved some of the immune, histopathological, and neurobehavioral impairments in 5xFAD mice over the ensuing six months. Although FPI did not further elevate meningeal CLIP + B cells, it did negate the ability of CAP to reduce meningeal CLIP + B cells in the 5xFAD mice. FPI at 3 months of age exacerbated some aspects of AD pathology in 5xFAD mice, including further reducing hippocampal neurogenesis, increasing plaque deposition in CA3, altering microgliosis, and disrupting the cerebrovascular structure. CAP treatment after injury ameliorated some but not all of these FPI effects.

Trajectories of fatigue and related outcomes following mild acquired brain injury: a multivariate latent class growth analysis

OBJECTIVE

Fatigue is a common symptom following acquired brain injury although the severity and course differs for many individuals. This longitudinal study aimed to identify latent trajectory classes of fatigue and associated outcomes following mild brain injury.

METHODS

204 adults with mild traumatic brain injury (159; 78%) or minor stroke (45; 22%) were assessed 4 times over 1 year. Subjective measures of fatigue, anxiety, depression, cognitive complaints and societal participation were collected. Multivariate Latent Class Growth Analysis identified classes of participants with similar longitudinal patterns. Demographic and injury characteristics were used to predict class membership.

RESULTS

Analysis revealed four classes. Class 1 (53%) had mild, decreasing fatigue with no other problems. Class 2 (29%) experienced high persistent fatigue, moderate cognitive complaints and societal participation problems. Class 3 (11%) had high persistent fatigue with anxiety, depression, cognitive complaints and participation problems. Class 4 (7%) experienced decreasing fatigue with anxiety and depression but no cognitive or participation problems. Women and older individuals were more likely to be in class 2.

CONCLUSION

Half the participants had a favourable outcome while the remaining classes were characterised by persistent fatigue with cognitive complaints (class 2), decreasing fatigue with mood problems (class 4) or fatigue with both cognitive and mood problems (class 3). Fatigue treatment should target combinations of problems in such individual trajectories after mild brain injury.

Effectiveness of aerobic exercise on cognition in individuals with traumatic brain injury: A systematic review

Cognitive deficits are among the most common impairments in individuals with traumatic brain injury (TBI). Aerobic exercise is a repetitive and structured physical activity that influences structural and functional brain alterations differently. This review aims to examine the effects of aerobic exercise on cognition in individuals with TBI. PubMed, CINAHL, EMBASE, SCOPUS, MEDLINE, and Web of Science were searched from inception to December 20, 2023. Studies designed as randomized controlled trials (RCT), clinical controlled trials (CCT), and pilot studies included individuals with a confirmed diagnosis of TBI, comparing aerobic exercise with passive, active, or no control group and included at least one outcome measure assessing any cognitive domain were selected. The quality of the selected studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. Six studies met the eligibility criteria (n = 118), with 53% of participants being female. Four studies were of good quality, fair quality (n = 1), and poor quality (n = 1) on the PEDro. Two of the selected studies showed significant improvements in cognition after moderate and vigorous aerobic exercises, while four studies indicated that moderate and vigorous aerobic exercise did not improve cognition post-TBI. The evidence on the effects of moderate and vigorous aerobic exercise on cognitive function post-TBI remains limited. Additional studies are strongly warranted to understand aerobic exercise's effects on cognition post-TBI.

Compensatory cognitive training for people with traumatic brain injury: A systematic review of randomized controlled trial

Cognitive impairments are a common consequence in people with traumatic brain injury (TBI). Compensatory cognitive training is a therapeutic strategy that offers alternative methods to manage cognitive deficits. This systematic review aims to examine the effects of compensatory cognitive training on cognitive function in people with TBI. We searched PubMed, SCOPUS, MEDLINE, PEDro, Web of Science, REHABDATA, and EMBASE from inception until October 2023. The Cochrane Collaboration tool was used to assess the methodological quality of the selected studies. Of 318 articles, eight studies (n = 615), with 8% of participants being females, were included in this review. Four studies were classified as having 'high' quality according to the Cochrane Collaboration tool, while four were categorized as 'moderate' quality. There were variations in treatment protocols and outcome measures, resulting in heterogeneous findings. The effects of compensatory cognitive training on cognitive outcomes showed inconsistency. In conclusion, the evidence for the effects of compensatory cognitive training on cognition in people with TBI is promising. Further trials are needed to investigate the effects of compensatory cognitive training on various cognitive domains in people with TBI.

Weight-drop model as a valuable tool to study potential neurobiological processes underlying behavioral and cognitive changes secondary to mild traumatic brain injury

The pathophysiology of post-traumatic brain injury (TBI) behavioral and cognitive changes is not fully understood, especially in its mild presentation. We designed a weight drop TBI model in mice to investigate the role of neuroinflammation in behavioral and cognitive sequelae following mild TBI. C57BL/6 mice displayed depressive-like behavior at 72 h after mild TBI compared with controls, as indicated by a decrease in the latency to first immobility and climbing time in the forced swim test. Additionally, anxiety-like behavior and hippocampal-associated spatial learning and memory impairment were found in the elevated plus maze and in the Barnes maze, respectively. Levels of a set of inflammatory mediators and neurotrophic factors were analyzed at 6 h, 24 h, 72 h, and 30 days after injury in ipsilateral and contralateral hemispheres of the prefrontal cortex and hippocampus. Principal components analysis revealed two principal components (PC), which represented 59.1% of data variability. PC1 (cytokines and chemokines) expression varied between both hemispheres, while PC2 (neurotrophic factors) expression varied only across the investigated brain areas. Our model reproduces mild TBI-associated clinical signs and pathological features and might be a valuable tool to broaden the knowledge regarding mild TBI pathophysiology as well as to test potential therapeutic targets.

Proteomic discovery of prognostic protein biomarkers for persisting problems after mild traumatic brain injury

Some individuals with mild traumatic brain injury (mTBI), also known as concussion, have neuropsychiatric and physical problems that last longer than a few months. Symptoms following mTBI are not only impacted by the kind and severity of the injury but also by the post-injury experience and the individual's responses to it, making the persistence of mTBI particularly difficult to predict. We aimed to identify prognostic blood-based protein biomarkers predicting 6-month outcomes, in light of the clinical course after the injury, in a longitudinal mTBI cohort (N = 42). Among 420 target proteins quantified by multiple-reaction monitoring-mass spectrometry assays of blood samples, 31, 43, and 15 proteins were significantly associated with the poor recovery of neuropsychological symptoms at < 72 h, 1 week, and 1 month after the injury, respectively. Sequential associations among clinical assessments (depressive symptoms and cognitive function) affecting the 6-month outcomes were evaluated. Then, candidate biomarker proteins indirectly affecting the outcome via neuropsychological symptoms were identified. Using the identified proteins, prognostic models that can predict the 6-month outcome of mTBI were developed. These protein biomarkers established in the context of the clinical course of mTBI may have potential for clinical application.

Hippocampal interneuronal dysfunction and hyperexcitability in a porcine model of concussion

Cognitive impairment is a common symptom following mild traumatic brain injury (mTBI or concussion) and can persist for years in some individuals. Hippocampal slice preparations following closed-head, rotational acceleration injury in swine have previously demonstrated reduced axonal function and hippocampal circuitry disruption. However, electrophysiological changes in hippocampal neurons and their subtypes in a large animal mTBI model have not been examined. Using in vivo electrophysiology techniques, we examined laminar oscillatory field potentials and single unit activity in the hippocampal network 7 days post-injury in anesthetized minipigs. Concussion altered the electrophysiological properties of pyramidal cells and interneurons differently in area CA1. While the firing rate, spike width and amplitude of CA1 interneurons were significantly decreased post-mTBI, these parameters were unchanged in CA1 pyramidal neurons. In addition, CA1 pyramidal neurons in TBI animals were less entrained to hippocampal gamma (40-80 Hz) oscillations. Stimulation of the Schaffer collaterals also revealed hyperexcitability across the CA1 lamina post-mTBI. Computational simulations suggest that reported changes in interneuronal physiology may be due to alterations in voltage-gated sodium channels. These data demonstrate that a single concussion can lead to significant neuronal and circuit level changes in the hippocampus, which may contribute to cognitive dysfunction following mTBI.

Significant Acceleration of Regional Brain Aging and Atrophy After Mild Traumatic Brain Injury

Brain regions' rates of age-related volumetric change after traumatic brain injury (TBI) are unknown. Here, we quantify these rates cross-sectionally in 113 persons with recent mild TBI (mTBI), whom we compare against 3 418 healthy controls (HCs). Regional gray matter (GM) volumes were extracted from magnetic resonance images. Linear regression yielded regional brain ages and the annualized average rates of regional GM volume loss. These results were compared across groups after accounting for sex and intracranial volume. In HCs, the steepest rates of volume loss were recorded in the nucleus accumbens, amygdala, and lateral orbital sulcus. In mTBI, approximately 80% of GM structures had significantly steeper rates of annual volume loss than in HCs. The largest group differences involved the short gyri of the insula and both the long gyrus and central sulcus of the insula. No significant sex differences were found in the mTBI group, regional brain ages being the oldest in prefrontal and temporal structures. Thus, mTBI involves significantly steeper regional GM loss rates than in HCs, reflecting older-than-expected regional brain ages.

Network analysis applied to post-concussion symptoms in two mild traumatic brain injury samples

Objective

A latent disease explanation cannot exclusively explain post-concussion symptoms after mild traumatic brain injury (mTBI). Network analysis offers an alternative form of explanation for relationships between symptoms. The study aimed to apply network analysis to post-concussion symptoms in two different mTBI cohorts; an acute treatment-seeking sample and a sample 10 years post-mTBI.

Method

The treatment-seeking sample (n = 258) were on average 6 weeks post-injury; the 10 year post mTBI sample (n = 193) was derived from a population-based incidence and outcomes study (BIONIC). Network analysis was completed on post-concussion symptoms measured using the Rivermead Post-Concussion Questionnaire.

Results

In the treatment-seeking sample, frustration, blurred vision, and concentration difficulties were central to the network. These symptoms remained central in the 10 year post mTBI sample. A Network Comparison Test revealed evidence of a difference in network structure across the two samples (p = 0.045). However, the only symptoms that showed significant differences in strength centrality across samples were irritability and restlessness.

Conclusion

The current findings suggest that frustration, blurred vision and concentration difficulties may have an influential role in the experience and maintenance of post-concussion symptoms. The impact of these symptoms may remain stable over time. Targeting and prioritising the management of these symptoms may be beneficial for mTBI rehabilitation.

Sustained attention performance deficits in the three-choice serial reaction time task in male and female rats after experimental brain trauma

Impaired attention is central to the cognitive deficits associated with long-term sequelae for many traumatic brain injury (TBI) survivors. Assessing complex sustained attention post-TBI is clinically-relevant and may provide reliable avenues towards developing therapeutic and rehabilitation targets in both males and females. We hypothesized that rats subjected to a moderate TBI will exhibit attentional deficits seen as reduced accuracy and increased distractibility in an operant 3-choice serial reaction time task (3-CSRT), designed as an analogue of the clinical continuous performance test. Upon reaching baseline of 70% accuracy at the 300 ms cue, adult male and female Sprague-Dawley rats were subjected to a controlled cortical impact (2.8 mm deformation at 4 m/s) or sham injury over the right parietal cortex. After two weeks of recovery, they were retested on the 3-CSRT for ten days. Dependent measures include percent accuracy (overall and for each of the three cue ports), percent omissions, as well as latency to instrumental poke and retrieve reward. Results demonstrate that both males and females displayed reduced percent accuracy and increased omissions when re-tested post-TBI on 3-CSRT compared to Sham rats and to their own pre-insult baseline (p's < 0.05). Performance accuracy was impaired consistently throughout the ten days of post-surgery re-testing, suggesting pronounced and long-lasting dysfunction in sustained attention processes. Deficits were specifically more pronounced when the cue was pseudorandomly presented in the left-side cue port (p < 0.05), mirroring clinical hemispatial neglect. These data demonstrate significant and persistent complex attention impairments in both sexes after TBI, rendering identifying efficient therapies for cognitive recovery as pivotal.

Sensitivity and specificity of the INECO frontal screening (IFS) in the detection of patients with traumatic brain injury presenting executive deficits

Executive dysfunction (EF) is a common feature of adult traumatic brain injury (TBI), especially in moderate to severe cases. Assessing EF usually requires the administration of an extensive neuropsychological battery, which is time consuming and expensive. The INECO frontal screening (IFS) is a brief, easy-to-administer screening test which has previously shown to be useful in the detection of executive deficits in different psychiatric and neurological populations. The aim of the present study was to assess the usefulness of the IFS in the detection of executive dysfunction in TBI patients. Twenty-eight TBI patients and thirty-two healthy controls were assessed with a battery that included classical executive tests and the IFS. Our results indicated that with a cutoff score of 26.25 points, the IFS showed good sensitivity and specificity in the detection of executive impairments in TBI patients. It also showed good positive and negative predicted values. Our results suggest that the IFS can be considered a useful tool for identifying executive dysfunction in patients with TBI.

Inflammaging, cellular senescence, and cognitive aging after traumatic brain injury

Traumatic brain injury (TBI) is associated with mortality and morbidity worldwide. Accumulating pre-clinical and clinical data suggests TBI is the leading extrinsic cause of progressive neurodegeneration. Neurological deterioration after either a single moderate-severe TBI or repetitive mild TBI often resembles dementia in aged populations; however, no currently approved therapies adequately mitigate neurodegeneration. Inflammation correlates with neurodegenerative changes and cognitive dysfunction for years post-TBI, suggesting a potential association between immune activation and both age- and TBI-induced cognitive decline. Inflammaging, a chronic, low-grade sterile inflammation associated with natural aging, promotes cognitive decline. Cellular senescence and the subsequent development of a senescence associated secretory phenotype (SASP) promotes inflammaging and cognitive aging, although the functional association between senescent cells and neurodegeneration is poorly defined after TBI. In this mini-review, we provide an overview of the pre-clinical and clinical evidence linking cellular senescence with poor TBI outcomes. We also discuss the current knowledge and future potential for senotherapeutics, including senolytics and senomorphics, which kill and/or modulate senescent cells, as potential therapeutics after TBI.

Effects of intravascular photobiomodulation on cognitive impairment and crossed cerebellar diaschisis in patients with traumatic brain injury: a longitudinal study

The association between intravascular photobiomodulation (iPBM) and crossed cerebellar diaschisis (CCD) and cognitive dysfunction in patients with traumatic brain injury (TBI) remains unknown. We postulate that iPBM might enable greater neurologic improvements. The objective of this study was to evaluate the clinical impact of iPBM on the prognosis of patients with TBI. In this longitudinal study, patients who were diagnosed with TBI were recruited. CCD was identified from brain perfusion images when the uptake difference of both cerebella was > 20%. Thus, two groups were identified: CCD( +) and CCD( -). All patients received general traditional physical therapy and three courses of iPBM (helium-neon laser illuminator, 632.8 nm). Treatment assemblies were conducted on weekdays for 2 consecutive weeks as a solitary treatment course. Three courses of iPBM were performed over 2-3 months, with 1-3 weeks of rest between each course. The outcomes were measured using the Rancho Los Amigos Levels of Cognitive Functioning (LCF) tool. The chi-square test was used to compare categorical variables. Generalized estimating equations were used to verify the associations of various effects between the two groups. p < 0.05 indicated a statistically significant difference. Thirty patients were included and classified into the CCD( +) and CCD( -) groups (n = 15, each group). Statistics showed that before iPBM, CCD in the CCD( +) group was 2.74 (exp 1.0081) times higher than that of CCD( -) group (p = 0.1632). After iPBM, the CCD was 0.64 (exp-0.4436) times lower in the CCD( +) group than in the CCD( -) group (p < 0.0001). Cognitive assessment revealed that, before iPBM, the CCD( +) group had a non-significantly 0.1030 lower LCF score than that of CCD( -) group (p = 0.1632). Similarly, the CCD( +) group had a non-significantly 0.0013 higher score than that of CCD( -) after iPBM treatment (p = 0.7041), indicating no significant differences between the CCD( +) or CCD( -) following iPBM and general physical therapy. CCD was less likely to appear in iPBM-treated patients. Additionally, iPBM was not associated with LCF score. Administration of iPBM could be applied in TBI patients to reduce the occurrence of CCD. The study failed to show differences in cognitive function after iPBM, which still serves as an alternative non-pharmacological intervention.

The Labyrinthine Landscape of APP Processing: State of the Art and Possible Novel Soluble APP-Related Molecular Players in Traumatic Brain Injury and Neurodegeneration

Amyloid Precursor Protein (APP) and its cleavage processes have been widely investigated in the past, in particular in the context of Alzheimer’s Disease (AD). Evidence of an increased expression of APP and its amyloidogenic-related cleavage enzymes, β-secretase 1 (BACE1) and γ-secretase, at the hit axon terminals following Traumatic Brain Injury (TBI), firstly suggested a correlation between TBI and AD. Indeed, mild and severe TBI have been recognised as influential risk factors for different neurodegenerative diseases, including AD. In the present work, we describe the state of the art of APP proteolytic processing, underlining the different roles of its cleavage fragments in both physiological and pathological contexts. Considering the neuroprotective role of the soluble APP alpha (sAPPα) fragment, we hypothesised that sAPPα could modulate the expression of genes of interest for AD and TBI. Hence, we present preliminary experiments addressing sAPPα-mediated regulation of BACE1, Isthmin 2 (ISM2), Tetraspanin-3 (TSPAN3) and the Vascular Endothelial Growth Factor (VEGFA), each discussed from a biological and pharmacological point of view in AD and TBI. We finally propose a neuroprotective interaction network, in which the Receptor for Activated C Kinase 1 (RACK1) and the signalling cascade of PKCβII/nELAV/VEGF play hub roles, suggesting that vasculogenic-targeting therapies could be a feasible approach for vascular-related brain injuries typical of AD and TBI.

Temporal changes in the microglial proteome of male and female mice after a diffuse brain injury using label-free quantitative proteomics

Traumatic brain injury (TBI) triggers neuroinflammatory cascades mediated by microglia, which promotes tissue repair in the short-term. These cascades may exacerbate TBI-induced tissue damage and symptoms in the months to years post-injury. However, the progression of the microglial function across time post-injury and whether this differs between biological sexes is not well understood. In this study, we examined the microglial proteome at 3-, 7-, or 28-days after a midline fluid percussion injury (mFPI) in male and female mice using label-free quantitative proteomics. Data are available via ProteomeXchange with identifier PXD033628. We identified a reduction in microglial proteins involved with clearance of neuronal debris via phagocytosis at 3- and 7-days post-injury. At 28 days post-injury, pro-inflammatory proteins were decreased and anti-inflammatory proteins were increased in microglia. These results indicate a reduction in microglial clearance of neuronal debris in the days post-injury with a shift to anti-inflammatory function by 28 days following TBI. The changes in the microglial proteome that occurred across time post-injury did not differ between biological sexes. However, we did identify an increase in microglial proteins related to pro-inflammation and phagocytosis as well as insulin and estrogen signaling in males compared with female mice that occurred with or without a brain injury. Although the microglial response was similar between males and females up to 28 days following TBI, biological sex differences in the microglial proteome, regardless of TBI, has implications for the efficacy of treatment strategies targeting the microglial response post-injury.

The cognitive status of chronic subdural hematoma patients after treatment: an exploratory study

OBJECTIVE

Chronic subdural hematoma (CSDH) is a common neurological condition, often affecting the elderly. Cognitive impairment is frequently observed at presentation. However, the course and longer term aspects of the cognitive status of CSDH patients are unknown. In this study, we aim to explore the cognitive status of CSDH patients after treatment.

METHODS

An exploratory study in which CSDH patients were assessed 3 months after treatment and compared to healthy controls. A total of 56 CSDH patients (age 72.1 SD ± 10.8 years with 43 [77%] males) and 60 healthy controls were included (age 67.5 ± SD 4.8 with 34 [57%] males). Cognitive testing was performed using the Telephonic Interview of Cognitive Status-modified (TICS-m), a 12-item questionnaire in which a total of 50 points can be obtained on several cognitive domains.

RESULTS

Median time between treatment and cognitive testing was 93 days (range 76-139). TICS-m scores of CSDH patients were significantly lower than healthy controls, after adjusting for age and sex: mean score 34.6 (95% CI: 33.6-35.9) vs. 39.6 (95% CI: 38.5-40.7), p value < 0.001. More than half (54%) of CSDH patients have cognitive scores at follow-up that correspond with cognitive impairment.

CONCLUSION

A large number of CSDH patients show significantly worse cognitive status 3 months after treatment compared to healthy controls. This finding underlines the importance of increased awareness for impaired cognition after CSDH. Further research on this topic is warranted.

Nanoparticle-based drug delivery for the treatment of traumatic brain injury

INTRODUCTION

Traumatic brain injuries (TBIs) impact the breadth of society and remain without any approved pharmacological treatments. Despite successful Phase II clinical trials, the failure of many Phase III clinical trials may be explained by insufficient drug targeting and retention, preventing the proper attainment of an observable dosage threshold. To address this challenge, nanoparticles can be functionalized to protect pharmacological payloads, improve targeted drug delivery to sites of injury, and can be combined with supportive scaffolding to improve secondary outcomes.

AREAS COVERED

This review briefly covers the pathophysiology of TBIs and their subtypes, the current pre-clinical and clinical management strategies, explores the common models of focal, diffuse, and mixed traumatic brain injury employed in experimental animals, and surveys the existing literature on nanoparticles developed to treat TBIs.

EXPERT OPINION

Nanoparticles are well suited to improve secondary outcomes as their multifunctionality and customizability enhance their potential for efficient targeted delivery, payload protection, increased brain penetration, low off-target toxicity, and biocompatibility in both acute and chronic timescales.

Active immunotherapy against pathogenic Cis pT231-tau suppresses neurodegeneration in traumatic brain injury mouse models

Traumatic brain injury (TBI), characterized by acute neurological impairment, is associated with a higher incidence of neurodegenerative diseases, particularly chronic traumatic encephalopathy (CTE), Alzheimer's disease (AD), and Parkinson's disease (PD), whose hallmarks include hyperphosphorylated tau protein. Recently, phosphorylated tau at Thr231 has been shown to exist in two distinct cis and trans conformations. Moreover, targeted elimination of cis P-tau by passive immunotherapy with an appropriate mAb that efficiently suppresses tau-mediated neurodegeneration in severe TBI mouse models has proven to be a useful tool to characterize the neurotoxic role of cis P-tau as an early driver of the tauopathy process after TBI. Here, we investigated whether active immunotherapy can develop sufficient neutralizing antibodies to specifically target and eliminate cis P-tau in the brain of TBI mouse models. First, we explored the therapeutic efficacy of two different vaccines. C57BL/6 J mice were immunized with either cis or trans P-tau conformational peptides plus adjuvant. After rmTBI in mice, we found that cis peptide administration developed a specific Ab that precisely targeted and neutralized cis P-tau, inhibited the development of neuropathology and brain dysfunction, and restored various structural and functional sequelae associated with TBI in chronic phases. In contrast, trans P-tau peptide application not only lacked neuroprotective properties, but also contributed to a number of neuropathological features, including progressive TBI-induced neuroinflammation, widespread tau-mediated neurodegeneration, worsening functional deficits, and brain atrophy. Taken together, our results suggest that active immunotherapy strategies against pathogenic cis P-tau can halt the process of tauopathy and would have profound clinical implications.

Olfactory training - Thirteen years of research reviewed

The sense of smell is interrelated with psychosocial functioning. Olfactory disorders often decrease quality of life but treatment options for people with olfactory loss are limited. Additionally, olfactory loss accompanies and precedes psychiatric and neurodegenerative diseases. Regular, systematic exposure to a set of odors, i.e., olfactory training (OT) has been offered for rehabilitation of the sense of smell in clinical practice. As signals from the olfactory bulb are directly projected to the limbic system it has been also debated whether OT might benefit psychological functioning, i.e., mitigate cognitive deterioration or improve emotional processing. In this review we synthesize key findings on OT utility in the clinical practice and highlight the molecular, cellular, and neuroanatomical changes accompanying olfactory recovery in people with smell loss as well as in experimental animal models. We discuss how OT and its modifications have been used in interventions aiming to support cognitive functions and improve well-being. We delineate main methodological challenges in research on OT and suggest areas requiring further scientific attention.

Brain age estimation reveals older adults' accelerated senescence after traumatic brain injury

Adults aged 60 and over are most vulnerable to mild traumatic brain injury (mTBI). Nevertheless, the extent to which chronological age (CA) at injury affects TBI-related brain aging is unknown. This study applies Gaussian process regression to T1-weighted magnetic resonance images (MRIs) acquired within [Formula: see text]7 days and again [Formula: see text]6 months after a single mTBI sustained by 133 participants aged 20-83 (CA [Formula: see text] = 42.6 ± 17 years; 51 females). Brain BAs are estimated, modeled, and compared as a function of sex and CA at injury using a statistical model selection procedure. On average, the brains of older adults age by 15.3 ± 6.9 years after mTBI, whereas those of younger adults age only by 1.8 ± 5.6 years, a significant difference (Welch's t32 =  - 9.17, p ≃ 9.47 × 10-11). For an adult aged [Formula: see text]30 to [Formula: see text]60, the expected amount of TBI-related brain aging is [Formula: see text]3 years greater than in an individual younger by a decade. For an individual over [Formula: see text]60, the respective amount is [Formula: see text]7 years. Despite no significant sex differences in brain aging (Welch's t108 = 0.78, p > 0.78), the statistical test is underpowered. BAs estimated at acute baseline versus chronic follow-up do not differ significantly (t264 = 0.41, p > 0.66, power = 80%), suggesting negligible TBI-related brain aging during the chronic stage of TBI despite accelerated aging during the acute stage. Our results indicate that a single mTBI sustained after age [Formula: see text]60 involves approximately [Formula: see text]10 years of premature and lasting brain aging, which is MRI detectable as early as [Formula: see text]7 days post-injury.

Domain-Specific Cognitive Prosthesis for Face Memory and Recognition

The present study proposes a cognitive prosthesis device for face memory impairment as a proof-of-concept for the domain-specific cognitive prosthesis. Healthy subjects (n = 6) and a patient with poor face memory were enrolled. An acquaintance face recognition test with and without the use of cognitive prosthesis for face memory impairment, face recognition tests, quality of life, neuropsychological assessments, and machine learning performance of the cognitive prosthesis were followed-up throughout four weeks of real-world device use by the patient. The healthy subjects had an accuracy of 92.38 ± 4.41% and reaction time of 1.27 ± 0.12 s in the initial attempt of the acquaintance face recognition test, which changed to 80.48 ± 6.23% (p = 0.06) and 2.11 ± 0.20 s (p < 0.01) with prosthesis use. The patient had an accuracy of 74.29% and a reaction time of 6.65 s, which improved to 94.29% and 3.28 s with prosthesis use. After four weeks, the patient’s unassisted accuracy and reaction time improved to 100% and 1.23 s. Functional MRI study revealed activation of the left superior temporal lobe during face recognition task without prosthesis use and activation of the right precentral motor area with prosthesis use. The prosthesis could improve the patient’s performance by bypassing the brain area inefficient for facial recognition and employing the area more efficiently for the cognitive task.

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.

Interleukin-10 deficiency aggravates traumatic brain injury in male but not female mice

The goal of this study was to determine whether deficiency of anti-inflammatory cytokine interleukin-10 (IL-10) affects traumatic brain injury (TBI) outcomes in a sex-dependent manner. Moderate TBI was induced by controlled cortical impact in 8-10 week-old wild-type and IL-10-deficient mice. In wild-type mice, serum IL-10 was significantly increased after TBI in males but not in females. At 4-5 weeks after TBI, sensorimotor function, cognitive function (Y-maze and novel object recognition tests), anxiety-related behavior (light-dark box and open field test), and depression-like behavior (forced swim test) were assessed. IL-10-deficient male mice had larger lesion volumes than did wild-type mice in the early recovery phase and worse performance on sensorimotor tasks, cognitive tests, and anxiety- and depression-related tests in the late recovery phase, whereas female IL-10-deficient mice had lesion volume equivalent to that of wild-type females and worse performance only on sensorimotor tasks. At 3 days after TBI, the number of GFAP- and Iba1-positive cells were augmented in areas in proximity to the injury (cerebral cortex and hippocampus) and in remote functional regions (striatum and amygdala) of IL-10-deficient male, but not female, mice. Moreover, on day 35, significantly fewer NeuN-positive cells were present in cortex, striatum, and amygdala of IL-10-deficient male mice than in wild-type males. This difference was not evident in females. We conclude that IL-10 deficiency aggravates cognitive and emotional recovery from TBI in association with enhanced gliosis and neuronal loss selectively in males, suggesting that recruitment of this cytokine limits damage in a sex-dependent manner.

Traumatic brain injury in Brazil: an epidemiological study and systematic review of the literature

BACKGROUND

Traumatic brain injury (TBI) is a serious public health problem worldwide. Although TBI is common in developing countries, there are few epidemiological studies.

OBJECTIVE

To investigate the sociodemographic and clinical features of patients with TBI at the Hospital João XXIII, a public reference center for trauma in Belo Horizonte, Brazil, and to systematically review the available literature on TBI in Brazil.

METHODS

Clinical and sociodemographic data were collected from electronic medical records for the entire month of July 2016. The literature on epidemiology of TBI in Brazil was systematically reviewed using MeSH/DeCS descriptors in the PubMed and Lilacs databases.

RESULTS

Most patients admitted with TBI were male and under 60 years of age. Mild TBI was the most prevalent form and the most common cause of TBI was falls. A Glasgow Coma Scale score below 12, neuroimaging changes on computer tomography, and presence of any medical conditions were significantly associated with longer hospital stay. Brazilian studies showed that TBI affected mainly men and young adults. In addition, mild TBI was the most common TBI severity reported and the most common causes were motor vehicle accidents and falls.

CONCLUSIONS

Overall, the profile of TBI in this center reflects the data from other Brazilian studies.

Hypertension and advanced age increase the risk of cognitive impairment after mild traumatic brain injury: A registry-based study

OBJECTIVE

As the global population ages, the incidence of traumatic brain injury (TBI) increases. While mild TBI can impair the cognitive function of older adults, the cause and background of mild TBI-induced cognitive impairment remains unclear, and the evaluation of risk factors for cognitive impairment after mild TBI remain open for consideration especially in the current aging society. This study aimed to evaluate the risks associated with cognitive impairment following mild TBI.

METHODS

Between January 2006 and December 2018, 2,209 patients with TBI required hospitalization in Shimane Prefectural Central Hospital. Mild TBI was defined as a Japan coma scale ≤ 10 at admission. The cognitive function of the patients was measured with the Hasegawa Dementia Rating Scale-revised or Mini-mental state examination at least twice during the patients' hospital stays. The odds ratio (OR) and 95% confidence interval (CI) of each considered risk factor was calculated with multivariable logistic regression analysis after univariate analysis.

RESULTS

Among 1,674 patients with mild TBI, 172 patients underwent cognitive function examinations, and 145 patients (84.3%) were found to have cognitive impairment at discharge. Significant risk factors for cognitive impairment included age (P = 0.008) and hypertension (P = 0.013) in univariate analysis; and age (OR 1.04: 95% CI 1.01-1.07) and hypertension (OR 5.81: 95% CI 1.22-27.68) by multivariable analysis.

CONCLUSIONS

Older patients with hypertension displayed significantly higher cognitive impairment risk after even mild TBI. For these patients, we should take carefully management even after mild TBI.

Cognitive profile of mild traumatic brain injury patients requiring acute hospitalization - A UC davis cognitive screener (UCD-Cog) study

OBJECTIVE

Identification of patients with mTBI at risk for developing persistent-post concussive syndromes should begin during the ED/inpatient evaluation due to frequent lack of post-discharge follow-up. The best method for evaluating cognitive deficits in these acute settings and how to utilize this information to optimize follow-up care is a matter of ongoing research. In this descriptive study, we present the cognitive profile of 214 hospitalized patients with mTBI using a novel cognitive and behavioral screener, the UCD-Cog.

METHOD

A retrospective review of patients with mTBI requiring hospitalization who were enrolled in the UC Davis TBI Registry over the course of 1 year.

RESULTS

Reasoning, executive function, and delayed recall were the most frequently impaired cognitive domains. GCS 13-14 was associated with higher numbers of impaired cognitive domains and frequencies of impairments in domains traditionally associated with post-concussive symptoms. Patients with abnormal UCD-Cog results, regardless of GCS, were recommended higher levels of post-discharge care and supervision.

CONCLUSION

Inpatient cognitive profiles using the UCD-Cog were consistent with evaluations during the subacute/chronic phase of mTBI and supports the clinical utility of acute cognitive screeners for mTBI management. Future studies will determine how the acute cognitive assessments correlate with long-term mTBI outcomes.

Real-Time Noninvasive Bioluminescence, Ultrasound and Photoacoustic Imaging in NFκB-RE-Luc Transgenic Mice Reveal Glia Maturation Factor-Mediated Immediate and Sustained Spatio-Temporal Activation of NFκB Signaling Post-Traumatic Brain Injury in a Gender-Specific Manner

Neurotrauma especially traumatic brain injury (TBI) is the leading cause of death and disability worldwide. To improve upon the early diagnosis and develop precision-targeted therapies for TBI, it is critical to understand the underlying molecular mechanisms and signaling pathways. The transcription factor, nuclear factor kappa B (NFκB), which is ubiquitously expressed, plays a crucial role in the normal cell survival, proliferation, differentiation, function, as well as in disease states like neuroinflammation and neurodegeneration. Here, we hypothesized that real-time noninvasive bioluminescence molecular imaging allows rapid and precise monitoring of TBI-induced immediate and rapid spatio-temporal activation of NFκB signaling pathway in response to Glia maturation factor (GMF) upregulation which in turn leads to neuroinflammation and neurodegeneration post-TBI. To test and validate our hypothesis and to gain novel mechanistic insights, we subjected NFκB-RE-Luc transgenic male and female mice to TBI and performed real-time noninvasive bioluminescence imaging (BLI) as well as photoacoustic and ultrasound imaging (PAI). Our BLI data revealed that TBI leads to an immediate and sustained activation of NFκB signaling. Further, our BLI data suggest that especially in male NFκB-RE-Luc transgenic mice subjected to TBI, in addition to brain, there is widespread activation of NFκB signaling in multiple organs. However, in the case of the female NFκB-RE-Luc transgenic mice, TBI induces a very specific and localized activation of NFκB signaling in the brain. Further, our microRNA data suggest that TBI induces significant upregulation of mir-9-5p, mir-21a-5p, mir-34a-5p, mir-16-3p, as well as mir-155-5p within 24 h and these microRNAs can be successfully used as TBI-specific biomarkers. To the best of our knowledge, this is one of the first and unique study of its kind to report immediate and sustained activation of NFκB signaling post-TBI in a gender-specific manner by utilizing real-time non-invasive BLI and PAI in NFκB-RE-Luc transgenic mice. Our study will prove immensely beneficial to gain novel mechanistic insights underlying TBI, unravel novel therapeutic targets, as well as enable us to monitor in real-time the response to innovative TBI-specific precision-targeted gene and stem cell-based precision medicine.

Improving Outcomes for Work-Related Concussions: A Mental Health Screening and Brief Therapy Model

OBJECTIVE

This study assessed the efficacy of a neurocognitive screening evaluation and brief therapy model to improve RTW outcomes for workers who experienced mild head injuries.

METHODS

Patients referred were evaluated using a neurocognitive and psychological screening battery. Work-focused cognitive behavioral therapy was provided when appropriate, addressing the role of negative emotional adjustment and functional sleep disturbance in prolonging recovery.

RESULTS

Average time to RTW was 7 weeks post-evaluation, despite workers being off an average of 10 months between injury and referral dates. Overall, 99% were released to full-duty work without restrictions or accommodations.

CONCLUSIONS

This study demonstrates the favorable outcomes achieved via a structured, clinically driven program for workers who experience head-involved injuries, validating previous research on the importance of recognizing the role of psychological factors in prolonging concussion recovery.

Hevin-calcyon interaction promotes synaptic reorganization after brain injury

Hevin, also known as SPARC-like protein 1 (SPARCL1 or SC1), is a synaptogenic protein secreted by astrocytes and modulates the formation of glutamatergic synapses in the developing brain by interacting with synaptic adhesion proteins, such as neurexin and neuroligin. Here, we identified the neuron-specific vesicular protein calcyon as a novel interaction partner of hevin and demonstrated that this interaction played a pivotal role in synaptic reorganization after an injury in the mature brain. Astrocytic hevin was upregulated post-injury in a photothrombotic stroke model. Hevin was fragmented by MMP3 induced during the acute stage of brain injury, and this process was associated with severe gliosis. At the late stage, the functional hevin level was restored as MMP3 expression decreased. The C-terminus of hevin interacted with the N-terminus of calcyon. By using RNAi and binding competitor peptides in an ischemic brain injury model, we showed that this interaction was crucial in synaptic and functional recoveries in the sensory-motor cortex, based on histological and electrophysiological analyses. Regulated expression of hevin and calcyon and interaction between them were confirmed in a mouse model of traumatic brain injury and patients with chronic traumatic encephalopathy. Our study provides direct evidence for the causal relationship between the hevin-calcyon interaction and synaptic reorganization after brain injury. This neuron-glia interaction can be exploited to modulate synaptic reorganization under various neurological conditions.

Possible Predictive Factor of Acute Respiratory Distress Syndrome Development After Mild Traumatic Brain Injury: A Single Rural Trauma Center Preliminary Study

Introduction Acute respiratory distress syndrome (ARDS) after mild traumatic brain injury (TBI) can be associated with significant morbidity and mortality. This study aimed to evaluate the potential predictive factors of ARDS development following mild TBI in trauma patients. Methods A retrospective chart review was done for adult trauma patients with mild TBI (GCS 13-15) requiring admission at our center from 2012 to 2020. Linear regression analysis and chi-square test were utilized to identify independent predictors of the association with ARDS in adults with mild TBI.  Results A total of 784 mild TBI patients were admitted during the time of interest; 34 patients developed ARDS during their index hospitalization. Patients who had ARDS were more likely to have acute kidney injury (AKI; p < 0.0001), sepsis (p < 0.01), rib fractures (p < 0.05), use of anticoagulants (p < 0.001), deep vein thrombosis (p < 0.001), transfusion during the first 4four hours upon admission (p = 0.01), intravenous fluid (IVF) resuscitation during the first four hours (p <0.05), the first eight hours (p = 0.01), the first 12 hours (p = 0.03), and intubation upon the admission (p < 0.0001). ARDS associated with mild TBI demonstrated a statistically significant increase in mortality during the index hospitalization (p < 0.0001). Conclusion ARDS after mild TBI can be associated with significant morbidity and mortality. Key risk factors identified include AKI, sepsis, anticoagulant use, deep vein thrombosis (DVT), transfusion in the first four hours, IVF resuscitation in the first four, eight, and 12 hours, and intubation upon admission.

Effect of repetitive transcranial magnetic stimulation on depression and cognition in individuals with traumatic brain injury: a systematic review and meta-analysis

Repetitive transcranial magnetic stimulation (rTMS) is an FDA-approved therapy in major depressive disorder. However, its treatment efficacy on depression after traumatic brain injury (TBI) remains inconclusive. We conducted a meta-analysis to assess the effectiveness of executing rTMS over dorsolateral prefrontal cortex (DLPFC) on depression, cognitive impairment and post-concussion syndrome in individuals with traumatic brain injury. This study contained seven randomized controlled trials that published before April 5, 2020 in PubMed, Embase, Scopus, Cochrane, and Web of Science databases. The rTMS had significant anti-depressant effect (SMD = 1.03, p = 0.02), but the effects dissipated at 1-month follow-up (SMD = 0.39, p = 0.62). In the subgroup analysis, only applying rTMS to left DLPFC area of post-TBI patients showed significant anti-depressant effect (SMD = 0.98, p = 0.04). Moreover, current data observed that rTMS on post-TBI patients possessed substantial improvement in visuospatial memory (SMD = 0.39, p < 0.0001), but wasn't in processing speed (SMD = - 0.18, p = 0.32) and selective attention (SMD = 0.21, p = 0.31). In addition, the effect of rTMS is not superior to sham on postconcussion syndrome. In conclusion, the short-term antidepressant effect of left DLPFC rTMS in patients with TBI was significant. However, the effectiveness of rTMS on cognition and postconcussion syndrome in patients with post-TBI depression was limited.

Intervention Effect of Non-Invasive Brain Stimulation on Cognitive Functions among People with Traumatic Brain Injury: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aggregated and examined the treatment effect of non-invasive brain stimulation (NIBS) (transcranial direct current stimulation and transcranial magnetic stimulation) on cognitive functions in people with traumatic brain injury (TBI). A systematic search was conducted using databases (PubMed, Web of Science, Scopus, PsycINFO, EMBASE) for studies with keywords related to non-randomized and randomized control trials of NIBS among people with TBI. Nine out of 1790 NIBS studies with 197 TBI participants (103 active vs. 94 sham) that met the inclusion and exclusion criteria of the present study were finally selected for meta-analysis using Comprehensive Meta-Analysis software (version 3). Results showed that the overall effect of NIBS on cognition in people with TBI was moderately significant (g = 0.304, 95% CI = 0.055 to 0.553) with very low heterogeneity across studies (I² = 0.000, Tau = 0.000). Specifically, significant and marginally significant moderate effect sizes were found for cognitive sub-domains including attention, memory, and executive function. The present findings suggest that NIBS is moderately effective in improving cognitive functions among people with TBI. In particular, NIBS may be used as an alternative and/or an adjunct treatment to the traditional approach in rehabilitating cognitive functions in people with TBI.

Acute cognitive impairment after traumatic brain injury predicts the occurrence of brain atrophy patterns similar to those observed in Alzheimer's disease

Traumatic brain injuries (TBIs) are often followed by persistent structural brain alterations and by cognitive sequalae, including memory deficits, reduced neural processing speed, impaired social function, and decision-making difficulties. Although mild TBI (mTBI) is a risk factor for Alzheimer's disease (AD), the extent to which these conditions share patterns of macroscale neurodegeneration has not been quantified. Comparing such patterns can not only reveal how the neurodegenerative trajectories of TBI and AD are similar, but may also identify brain atrophy features which can be leveraged to prognosticate AD risk after TBI. The primary aim of this study is to systematically map how TBI affects white matter (WM) and gray matter (GM) properties in AD-analogous patterns. Our findings identify substantial similarities in the regional macroscale neurodegeneration patterns associated with mTBI and AD. In cerebral GM, such similarities are most extensive in brain areas involved in memory and executive function, such as the temporal poles and orbitofrontal cortices, respectively. Our results indicate that the spatial pattern of cerebral WM degradation observed in AD is broadly similar to the pattern of diffuse axonal injury observed in TBI, which frequently affects WM structures like the fornix, corpus callosum, and corona radiata. Using machine learning, we find that the severity of AD-like brain changes observed during the chronic stage of mTBI can be accurately prognosticated based on acute assessments of post-traumatic mild cognitive impairment. These findings suggest that acute post-traumatic cognitive impairment predicts the magnitude of AD-like brain atrophy, which is itself associated with AD risk.

The Figure Memory Test: diagnosis of memory impairment in populations with heterogeneous educational background

Diagnosis of cognitive impairment is usually difficult in low-educated individuals. The Brief Cognitive Screening Battery (BCSB) was designed as a screening tool for the evaluation of cognitive impairment in low-educated individuals, but it may also be used for evaluating individuals with high educational level.

OBJECTIVES

To perform a narrative review analyzing the origin of the BCSB, to report all studies that have used the Figure Memory Test (FMT) of the BCSB, and to demonstrate that it is a useful battery for regions where populations have heterogeneous educational background.

METHODS

We performed a search in PubMed, SciELO, and LILACS using the terms "Brief Cognitive Screening Battery" and "Brief Cognitive Battery".

RESULTS

We obtained 49 papers from PubMed, 32 from SciELO, and 28 from LILACS. After the exclusion of duplicate papers, 54 publications were obtained; five more studies were included from previous knowledge of the authors. Twenty-four papers were related to the impact of education on performance, diagnostic accuracy, cutoff scores and normative studies. The delayed recall of the FMT showed the best accuracy for the diagnosis of dementia with a cutoff score of ≤5 in different education levels. In 35 papers, the FMT of the BCSB was used in clinical studies with different settings, from outpatient memory clinics to epidemiological studies and evaluation of Amazon river basin dwelling individuals, and it was always considered to be easy to apply.

CONCLUSIONS

The FMT of the BCSB is an easy and short tool for the diagnosis of dementia in populations with heterogeneous educational background.