Fatigue before and after mild traumatic brain injury: Pre–post-injury comparisons in relation toApolipoproteinE

Association of Alzheimer's disease polygenic risk score with concussion severity and recovery metrics

Identification of genetic alleles associated with both Alzheimer's disease (AD) and concussion severity/recovery could help explain the association between concussion and elevated dementia risk. However, there has been little investigation into whether AD risk genes associate with concussion severity/recovery, and the limited findings are mixed. We used AD polygenic risk scores (PRS) and APOE genotypes to investigate any such associations in the NCAA-DoD Grand Alliance CARE Consortium (CARE) dataset. We assessed six outcomes in 931 total participants. The outcomes were two concussion recovery measures (number of days to asymptomatic status, number of days to return to play (RTP)) and four concussion severity measures (scores on SAC and BESS, SCAT symptom severity, and total number of symptoms). We calculated PRS using a published score [1] and performed multiple linear regression (MLR) to assess the relationship of PRS with the outcomes. We also used t-tests and chi-square tests to examine outcomes by APOE genotype, and MLR to analyze outcomes in European and African genetic ancestry subgroups. Higher PRS was associated with longer injury to RTP in the normal RTP (<24 days) subgroup ( p = 0.024), and one standard deviation increase in PRS resulted in a 9.89 hour increase to the RTP interval. There were no other consistently significant effects, suggesting that high AD genetic risk is not strongly associated with more severe concussions or poor recovery in young adults. Future studies should attempt to replicate these findings in larger samples with longer follow-up using PRS calculated from diverse populations.

Genetic Variants and Persistent Impairment Following Mild Traumatic Brain Injury: A Systematic Review

OBJECTIVE

The purpose of this review is to systematically assess primary research publications on known genetic variants, which modify the risk for symptoms or dysfunction persisting 30 days or more following mild traumatic brain injury (mTBI).

SUMMARY OF REVIEW

A search of PubMed and Embase from inception through June 2022 identified 42 studies that associated genetic variants with the presence of symptoms or cognitive dysfunction 30 days or more following mTBI. Risk of bias was assessed for each publication using the Newcastle Ottawa Scale (NOS). Fifteen of the 22 studies evaluating apolipoprotein E ( APOE ) ɛ4 concluded that it was associated with worse outcomes and 4 of the 8 studies investigating the brain-derived neurotrophic factor ( BDNF ) reported the Val66Met allele was associated with poorer outcomes. The review also identified 12 studies associating 28 additional variants with mTBI outcomes. Of these, 8 references associated specific variants with poorer outcomes. Aside from analyses comparing carriers and noncarriers of APOE ɛ4 and BDNF Val66Met, most of the reviewed studies were too dissimilar, particularly in terms of specific outcome measures but also in genes examined, to allow for direct comparisons of their findings. Moreover, these investigations were observational and subject to varying degrees of bias.

CONCLUSIONS

The most consistent finding across articles was that APOE ɛ4 is associated with persistent post-mTBI impairment (symptoms or cognitive dysfunction) more than 30 days after mTBI. The sparsity of other well-established and consistent findings in the mTBI literature should motivate larger, prospective studies, which characterize the risk for persistent impairment with standardized outcomes in mTBI posed by other genetic variants influencing mTBI recovery.

APOE-ε4 Is Associated With Reduced Verbal Memory Performance and Higher Emotional, Cognitive, and Everyday Executive Function Symptoms Two Months After Mild Traumatic Brain Injury

Background

Substantial variance exists in outcomes after mild traumatic brain injury (MTBI), and these differences are not fully explained by injury characteristics or severity. Genetic factors are likely to play a role in this variance.

Objectives

The aim of this study was to examine associations between the apolipoprotein (APOE)-ε4 allele and memory measures at two months post-MTBI and to evaluate whether subjective cognitive and affective symptoms were associated with APOE-ε4 status. Based on previous research, it was hypothesized that APOE-ε4 carriers would show poorer verbal memory performance compared to APOE-ε4 non-carriers.

Methods

Neuropsychological data at two months post-injury and blood samples that could be used to assess APOE genotype were available for 134 patients with MTBI (mean age 39.2 years, 62% males, 37% APOE-ε4 carriers). All patients underwent computed tomography at hospital admission and magnetic resonance imaging four weeks post-injury.

Results

The APOE-ε4 + status was associated with decreased immediate memory recall (p = 0.036; β = −0.10, 95% CI [−0.19, −0.01]). Emotional, cognitive, and everyday executive function symptoms at two months post-injury were significantly higher in APOE-ε4 carriers compared to non-carriers.

Conclusion

The APOE-ε4+ allele has a negative effect on verbal memory and symptom burden two months after MTBI.

Apolipoprotein E e4 is associated with worse self-reported neurobehavioral symptoms following uncomplicated mild traumatic brain injury in U.S. military service members

Past research has found a relationship between the apolipoprotein E (APOE) e4 allele and worse neurobehavioral functioning following mild traumatic brain injury (MTBI) in civilian populations. The purpose of this study was to examine this relationship in service members and veterans (SMVs) following MTBI. Participants were 151 SMVs (103 uncomplicated MTBI; 48 Injured Controls [IC]) prospectively enrolled in the DVBIC-TBICoE 15-Year Longitudinal TBI Study. Participants completed a battery of self-reported neurobehavioral symptom measures on average 76.2 months post-injury (SD = 31.8). APOE genotyping was undertaken using non-fasting blood samples. Participants were classified into four subgroups based on injury (MTBI vs. IC) and APOE e4 allele status (e4 present/absent). In the IC group, there were no significant differences across APOE e4 status subgroups for all measures. In the MTBI group, participants with the APOE e4 allele had significantly worse scores on measures of depression, pain, anxiety, grief, positive well-being, social participation, and resilience compared to those without the e4 allele (d = .44 to d = .69). When comparing the number of 'clinically elevated' neurobehavioral measures simultaneously, the MTBI/e4 present subgroup consistently had a higher number of elevated measures compared to the MTBI/e4 absent, IC/e4 present, and IC/e4 absent subgroups. The APOE e4 allele was associated with poorer neurobehavioral outcome in SMVs in the chronic phase of recovery following MTBI. APOE e4 could be incorporated into screening tools to predict SMVs at risk for poor long-term neurobehavioral outcome in an effort to provide early intervention to improve long-term clinical outcome.

Mental Fatigue after Mild Traumatic Brain Injury in Relation to Cognitive Tests and Brain Imaging Methods

Most people recover within months after a mild traumatic brain injury (TBI) or concussion, but some will suffer from long-term fatigue with a reduced quality of life and the inability to maintain their employment status or education. For many people, mental fatigue is one of the most distressing and long-lasting symptoms following an mTBI. No efficient treatment options can be offered. The best method for measuring fatigue today is with fatigue self-assessment scales, there being no objective clinical tests available for mental fatigue. The aim here is to provide a narrative review and identify fatigue in relation to cognitive tests and brain imaging methods. Suggestions for future research are presented.

Apolipoprotein E4 Polymorphism and Outcomes from Traumatic Brain Injury: A Living Systematic Review and Meta-Analysis

The mortality of traumatic brain injury (TBI) has been largely static despite advances in monitoring and imaging techniques. Substantial variance exists in outcome, not fully accounted for by baseline characteristics or injury severity, and genetic factors likely play a role in this variance. The aims of this systematic review were to examine the evidence for a link between the apolipoprotein E4 (APOE4) polymorphism and TBI outcomes and where possible, to quantify the effect size via meta-analysis. We searched EMBASE, MEDLINE, CINAHL, and gray literature in December 2017. We included studies of APOE genotype in relation to functional adult TBI outcomes. Methodological quality was assessed using the Quality in Prognostic Studies Risk of Bias Assessment Instrument and the prognostic studies adaptation of the Grading of Recommendations Assessment, Development and Evaluation tool. In addition, we contacted investigators and included an additional 160 patients whose data had not been made available for previous analyses, giving a total sample size of 2593 patients. Meta-analysis demonstrated higher odds of a favorable outcome following TBI in those not possessing an ApoE ɛ4 allele compared with ɛ4 carriers and homozygotes (odds ratio 1.39, 95% confidence interval 1.05 to 1.84; p = 0.02). The influence of APOE4 on neuropsychological functioning following TBI remained uncertain, with multiple conflicting studies. We conclude that the ApoE ɛ4 allele confers a small risk of poor outcome following TBI, with analysis by TBI severity not possible based on the currently available published data. Further research into the long-term neuropsychological impact and risk of dementia is warranted.

Molecular and Diffusion Tensor Imaging Biomarkers of Traumatic Brain Injury: Principles for Investigation and Integration

The last 20 years have seen the advent of new technologies that enhance the diagnosis and prognosis of traumatic brain injury (TBI). There is recognition that TBI affects the brain beyond initial injury, in some cases inciting a progressive neuropathology that leads to chronic impairments. Medical researchers are now searching for biomarkers to detect and monitor this condition. Perhaps the most promising developments are in the biomolecular and neuroimaging domains. Molecular assays can identify proteins indicative of neuronal injury and/or degeneration. Diffusion imaging now allows sensitive evaluations of the brain's cellular microstructure. As the pace of discovery accelerates, it is important to survey the research landscape and identify promising avenues of investigation. In this review, we discuss the potential of molecular and diffusion tensor imaging (DTI) biomarkers in TBI research. Integration of these technologies could advance models of disease prognosis, ultimately improving care. To date, however, few studies have explored relationships between molecular and DTI variables in patients with TBI. Here, we provide a short primer on each technology, review the latest research, and discuss how these biomarkers may be incorporated in future studies.

Apolipoprotein E Polymorphism and Frailty: Apolipoprotein ε4 Allele Is Associated with Fatigue but Not Frailty Syndrome in a Community-Dwelling Older Population Cohort

OBJECTIVE

Frailty is known to be influenced by genetics, however, little evidence on the association of Apolipoprotein E (ApoE) genotype and frailty exists which we aim to investigate.

DESIGN

This study is a cross-sectional analysis from a prospective longitudinal study cohort.

SETTING AND PARTICIPANTS

Community-dwelling individuals aged 55 years and older from Beijing region in China.

MEASUREMENTS

A total of 3,569 older adults with a mean age of 75.06(±6.79) years were included. We investigated the association between ApoE polymorphism and frailty syndrome using the frailty index (FI) and frailty phenotype (including association with individual components of the frailty phenotype). Logistic regressions were performed to investigate the relation between ApoE variants and frailty.

RESULTS

There was no significant association between ApoE variants and frailty as assessed by the FI. In the age and sex-adjusted model, compared to the ApoE e3/e3 carriers ApoE e4 carriers had almost 1.5 times higher odds of being frail as assessed by the frailty phenotype. However, the significance was lost on the model with adjustment for cognitive impairment. Compared to the ApoE e3/e3 carriers ApoE e4 carriers had almost two times higher odds of fatigue. ApoE e4 heterozygotes had higher odds of fatigue compared to ApoE e4 non-carriers. No significant association was found between ApoE variants and other components of frailty phenotype.

CONCLUSIONS

Our findings do not support an association between ApoE genotype and frailty irrespective of the frailty assessment tools. Fatigue in older adults is the only component of frailty phenotype influenced by ApoE genotype.

Biological and environmental predictors of heterogeneity in neurocognitive ageing: Evidence from Betula and other longitudinal studies

Individual differences in cognitive performance increase with advancing age, reflecting marked cognitive changes in some individuals along with little or no change in others. Genetic and lifestyle factors are assumed to influence cognitive performance in ageing by affecting the magnitude and extent of age-related brain changes (i.e., brain maintenance or atrophy), as well as the ability to recruit compensatory processes. The purpose of this review is to present findings from the Betula study and other longitudinal studies, with a focus on clarifying the role of key biological and environmental factors assumed to underlie individual differences in brain and cognitive ageing. We discuss the vital importance of sampling, analytic methods, consideration of non-ignorable dropout, and related issues for valid conclusions on factors that influence healthy neurocognitive ageing.

Factors influencing recovery from mild traumatic brain injury

PRIMARY OBJECTIVE

This study determined whether initial GCS score, head CT results, cognitive performance on IMPACT testing, or APOE genotype most effectively predicted 1-month functional outcome after mild traumatic brain injury (mTBI). This study tested the hypotheses that participants with poor performance on initial cognitive testing and those with an APOEe4 genotype would exhibit a poorer 1-month recovery after mTBI.

RESEARCH DESIGN

Regression analysis determined which independent variables were most effective in predicting 1-month GOS-E or DRS score. Independent t-test procedures determined whether cognitive recovery varied across APOEe4 carriers.

METHODS AND PROCEDURES

49 participants admitted to the hospital with mTBI received cognitive evaluation within 48 hours after injury and again one month later. DNA analysis provided participant APOE genotype.

MAIN OUTCOMES AND RESULTS

Results showed that no study variables significantly predicted GOS-E or DRS scores, however, differences were identified when APOE groups were compared. Participants who were noncarriers of APOEe4 had significantly slower reaction times compared to APOEe4 carriers. Participants who were homozygous APOEe4 carriers had significantly lower instances of impulsivity than noncarriers.

CONCLUSIONS

Further research is needed to understand how APOE allele status and performance on initial cognitive testing may influence short-term recovery after mTBI.

Sleep and fatigue after TBI

BACKGROUND

Whilst post traumatic brain injury fatigue (PTBIF) and sleep disturbance are common sequelae following brain injury, underlying mechanisms, and the potential for targeted interventions remain unclear.

OBJECTIVE

To present a review of recent studies exploring the epidemiology of PTBIF and sleep disturbance, the relationship and neuropsychological correlates of these issues, potential approaches to intervention, and implications for neurorehabilitation.

METHODS

A review of relevant literature was undertaken, with a focus on PTBIF relating to sleep disturbance, the neuropsychological correlates of these issues and implications for neurorehabilitation. This paper does not set out to provide a systematic review.

RESULTS

Multidimensional approaches to assessment and treatment of sleep disturbance and PTBIF are required.

CONCLUSIONS

There is a need for more robust findings in determining the complex nature of relationships between PTBIF, sleep disturbance, and correlates. Longitudinal prospective data is required to increase our understanding of the nature and course of PTBIF and sleep disturbance post TBI. Large scale clinical trials are required in evaluating the potential benefits of interventions.

Apolipoprotein E Epsilon 4 Genotype, Mild Traumatic Brain Injury, and the Development of Chronic Traumatic Encephalopathy

The annual incidence of mild traumatic brain injury (MTBI) is 3.8 million in the USA with 10⁻15% experiencing persistent morbidity beyond one year. Chronic traumatic encephalopathy (CTE), a neurodegenerative disease characterized by accumulation of hyperphosphorylated tau, can occur with repetitive MTBI. Risk factors for CTE are challenging to identify because injury mechanisms of MTBI are heterogeneous, clinical manifestations and management vary, and CTE is a postmortem diagnosis, making prospective studies difficult. There is growing interest in the genetic influence on head trauma and development of CTE. Apolipoprotein epsilon 4 (APOE-ε4) associates with many neurologic diseases, and consensus on the ε4 allele as a risk factor is lacking. This review investigates the influence of APOE-ε4 on MTBI and CTE. A comprehensive PubMed literature search (1966 to 12 June 2018) identified 24 unique reports on the topic (19 MTBI studies: 8 athletic, 5 military, 6 population-based; 5 CTE studies: 4 athletic and military, 1 leucotomy group). APOE-ε4 genotype is found to associate with outcomes in 4/8 athletic reports, 3/5 military reports, and 5/6 population-based reports following MTBI. Evidence on the association between APOE-ε4 and CTE from case series is equivocal. Refining modalities to aid CTE diagnosis in larger samples is needed in MTBI.

Predicting Fatigue 12 Months after Child Traumatic Brain Injury: Child Factors and Postinjury Symptoms

OBJECTIVES

Fatigue is a common and persisting symptom after childhood brain injury. This study examined whether child characteristics and symptomatology preinjury or 6 months postinjury (pain, sleep, and mood, inattention) predicted fatigue at 12months postinjury.

METHODS

Parents of 79 children (0-18 years) rated fatigue at 12 months after injury on a multidimensional scale (general, sleep/rest, and cognitive). Demographic and clinical data were collected at injury. Parents rated child sleep, pain, physical/motor function, mood, and inattention at injury (preinjury description), and 6 months postinjury. Children were divided into two traumatic brain injury severity groups: mild TBI (n=57) and moderate/severe TBI (n=27). Hierarchical regression models were used to examine (i) preinjury factors and (ii) symptoms 6 months postinjury predictive of fatigue (general, sleep/rest, and cognitive) at 12 months postinjury.

RESULTS

Sleep/rest fatigue was predicted by preinjury fatigue (7% of variance) and psychological symptoms preinjury (10% of variance). General fatigue was predicted by physical/motor symptoms (27%), sleep (10%) and mood symptoms (9%) 6 months postinjury. Sleep/rest fatigue was predicted by physical/motor symptoms (10%), sleep symptoms (13%) and mood symptoms (9%) 6 months postinjury. Cognitive fatigue was predicted by physical/motor symptoms (17%) 6 months postinjury.

CONCLUSIONS

Preinjury fatigue and psychological functioning identified those at greatest risk of fatigue 12 months post-TBI. Predictors of specific fatigue domains at 12 months differed across each of the domains, although consistently included physical/motor function as well as sleep and mood symptoms postinjury. (JINS, 2018, 24, 224-236).

The current state of biomarkers of mild traumatic brain injury

Mild traumatic brain injury (mTBI) is a common occurrence, with over 3 million cases reported every year in the United States. While research into the underlying pathophysiology is ongoing, there is an urgent need for better clinical guidelines that allow more consistent diagnosis of mTBI and ensure safe return-to-play timelines for athletes, nonathletes, and military personnel. The development of a suite of biomarkers that indicate the pathogenicity of mTBI could lead to clinically useful tools for establishing both diagnosis and prognosis. Here, we review the current evidence for mTBI biomarkers derived from investigations of the multifactorial pathology of mTBI. While the current literature lacks the scope and size for clarification of these biomarkers' clinical utility, early studies have identified some promising candidates.

Apolipoprotein E epsilon 4 (APOE-ε4) genotype is associated with decreased 6-month verbal memory performance after mild traumatic brain injury

INTRODUCTION

The apolipoprotein E (APOE) ε4 allele associates with memory impairment in neurodegenerative diseases. Its association with memory after mild traumatic brain injury (mTBI) is unclear.

METHODS

mTBI patients (Glasgow Coma Scale score 13-15, no neurosurgical intervention, extracranial Abbreviated Injury Scale score ≤1) aged ≥18 years with APOE genotyping results were extracted from the Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot (TRACK-TBI Pilot) study. Cohorts determined by APOE-ε4(+/-) were assessed for associations with 6-month verbal memory, measured by California Verbal Learning Test, Second Edition (CVLT-II) subscales: Immediate Recall Trials 1-5 (IRT), Short-Delay Free Recall (SDFR), Short-Delay Cued Recall (SDCR), Long-Delay Free Recall (LDFR), and Long-Delay Cued Recall (LDCR). Multivariable regression controlled for demographic factors, seizure history, loss of consciousness, posttraumatic amnesia, and acute intracranial pathology on computed tomography (CT).

RESULTS

In 114 mTBI patients (APOE-ε4(-)=79; APOE-ε4(+)=35), ApoE-ε4(+) was associated with long-delay verbal memory deficits (LDFR: B = -1.17 points, 95% CI [-2.33, -0.01], p = .049; LDCR: B = -1.58 [-2.63, -0.52], p = .004), and a marginal decrease on SDCR (B = -1.02 [-2.05, 0.00], p = .050). CT pathology was the strongest predictor of decreased verbal memory (IRT: B = -8.49, SDFR: B = -2.50, SDCR: B = -1.85, LDFR: B = -2.61, LDCR: B = -2.60; p < .001). Seizure history was associated with decreased short-term memory (SDFR: B = -1.32, p = .037; SDCR: B = -1.44, p = .038).

CONCLUSION

The APOE-ε4 allele may confer an increased risk of impairment of 6-month verbal memory for patients suffering mTBI, with implications for heightened surveillance and targeted therapies. Acute intracranial pathology remains the driver of decreased verbal memory performance at 6 months after mTBI.

Applying Systems Biology Methodology To Identify Genetic Factors Possibly Associated with Recovery after Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of morbidity and mortality worldwide. It is linked with a number of medical, neurological, cognitive, and behavioral sequelae. The influence of genetic factors on the biology and related recovery after TBI is poorly understood. Studies that seek to elucidate the impact of genetic influences on neurorecovery after TBI will lead to better individualization of prognosis and inform development of novel treatments, which are considerably lacking. Current genetic studies related to TBI have focused on specific candidate genes. The objectives of this study were to use a system biology-based approach to identify biologic processes over-represented with genetic variants previously implicated in clinical outcomes after TBI and identify unique genes potentially related to recovery after TBI. After performing a systematic review to identify genes in the literature associated with clinical outcomes, we used the genes identified to perform a systems biology-based integrative computational analysis to ascertain the interactions between molecular components and to develop models for regulation and function of genes involved in TBI recovery. The analysis identified over-representation of genetic variants primarily in two biologic processes: response to injury (cell proliferation, cell death, inflammatory response, and cellular metabolism) and neurocognitive and behavioral reserve (brain development, cognition, and behavior). Overall, this study demonstrates the use of a systems biology-based approach to identify unique/novel genes or sets of genes important to the recovery process. Findings from this systems biology-based approach provide additional insight into the potential impact of genetic variants on the underlying complex biological processes important to TBI recovery and may inform the development of empirical genetic-related studies for TBI. Future studies that combine systems biology methodology and genomic, proteomic, and epigenetic approaches are needed in TBI.

A systematic review of the association between fatigue and genetic polymorphisms

Fatigue is one of the most common and distressing symptoms, leading to markedly decreased quality of life among a large subset of patients with a variety of disorders. Susceptibility to fatigue may be influenced by genetic factors including single nucleotide polymorphisms (SNPs), especially in the regulatory regions, of relevant genes. To further investigate the association of SNPs with fatigue in various patient populations, a systematic search was conducted on Pubmed, CINAHL, PsycINFO, and Sociological Abstracts Database for fatigue related-terms in combination with polymorphisms or genetic variation-related terms. Fifty papers in total met the inclusion and exclusion criteria for this analysis. These 50 papers were further classified into three subgroups for evaluation: chronic fatigue syndrome (CFS), cancer-related fatigue (CRF) and other disease-related fatigue. SNPs in regulatory pathways of immune and neurotransmitter systems were found to play important roles in the etiologies of CFS, CRF and other disease-related fatigue. Evidence for associations between elevated fatigue and specific polymorphisms in TNFα, IL1b, IL4 and IL6 genes was revealed for all three subgroups of fatigue. We also found CFS shared a series of polymorphisms in HLA, IFN-γ, 5-HT and NR3C1 genes with other disease-related fatigue, however these SNPs (excluding IFN-γ) were not found to be adequately investigated in CRF. Gaps in knowledge related to fatigue etiology and recommendations for future research are further discussed.

Fatigue in the first year after traumatic brain injury: course, relationship with injury severity, and correlates

The objectives of this study were to document the evolution of fatigue in the first year after traumatic brain injury (TBI), and to explore correlates of fatigue. Participants were 210 adults who were hospitalised following a TBI. They completed questionnaires 4, 8, and 12 months post-injury, including the Multidimensional Fatigue Inventory (MFI). Participants with severe TBI presented greater mental and physical fatigue, and reduced activity compared to participants with moderate TBI. For all MFI subscales except reduced motivation, the general pattern was a reduction of fatigue levels over time after mild TBI, an increase of fatigue after severe TBI, and stable fatigue after moderate TBI. Fatigue was significantly associated with depression, insomnia, cognitive difficulties, and pain at 4 months; the same variables and work status at 8 months; and depression, insomnia, cognitive difficulties, and work status at 12 months. These findings suggest that injury severity could have an impact on the course of fatigue in the first year post-TBI. Depression, insomnia, and cognitive difficulties remain strong correlates of fatigue, while for pain and work status the association with fatigue evolves over time. This could influence the development of intervention strategies for fatigue, implemented at specific times for each severity subgroup.

Perceived Social Support and Its Impact on Mental Fatigue in Patients with Mild Traumatic Brain Injury

BACKGROUND

Although mental fatigue was well-recognized as one of the long-term consequences following mild traumatic brain injury (MTBI) that required ongoing support, evidences for the optimal management remained inadequate.

AIMS

To investigate the temporal profile of mental fatigue during the first year after MTBI and examine the impact of perceived social support on the recovery from post-MTBI fatigue.

STUDY DESIGN

Observational case-control study.

METHODS

This study was conducted among post-MTBI patients admitted to the emergency department in a tertiary-care hospital in Sichuan, China. During four waves of assessments at 1 week, 3, 6 and 12 months, mental fatigue was assessed through Mental Fatigue Scale (MFS) whereas social support was assessed by the Multidimensional Scale of Perceived Social Support (MSPSS).

RESULTS

There were 65.1%, 37.1%, 34.8% and 32.5% individuals being identified as those with mental fatigue at 1 week, 3, 6 and 12 months, respectively. The scores of MFS didn't change substantially since 3 months post-injury. Compared to non-fatigued MTBI patients, those with long-lasting post- MTBI fatigue reported extremely lower level of perceived social support. Moreover, improved social support at 1 week was negatively associated with the occurrence of long-lasting fatigue.

CONCLUSION

Sufficient social support could significantly decrease the occurrence of long-lasting mental fatigue among MTBI cases. It seemed of great importance to modify the emphasis of rehabilitation to include assessment and improvement of perceived social support at earlier stages after injury.

Mindfulness-based stress reduction (MBSR) improves long-term mental fatigue after stroke or traumatic brain injury

OBJECTIVE

Patients who suffer from mental fatigue after a stroke or traumatic brain injury (TBI) have a drastically reduced capacity for work and for participating in social activities. Since no effective therapy exists, the aim was to implement a novel, non-pharmacological strategy aimed at improving the condition of these patients.

METHODS

This study tested a treatment with mindfulness-based stress reduction (MBSR). The results of the programme were evaluated using a self-assessment scale for mental fatigue and neuropsychological tests. Eighteen participants with stroke and 11 with TBI were included. All the subjects were well rehabilitated physically with no gross impairment to cognitive functions other than the symptom mental fatigue. Fifteen participants were randomized for inclusion in the MBSR programme for 8 weeks, while the other 14 served as controls and received no active treatment. Those who received no active treatment were offered MBSR during the next 8 weeks.

RESULTS

Statistically significant improvements were achieved in the primary end-point--the self-assessment for mental fatigue--and in the secondary end-point--neuropsychological tests; Digit Symbol-Coding and Trail Making Test.

CONCLUSION

The results from the present study show that MBSR may be a promising non-pharmacological treatment for mental fatigue after a stroke or TBI.

Does Apolipoprotein E Play a Role in Outcome After Severe Traumatic Brain Injury?

There is mixed evidence linking adverse outcomes after traumatic brain injury to the presence of the ε4 allele of the apolipoprotein gene (APOE). Further, there has been limited investigation of the role of APOE in populations who have sustained severe brain injuries. In this study, 100 individuals aged 16 to 65 years with a severe to extremely severe traumatic brain injury were recruited prospectively from an inpatient rehabilitation unit. APOE genotypes were determined, and demographic and clinical data were collected by blind assessors at 6 months postinjury. Sixty-nine participants who were divided into an acute (less than 12 months postinjury) and chronic (greater than 12 months) groups also completed neuropsychological assessments testing various domains of memory, attention and problem-solving at follow-up. No significant differences in injury severity, cognitive or functional outcome were found between individuals with the ε4 allele and those without at either time postinjury. This finding is consistent with other recent data that has questioned the role of APOE status as a factor in recovery from TBI.

Genetics and outcomes after traumatic brain injury (TBI): what do we know about pediatric TBI?

Human genetic association studies in individuals with traumatic brain injury (TBI) have increased rapidly over the past few years. Recently, several review articles evaluated the association of genetics with outcomes after TBI. However, almost all of the articles discussed in these reviews focused on adult TBI. The primary objective of this review is to gain a better understanding of which genes and/or genetic polymorphisms have been evaluated in pediatric TBI. Our initial search identified 113 articles. After review of these articles only 5 genetic association studies specific to pediatric TBI were identified. All five of these studies evaluated the apolipoprotein (APOE) gene. The study design and methods of these identified papers will be discussed. An additional search was then performed to evaluate genes beyond APOE that have been evaluated in adult TBI; findings from these studies are highlighted. Larger genetic studies will need to be performed in the future to better elucidate the association of APOE and other genes with outcomes after TBI in children. There is great potential to utilized genetic information to inform prognosis and management after TBI in children; however, we have much work ahead of us to reach the goal of individualized management.

Mild traumatic brain injury and fatigue: a prospective longitudinal study

PRIMARY OBJECTIVE

To examine fatigue prevalence, severity, predictors and co-variates over 6 months post-mild traumatic brain injury (MTBI).

RESEARCH DESIGN

Longitudinal prospective study including 263 adults with MTBI.

PROCEDURES

Participants completed the Fatigue Severity Scale (FSS), Rivermead Post-concussion Symptoms Questionnaire (RPSQ), Hospital Anxiety and Depression Scale (HADS) and the Short Form 36 Health Survey-Version 2 (SF-36v2). Complete data were available for 159 participants. Key measures; prevalence--RPSQ Item 6: severity--FSS. The effect of time on fatigue prevalence and severity was examined using ANOVA. Multiple regression analysis identified statistically significant covariates.

MAIN OUTCOMES AND RESULTS

Post-MTBI fatigue prevalence was 68%, 38% and 34% at 1 week, 3 and 6 months, respectively. There was a strong effect for time over the first 3 months and moderate-to-high correlations between fatigue prevalence and severity. Early fatigue strongly predicted later fatigue; depression, but not anxiety was a predictor. Fatigue was seen as laziness by family or friends in 30% of cases.

CONCLUSIONS

Post-MTBI fatigue is a persistent post-concussion symptom, exacerbated by depression but not anxiety. It diminishes in the first 3 months and then becomes relatively stable, suggesting the optimum intervention placement is at 3 months or more post-MTBI.

Rehabilitation in the patient with mild traumatic brain injury

Traumatic brain injury (TBI) has garnered increased public attention in the past several years because of high-profile athletes with possible long-term effects of their injuries as well as large numbers of returning combat veterans injured by blast explosions. Most of these injuries are mild in nature and require no specific surgical treatment but may benefit from brief rehabilitation interventions. To appropriately rehabilitate patients with mild traumatic brain injury (mTBI), one must fully understand its clinical course and the factors that accelerate or delay recovery. Education is the centerpiece of mTBI treatment and should be included in the rehabilitation plan. When devising the rehabilitation plan, the neurologist should take into account the goals of the patient and establish a reasonable time frame for treatment paralleling the expected recovery course. Cognitive and vestibular functions are commonly affected after mTBI and are particularly responsive to rehabilitation interventions. Vocational rehabilitation and community reentry planning are aspects of the global rehabilitation plan that should not be neglected. Combat-injured veterans with mTBI present unique challenges to the rehabilitation team, and assessment of these patients often needs to include assessment of psychological function.

Gene expression profiling for discovery of novel targets in human traumatic brain injury

Several clinical trials have failed to demonstrate a significant effect on outcome following human traumatic brain injury (TBI) despite promising results obtained in preclinical animal studies. These failures may be due in part to a misinterpretation of the findings obtained in preclinical animal models of TBI, a misunderstanding of the complexity of the human response to TBI, limited knowledge about the biological pathways that interact to contribute to good and bad outcomes after brain injury, and the effects of genomic variability and environment on individual recovery. Recent publications suggest that data obtained from gene expression profiling studies of complex neurological diseases such as stroke, multiple sclerosis (MS), Alzheimer's and Parkinson's may contribute to a more informed understanding of what affects outcome following TBI. These data may help to bridge the gap between successful preclinical studies and negative clinical trials in humans to reveal novel targets for therapy. Gene expression profiling has the capability to identify biomarkers associated with response to TBI, elucidate complex genetic interactions that may play a role in outcome following TBI, and reveal biological pathways related to brain health. This review highlights the current state of the literature on gene expression profiling for neurological disease and discusses its ability to aid in unraveling the variable human response to TBI and the potential for it to offer treatment strategies in an area where we currently have limited therapeutic options primarily based on supportive care.

The apolipoprotein E ε4 allele and outcome in severe traumatic brain injury treated by an intracranial pressure–targeted therapy

Object

In this paper, the authors' goal was to study the influence of the apolipoprotein E ε4 allele on the clinical outcome in patients treated for severe traumatic brain injury (TBI) with an intracranial pressure (ICP)–targeted therapy based on the Lund concept.

Methods

The authors conducted a prospective double-blinded randomized trial in which they examined patients with severe TBI. Inclusion criteria consisted of a Glasgow Coma Scale (GCS) score ≤ 8 at the time of intubation and sedation, patient age between 15 and 70 years, an initial cerebral perfusion pressure > 10 mm Hg, and arrival to the hospital < 24 hours after trauma. Blood samples for the analysis of apolipoprotein E allele types were collected. Independent staff members evaluated outcomes by obtaining Glasgow Outcome Scale (GOS) scores at 3, 12, and 24 months.

Results

The occurrence of the ε4 allele was analyzed in 46 patients (mean age 35 ± 2.2 years with a median GCS score of 6 [range 3–8]). The ε4 allele was present in 39.1% of the patients. The ICP, cerebral perfusion pressure, and injury severity score were not statistically significantly different between the groups. The median GOS score at 3 months was 3.5, and at 12 and 24 months was 4 (range 1–5). Except for the GOS score at 3 months, which was dichotomized as favorable (GOS Score 4 or 5) and unfavorable (GOS Scores 1–3), no statistically significant differences in outcome, irrespective of GOS dichotomization used, were found between the patients with the ε4 allele and those without. The presence of the ε4 allele did not predict for clinical outcome, but GCS and ICP did.

Conclusions

The presence of ε4 is not associated with long-term clinical outcome in patients with severe TBI treated with an ICP targeted therapy, based on the Lund concept.

Apolipoprotein E4 as a predictor of outcomes in pediatric mild traumatic brain injury

The epsilon4 allele of the apolipoprotein E (APOE) gene has been linked to negative outcomes among adults with traumatic brain injury (TBI) across the spectrum of severity, with preliminary evidence suggesting a similar pattern among children. This study investigated the relationship of the APOE epsilon4 allele to outcomes in children with mild TBI. Participants in this prospective, longitudinal study included 99 children with mild TBI between the ages of 8 and 15 recruited from consecutive admissions to Emergency Departments at two large children's hospitals. Outcomes were assessed acutely in the Emergency Department and at follow-ups at 2 weeks, 3 months, and 12 months post-injury. Among the 99 participants, 28 had at least one epsilon4 allele. Children with and without an epsilon4 allele did not differ demographically. Children with an epsilon4 allele were significantly more likely than those without an epsilon4 allele to have a Glasgow Coma Scale score of less than 15, but the groups did not differ on any other measures of injury severity. Those with an epsilon4 allele exhibited better performance than children without an epsilon4 allele on a test of constructional skill, but the groups did not differ on any other neuropsychological tests. Children with and without an epsilon4 allele also did not differ on measures of post-concussive symptoms. Overall, the findings suggest that the APOE epsilon4 allele is not consistently related to the outcomes of mild TBI in children.

Baseline predictors of fatigue 1 year after mild head injury

OBJECTIVE

To compare reports of fatigue 12 months after minor trauma by participants with mild head injury (MHI) with those with other injury, and identify injury and baseline predictors of fatigue.

DESIGN

An inception cohort study of participants with MHI and other nonhead injuries recruited from and interviewed at the emergency department (ED), with a follow-up telephone interview at 12 months.

SETTING

Level II community hospital ED.

PARTICIPANTS

Participants (n=58) with MHI and loss of consciousness (LOC) of 30 minutes or less and/or posttraumatic amnesia (PTA) less than 24 hours, 173 with MHI but no PTA/LOC, and 128 with other mild nonhead injuries.

INCLUSION CRITERIA

age 18 years or older, within 24 hours of injury, Glasgow Coma Scale score of 13 or higher, and discharge from the ED.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Medical Outcomes Study 36-Item Short-Form Health Survey Vitality subscale.

RESULTS

Significant predictors of fatigue severity at 12 months were baseline fatigue, having seen a counselor for a mental health issue, medical disability, marital status, and in some stage of litigation. Injury type was not a significant predictor.

CONCLUSIONS

Fatigue severity 12 months after injury is associated with baseline characteristics and not MHI. Clinicians should be cautious about attributing persisting fatigue to MHI without comprehensive consideration of other possible etiologic factors.

Psychological and biological correlates of fatigue after mild-to-moderate traumatic brain injury

Relationships between chronic perceived stress, cortisol response (area under the curve) and posttraumatic brain injury fatigue were examined with persons from outpatient settings. Seventy-five injured persons with traumatic brain injury and their relatives/significant others participated in this cross-sectional study. Using interviews and self-reported data from the Neurofunctional Behavioral Inventory, the Perceived Stress Scale, the Profile of Mood States-Fatigue subscale, the McGill Pain Scale, as well as self-collection of salivary cortisol over a 12-hour period (N = 50), we found that perceived chronic stress explained 40% of the variance in fatigue until depressive symptoms and pain were in the model. Hypocortisolemia was evident. Somatic symptom frequency and perceived chronic stress represented 50% of the variability in post-TBI fatigue. Fatigue and stress management interventions, as suggested in the Centers for Disease Control Acute Concussion guidelines, may be beneficial in reducing this common symptom.