Variants of SLC6A4 in depression risk following severe TBI

Effectiveness of Pharmacotherapy for Depression after Adult Traumatic Brain Injury: an Umbrella Review

Symptoms of depression are common following traumatic brain injury (TBI), impacting survivors' ability to return to work, participate in leisure activities, and placing strain on relationships. Depression symptoms post TBI are often managed with pharmacotherapy, however, there is little research evidence to guide clinical practice. There have been a number of recent systematic reviews examining pharmacotherapy for post TBI depression. The aim of this umbrella review was to synthesize systematic reviews and meta-analyses of the effectiveness of pharmacotherapy for the management of post TBI depression in adults. Eligible reviews examined any pharmacotherapy against any comparators, for the treatment of depression in adults who had sustained TBI. Seven databases were searched, with additional searching of online journals, Research Gate, Google Scholar and the TRIP Medical Database to identify published and unpublished systematic reviews and meta-analyses in English up to May 2020. A systematic review of primary studies available between March 2018 and May 2020 was also conducted. Evidence quality was assessed using Joanna Briggs Institute Critical Appraisal Instruments. The results are presented as a narrative synthesis. Twenty-two systematic reviews were identified, of which ten reviews contained a meta-analysis. No new primary studies were identified in the systematic review. There was insufficient high quality and methodologically rigorous evidence to recommend prescribing any specific drug or drug class for post TBI depression. The findings do show, however, that depression post TBI is responsive to pharmacotherapy in at least some individuals. Recommendations for primary studies, systematic reviews and advice for prescribers is provided. Review Registration PROSPERO (CRD42020184915).

The Effect of Antidepressants on Depression After Traumatic Brain Injury: A Meta-analysis

OBJECTIVE

Following traumatic brain injury (TBI), depressive symptoms are common and may influence recovery. We performed a meta-analysis to estimate the benefit of antidepressants following TBI and compare the estimated effects between antidepressants and placebo.

PARTICIPANTS

Multiple databases were searched to find prospective pharmacological treatment studies of major depressive disorder (MDD) in adults following TBI.

MAIN MEASURES

Effect sizes for antidepressant medications in patients with TBI were calculated for within-subjects designs that examined change from baseline after receiving medical treatment and treatment/placebo designs that examined the differences between the antidepressants and placebo groups.

DESIGN

A random-effects model was used for both analyses.

RESULTS

Of 1028 titles screened, 11 were included. Pooled estimates showed nonsignificant difference in reduction of depression scores between medications and placebo (standardized mean difference of 5 trials = -0.3; 95% CI, -0.6 to 0.0; I = 17%), and a significant reduction in depression scores for individuals after pharmacotherapy (mean change = -11.2; 95% CI, -14.7 to -7.6 on the Hamilton Depression Scale; I = 87%).

CONCLUSIONS

This meta-analysis found no significant benefit of antidepressant over placebo in the treatment of MDD following TBI. Pooled estimates showed a high degree of bias and heterogeneity. Prospective studies on the impact of antidepressants in well-defined cohorts of TBI patients are warranted.

Genetic drivers of cerebral blood flow dysfunction in TBI: a speculative synthesis

Cerebral autoregulatory dysfunction after traumatic brain injury (TBI) is strongly linked to poor global outcome in patients at 6 months after injury. However, our understanding of the drivers of this dysfunction is limited. Genetic variation among individuals within a population gives rise to single-nucleotide polymorphisms (SNPs) that have the potential to influence a given patient's cerebrovascular response to an injury. Associations have been reported between a variety of genetic polymorphisms and global outcome in patients with TBI, but few studies have explored the association between genetic variants and cerebrovascular function after injury. In this Review, we explore polymorphisms that might play an important part in cerebral autoregulatory capacity after TBI. We outline a variety of SNPs, their biological substrates and their potential role in mediating cerebrovascular reactivity. A number of candidate polymorphisms exist in genes that are involved in myogenic, endothelial, metabolic and neurogenic vascular responses to injury. Furthermore, polymorphisms in genes involved in inflammation, the central autonomic response and cortical spreading depression might drive cerebrovascular reactivity. Identification of candidate genes involved in cerebral autoregulation after TBI provides a platform and rationale for further prospective investigation of the link between genetic polymorphisms and autoregulatory function.

Genetic Influences on Patient-Oriented Outcomes in Traumatic Brain Injury: A Living Systematic Review of Non-Apolipoprotein E Single-Nucleotide Polymorphisms

There is a growing literature on the impact of genetic variation on outcome in traumatic brain injury (TBI). Whereas a substantial proportion of these publications have focused on the apolipoprotein E (APOE) gene, several have explored the influence of other polymorphisms. We undertook a systematic review of the impact of single-nucleotide polymorphisms (SNPs) in non–apolipoprotein E (non-APOE) genes associated with patient outcomes in adult TBI). We searched EMBASE, MEDLINE, CINAHL, and gray literature from inception to the beginning of August 2017 for studies of genetic variance in relation to patient outcomes in adult TBI. Sixty-eight articles were deemed eligible for inclusion into the systematic review. The SNPs described were in the following categories: neurotransmitter (NT) in 23, cytokine in nine, brain-derived neurotrophic factor (BDNF) in 12, mitochondrial genes in three, and miscellaneous SNPs in 21. All studies were based on small patient cohorts and suffered from potential bias. A range of SNPs associated with genes coding for monoamine NTs, BDNF, cytokines, and mitochondrial proteins have been reported to be associated with variation in global, neuropsychiatric, and behavioral outcomes. An analysis of the tissue, cellular, and subcellular location of the genes that harbored the SNPs studied showed that they could be clustered into blood–brain barrier associated, neuroprotective/regulatory, and neuropsychiatric/degenerative groups. Several small studies report that various NT, cytokine, and BDNF-related SNPs are associated with variations in global outcome at 6–12 months post-TBI. The association of these SNPs with neuropsychiatric and behavioral outcomes is less clear. A definitive assessment of role and effect size of genetic variation in these genes on outcome remains uncertain, but could be clarified by an adequately powered genome-wide association study with appropriate recording of outcomes.

Employment Stability in the First 5 Years After Moderate-to-Severe Traumatic Brain Injury

OBJECTIVE

To characterize employment stability and identify predictive factors of employment stability in working-age individuals after moderate-to-severe traumatic brain injury (TBI) that may be clinically addressed.

DESIGN

Longitudinal observational study of an inception cohort from the Traumatic Brain Injury Model Systems National Database (TBIMS-NDB) using data at years 1, 2, and 5 post-TBI.

SETTING

Inpatient rehabilitation centers with telephone follow-up.

PARTICIPANTS

Individuals enrolled in the TBIMS-NDB since 2001, aged 18-59, with employment data at 2 or more follow-up interviews at years 1, 2, and 5 (N=5683).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Employment stability, categorized using post-TBI employment data as no paid employment (53.25%), stably (27.20%), delayed (10.24%), or unstably (9.31%) employed.

RESULTS

Multinomial regression analyses identified predictive factors of employment stability, including younger age, white race, less severe injuries, preinjury employment, higher annual earnings, male sex, higher education, transportation independence postinjury, and no anxiety or depression at 1 year post-TBI.

CONCLUSIONS

Employment stability serves as an important measure of productivity post-TBI. Psychosocial, clinical, environmental, and demographic factors predict employment stability post-TBI. Notable predictors include transportation independence as well as the presence of anxiety and depression at year 1 post-TBI as potentially modifiable intervention targets.

Placebo Effects in Traumatic Brain Injury

In recent years, several randomized controlled trials evaluating pharmaceutical treatments for traumatic brain injury (TBI) have failed to demonstrate efficacy over placebo, with both active and placebo arms improving at comparable rates. These findings could be viewed in opposing ways, suggesting on the one hand failure of the tested outcome, but on the other, representing evidence of robust placebo effects in TBI. In this article, we examine several of the primary psychological processes driving placebo effects (verbal suggestion, cognitive re-framing, interpersonal interactions, conditioning, therapeutic alliance, anxiety reduction) as well as placebo neurobiology (top-down cortical regulation, reward system activation, dopaminergic and serotonergic neurotransmission). We then extrapolate from the literature to explore whether something inherent in TBI makes it particularly responsive to placebos. Viewed as such here, placebos may indeed represent a powerful and effective treatment for a variety of post-TBI complaints.

Depression in the First Year after Traumatic Brain Injury

The aims of this study were to document the frequency of major and minor depressive episodes in the first year after traumatic brain injury (TBI), taking into account TBI severity and pre-morbid history of major depression, and to describe trajectories of depressive episodes. Participants were 227 adults who were hospitalized post-TBI (76% male; mean age = 41 years; 50% mild, 33% moderate, and 17% severe TBI). Major and minor depressive episodes were assessed with the Mini International Neuropsychiatric Interview at three time points (4, 8, and 12 months after TBI). Overall, 29% of participants had a major depressive episode in at least one of the three assessments, with fairly stable rates across assessments. Participants with mild TBI were more likely than those with moderate/severe TBI to be diagnosed with major depression, as were individuals with a positive pre-morbid history of depression compared to those without such history. In addition, 13% of participants had a minor depressive episode in at least one of the three assessments. Rates of minor depression significantly decreased from 4 to 8-12 months post-injury. Results also revealed a wide variety of trajectories of depressive episodes across assessments. Of note, 52% of major depression cases still fulfilled diagnostic criteria 4 months later, whereas 38% of minor depression cases deteriorated to major depression at the following assessment. These findings suggest that depression is highly prevalent after TBI, and monitoring of patients with subthreshold depressive symptoms is warranted in order to prevent the development of full-blown major depressive episodes.

Effects of Depression and Antidepressant Use on Cognitive Deficits and Functional Cognition Following Severe Traumatic Brain Injury

OBJECTIVE

To use a Rehabilomics framework to evaluate relations hips between post-traumatic brain injury (TBI) depression (PTD) and potential associated factors, including antidepressant use, on cognitive recovery following severe TBI.

PARTICIPANTS

Severe TBI survivors (n = 154), recruited from a level 1 trauma center.

DESIGN

Prospective cohort study with assessments at 6 and 12 months postinjury.

MAIN MEASURES

Patient Health Questionnaire-9 (PTD symptoms); cognitive composite score from a neuropsychological assessment battery (cognitive impairment); and Functional Independence Measure-Cognition (FIM-Cog, self-reported functional cognition).

RESULTS

Individuals with and without PTD did not differ with respect to cognitive impairment. However, antidepressant use, regardless of PTD status, was associated with cognitive impairment. Individuals with PTD reported lower FIM-Cog scores at both time points compared with those without PTD. In a post hoc longitudinal analysis, individuals with late-onset PTD had worse cognitive impairment.

CONCLUSION

These results suggest that antidepressant use impairs cognition among individuals without PTD. Also, PTD did not directly affect cognitive impairment but may affect functional cognitive limitations through self-evaluation and apathy/motivation factors.

A Dopamine Pathway Gene Risk Score for Cognitive Recovery Following Traumatic Brain Injury: Methodological Considerations, Preliminary Findings, and Interactions With Sex

OBJECTIVES

With evidence of sexual dimorphism involving the dopamine (DA)-pathway, and the importance of DA pathways in traumatic brain injury (TBI) recovery, we hypothesized that sex × DA-gene interactions may influence cognition post-TBI.

PARTICIPANTS

Adult survivors of severe TBI (n = 193) consecutively recruited from a level 1 trauma center.

DESIGN

Risk allele assignments were made for multiple DA pathway genes using a sex-specific stratified approach. Genetic risk alleles, and their impacts on cognition, were assessed at 6 and 12 months postinjury using unweighted, semiweighted, and weighted gene risk score (GRS) approaches.

MAIN MEASURES

A cognitive composite score generated from 8 standardized neuropsychological tests targeting multiple cognitive domains.

RESULTS

A significant sex × gene interaction was observed at 6 and 12 months for ANKK1 rs1800497 (6M: P = .002, 12M: P = .001) and COMT rs4680 (6M: P = .048; 12M: P = .004); DRD2 rs6279 (P = .001) and VMAT rs363226 (P = .043) genotypes were independently associated with cognition at 6 months, with trends for a sex × gene interaction at 12 months. All GRS methods were significant predictors of cognitive performance in multivariable models. Weighted GRS multivariate models captured the greatest variance in cognition: R = 0.344 (6 months); R = 0.441 (12 months), significantly increasing the variance captured from the base prediction models.

CONCLUSIONS

A sex-specific DA-pathway GRS may be a valuable tool when predicting cognitive recovery post-TBI. Future work should validate these findings and explore how DA-pathway genetics may guide therapeutic intervention.

Genetic Variation in the Vesicular Monoamine Transporter: Preliminary Associations With Cognitive Outcomes After Severe Traumatic Brain Injury

INTRODUCTION

Traumatic brain injury (TBI) frequently results in impaired cognition, a function that can be modulated by monoaminergic signaling. Genetic variation among monoaminergic genes may affect post-TBI cognitive performance. The vesicular monoamine transporter-2 (VMAT2) gene may be a novel source of genetic variation important for cognitive outcomes post-TBI given VMAT2's role in monoaminergic neurotransmission.

OBJECTIVE

To evaluate associations between VMAT2 variability and cognitive outcomes post-TBI.

METHODS

We evaluated 136 white adults with severe TBI for variation in VMAT2 using a tagging single nucleotide polymorphism (tSNP) approach (rs363223, rs363226, rs363251, and rs363341). We show genetic variation interacts with assessed cognitive impairment (cognitive composite [Comp-Cog] T-scores) to influence functional cognition (functional independence measure cognitive [FIM-Cog] subscale] 6 and 12 months postinjury.

RESULTS

Multivariate analyses at 6 months postinjury showed rs363226 genotype was associated with Comp-Cog (P = .040) and interacted with Comp-Cog to influence functional cognition (P < .001). G-homozygotes had the largest cognitive impairment, and their cognitive impairment had the greatest adverse effect on functional cognition.

DISCUSSION

We provide the first evidence that genetic variation within VMAT2 is associated with cognitive outcomes after TBI. Further work is needed to validate this finding and elucidate mechanisms by which genetic variation affects monoaminergic signaling, mediating differences in cognitive outcomes.

The effects of post-traumatic depression on cognition, pain, fatigue, and headache after moderate-to-severe traumatic brain injury: a thematic review

BACKGROUND

Post-traumatic depression (PTD) is one of the most common secondary complications to develop after moderate-to-severe traumatic brain injury (TBI). However, it rarely manifests singularly, and often co-occurs with other common TBI impairments.

OBJECTIVE

The objective of this thematic review is to evaluate studies examining the relationships between PTD and cognition, fatigue, pain, and headache among individuals with moderate-to-severe TBI.

RESULTS

We reviewed 16 studies examining the relationship between PTD and cognition (five articles), fatigue (five articles), pain (four articles), and headache (two articles). Two studies failed to identify the significant associations between PTD and neuropsychological test performance, while one study found a positive association. Two other studies found that early PTD was associated with later executive dysfunction. Studies on fatigue suggest it is a cause, not consequence, of PTD. Individuals with PTD tended to report more pain than those without PTD. Studies examining relationships between PTD and post-traumatic headache were equivocal.

CONCLUSIONS

Studies evaluating the effects of PTD on common TBI impairments have yielded mixed results. Evidence suggests PTD precedes the development of executive dysfunction, and a strong link exists between fatigue and PTD, with fatigue preceding PTD. Future prospective studies evaluating PTD relationships to pain and headache are warranted to elucidate causality.

The pharmacogenomics of severe traumatic brain injury

Pharmacotherapy for traumatic brain injury (TBI) is focused on resuscitation, prevention of secondary injury, rehabilitation and recovery. Pharmacogenomics may play a role in TBI for predicting therapies for sedation, analgesia, seizure prevention, intracranial pressure-directed therapy and neurobehavioral/psychiatric symptoms. Research into genetic predictors of outcomes and susceptibility to complications may also help clinicians to tailor therapeutics for high-risk individuals. Additionally, the expanding use of genomics in the drug development pipeline has provided insight to novel investigational and repurposed medications that may be useful in the treatment of TBI and its complications. Genomics in the context of treatment and prognostication for patients with TBI is a promising area for clinical progress of pharmacogenomics.

A narrative literature review of depression following traumatic brain injury: prevalence, impact, and management challenges

Depression is one of the most common conditions to emerge after traumatic brain injury (TBI), and despite its potentially serious consequences it remains undertreated. Treatment for post-traumatic depression (PTD) is complicated due to the multifactorial etiology of PTD, ranging from biological pathways to psychosocial adjustment. Identifying the unique, personalized factors contributing to the development of PTD could improve long-term treatment and management for individuals with TBI. The purpose of this narrative literature review was to summarize the prevalence and impact of PTD among those with moderate to severe TBI and to discuss current challenges in its management. Overall, PTD has an estimated point prevalence of 30%, with 50% of individuals with moderate to severe TBI experiencing an episode of PTD in the first year after injury alone. PTD has significant implications for health, leading to more hospitalizations and greater caregiver burden, for participation, reducing rates of return to work and affecting social relationships, and for quality of life. PTD may develop directly or indirectly as a result of biological changes after injury, most notably post-injury inflammation, or through psychological and psychosocial factors, including pre injury personal characteristics and post-injury adjustment to disability. Current evidence for effective treatments is limited, although the strongest evidence supports antidepressants and cognitive behavioral interventions. More personalized approaches to treatment and further research into unique therapy combinations may improve the management of PTD and improve the health, functioning, and quality of life for individuals with TBI.

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.

What are the complications and emerging strategies for preventing depression following traumatic brain injury?

INTRODUCTION

Depression is a common and disabling complication of traumatic brain injury (TBI). The high rates of post-TBI depression (PTBID) make this condition an important candidate for selective preventive interventions. Areas covered: The authors recently reported on the efficacy of sertraline, a selective serotonin reuptake inhibitor (SSRI), for the prevention of new cases of depression in the first six months after TBI. The authors review this and other studies on preventive strategies in PTBID as ascertained from a PubMed and citation search. The potential complications and barriers to the implementation of pharmacological prevention in patients with TBI are also discussed. Expert commentary: The prevention of depression in patients with TBI has received little attention relative to other medical conditions. Future studies are needed to confirm the benefit of SSRIs and investigate other pharmacological and non-pharmacological interventions, including in special groups of patients at greater risk of developing PTBID.

Conceptual model and cluster analysis of behavioral symptoms in two cohorts of adults with traumatic brain injuries

INTRODUCTION

Behavioral changes often occur after moderate-to-severe traumatic brain injury (TBI) and can lead to poor health, psychosocial functioning, and quality of life. Challenges in evaluating these behaviors often result from the complexity and variability in the way they are conceptualized and defined. We propose and test a conceptual model that is specific to behavioral symptoms after TBI, to serve as a basis for better assessment and treatment. We hypothesized that clusters of individuals, with unique emotional, cognitive, and behavioral characteristics, would emerge that would illustrate this conceptual model.

METHODS

We conducted model-based cluster analyses in two cohorts, 6-months post-injury (n = 79) and >6 months post-injury (n = 62), of adults with moderate-to-severe TBI to explore the face validity of our conceptual model by evaluating how participants clustered with regard to emotional (Patient Health Questionnaire 9, Positive and Negative Affect Schedule), cognitive (neuropsychological test battery), and frontal behavioral (Frontal Systems Behavior Scale) symptoms.

RESULTS

In each cohort, unique clusters of participants emerged that differed significantly with regard to emotional state, cognition, and behavior (ps<.05). Those 6-months post-injury clustered along a general continuum of symptom severity in emotional and behavioral symptom domains, from no impairment to severe impairment. Clusters in the chronic cohort (>6 months) demonstrated a more complex pattern of symptoms; the most severe behavioral symptoms occurred in the context of severe emotional symptoms, even in the absence of cognitive impairment. However, problematic behavioral symptoms were also present in the context of severe cognitive impairment, even in the absence of emotional symptoms.

CONCLUSIONS

Emotional, cognitive, and behavioral characteristics were represented as expected, based on the proposed conceptual model of behavior. This conceptual model provides the basis for evaluating behavioral changes after moderate-to-severe TBI and identifying modifiable targets and relevant subpopulations for behavioral intervention, with the goal of improved evidence-based personalized medicine for this population.

Posttraumatic Brain Injury Cognitive Performance Is Moderated by Variation Within ANKK1 and DRD2 Genes

OBJECTIVE

As dopamine neurotransmission impacts cognition, we hypothesized that variants in the linked dopamine D2 receptor (DRD2) and ankyrin repeat and kinase domain (ANKK1) genes might account for some individual variability in cognitive recovery following traumatic brain injury (TBI).

PARTICIPANTS

Prospective cohort of 108 survivors of severe TBI, recruited consecutively from a level 1 trauma center.

DESIGN

We examined relationships between DRD2 genetic variation and functional recovery at 6 and 12 months post-TBI.

MAIN MEASURES

Cognitive performance was evaluated using 8 neuropsychological tests targeting different cognitive domains. An overall cognitive composite was developed using normative data. We also assessed functional cognition, depression status, and global outcome. Subjects were genotyped for 6 DRD2 tagging single-nucleotide polymorphisms and Taq1A within ANKK1.

RESULTS

ANKK1 Taq1A heterozygotes performed better than homozygotes across several cognitive domains at both time points postinjury. When adjusting for age, Glasgow Coma Scale score, and education, the Taq1A (ANKK1) and rs6279 (DRD2) variants were associated with overall composite scores at 6 months post-TBI (P = .0453 and P = .0452, respectively). At 12 months, only Taq1A remained a significant genetic predictor of cognition (P = .0128). Following multiple-comparisons correction, there were no significant associations between examined genetic variants and functional cognition, depression status, and global outcome.

CONCLUSION

These data suggest that genetic variation within DRD2 influences cognitive recovery post-TBI. Understanding genetic influences on dopaminergic systems post-TBI may impact current treatment paradigms.

Catecholaminergic based therapies for functional recovery after TBI

Among the many pathophysiologic consequences of traumatic brain injury are changes in catecholamines, including dopamine, epinephrine, and norepinephrine. In the context of TBI, dopamine is the one most extensively studied, though some research exploring epinephrine and norepinephrine have also been published. The purpose of this review is to summarize the evidence surrounding use of drugs that target the catecholaminergic system on pathophysiological and functional outcomes of TBI using published evidence from pre-clinical and clinical brain injury studies. Evidence of the effects of specific drugs that target catecholamines as agonists or antagonists will be discussed. Taken together, available evidence suggests that therapies targeting the catecholaminergic system may attenuate functional deficits after TBI. Notably, it is fairly common for TBI patients to be treated with catecholamine agonists for either physiological symptoms of TBI (e.g. altered cerebral perfusion pressures) or a co-occuring condition (e.g. shock), or cognitive symptoms (e.g. attentional and arousal deficits). Previous clinical trials are limited by methodological limitations, failure to replicate findings, challenges translating therapies to clinical practice, the complexity or lack of specificity of catecholamine receptors, as well as potentially counfounding effects of personal and genetic factors. Overall, there is a need for additional research evidence, along with a need for systematic dissemination of important study details and results as outlined in the common data elements published by the National Institute of Neurological Diseases and Stroke. Ultimately, a better understanding of catecholamines in the context of TBI may lead to therapeutic advancements. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Predictors of Neurocognitive Syndromes in Combat Veterans

Traumatic brain injury, depression and posttraumatic stress disorder (PTSD) are neurocognitive syndromes often associated with impairment of physical and mental health, as well as functional status. These syndromes are also frequent in military service members (SMs) after combat, although their presentation is often delayed until months after their return. The objective of this prospective cohort study was the identification of independent predictors of neurocognitive syndromes upon return from deployment could facilitate early intervention to prevent disability. We completed a comprehensive baseline assessment, followed by serial evaluations at three, six, and 12 months, to assess for new-onset PTSD, depression, or postconcussive syndrome (PCS) in order to identify baseline factors most strongly associated with subsequent neurocognitive syndromes. On serial follow-up, seven participants developed at least one neurocognitive syndrome: five with PTSD, one with depression and PTSD, and one with PCS. On univariate analysis, 60 items were associated with syndrome development at p < 0.15. Decision trees and ensemble tree multivariate models yielded four common independent predictors of PTSD: right superior longitudinal fasciculus tract volume on MRI; resting state connectivity between the right amygdala and left superior temporal gyrus (BA41/42) on functional MRI; and single nucleotide polymorphisms in the genes coding for myelin basic protein as well as brain-derived neurotrophic factor. Our findings require follow-up studies with greater sample size and suggest that neuroimaging and molecular biomarkers may help distinguish those at high risk for post-deployment neurocognitive syndromes.

Pilot feasibility of an mHealth system for conducting ecological momentary assessment of mood-related symptoms following traumatic brain injury

OBJECTIVE

This study assessed pilot feasibility and validity of a mobile health (mHealth) system for tracking mood-related symptoms after traumatic brain injury (TBI).

DESIGN

A prospective, repeated measures design was used to assess compliance with daily ecological momentary assessments (EMA) conducted via a smartphone application over an 8-week period.

METHODS

An mHealth system was developed specifically for individuals with TBI and utilized previously validated tools for depressive and anxiety symptoms (Patient Health Questionnaire-9, Generalized Anxiety Disorder-7). Feasibility was assessed in 20 community-dwelling adults with TBI via an assessment of compliance, satisfaction and usability of the smartphone applications. The authors also developed and implemented a clinical patient safety management mechanism for those endorsing suicidality.

RESULTS

Participants correctly completed 73.4% of all scheduled assessments, demonstrating good compliance. Daily assessments took <2 minutes to complete. Participants reported high satisfaction with smartphone applications (6.3 of 7) and found them easy to use (6.2 of 7). Comparison of assessments obtained via telephone-based interview and EMA demonstrated high correlations (r = 0.81-0.97), supporting the validity of conducting these assessments via smartphone application in this population.

CONCLUSIONS

EMA conducted via smartphone demonstrates initial feasibility among adults with TBI and presents numerous opportunities for long-term monitoring of mood-related symptoms in real-world settings.

Exploratory associations with tumor necrosis factor-α, disinhibition and suicidal endorsement after traumatic brain injury

PURPOSE

To examine the relationship of Tumor Necrosis Factor (TNF)-α to disinhibition and suicidal endorsement after traumatic brain injury (TBI).

PARTICIPANTS

Adults with moderate to severe TBI (acute serum levels: n=48, n=543 samples; acute CSF levels: n=37, n=389 samples; chronic serum levels: n=48, n=326 samples).

MAIN MEASURES

TNFα levels (CSF, Serum) from time of injury to 12 months post-injury; Frontal Systems Behavior Scale - Disinhibition Subscale at 6 and 12 months post-injury; Patient Health Questionnaire at 6 and 12 months post-injury.

RESULTS

Participants with TBI had significantly higher CSF and serum TNFα levels than healthy controls (p<0.05). Acute and chronic serum TNFα was significantly associated with disinhibition at 6 months post-injury (p=0.009, p=0.029 respectively), and 6 month disinhibition was associated with suicidal endorsement at both 6 and 12 months (p=0.045, p=0.033 respectively) and disinhibition at 12 months post-injury (p<0.001).

CONCLUSION

These preliminary data suggest a biological to behavioral pathway of suicidality after TBI, from TNFα to disinhibition to suicidal endorsement. Future investigation is warranted to validate these findings and clarify what biological mechanisms might underlie these relationships.

A Rehabilomics framework for personalized and translational rehabilitation research and care for individuals with disabilities: Perspectives and considerations for spinal cord injury

Despite many people having similar clinical presentation, demographic factors, and clinical care, outcome can differ for those sustaining significant injury such as spinal cord injury (SCI) and traumatic brain injury (TBI). In addition to traditional demographic, social, and clinical factors, variability also may be attributable to innate (including genetic, transcriptomic proteomic, epigenetic) biological variation that individuals bring to recovery and their unique response to their care and environment. Technologies collectively called "-omics" enable simultaneous measurement of an enormous number of biomolecules that can capture many potential biological contributors to heterogeneity of injury/disease course and outcome. Due to the nature of injury and complex disease, and its associations with impairment, disability, and recovery, rehabilitation does not lend itself to a singular "protocolized" plan of therapy. Yet, by nature and by necessity, rehabilitation medicine operates as a functional model of "Personalized Care". Thus, the challenge for successful programs of translational rehabilitation care and research is to identify viable approaches to examine broad populations, with varied impairments and functional limitations, and to identify effective treatment responses that incorporate personalized protocols to optimize functional recovery. The Rehabilomics framework is a translational model that provides an "-omics" overlay to the scientific study of rehabilitation processes and multidimensional outcomes. Rehabilomics research provides novel opportunities to evaluate the neurobiology of complex injury or chronic disease and can be used to examine methods and treatments for person-centered care among populations with disabilities. Exemplars for application in SCI and other neurorehabilitation populations are discussed.

Variation in the BDNF gene interacts with age to predict mortality in a prospective, longitudinal cohort with severe TBI

BACKGROUND

Mortality predictions following traumatic brain injury (TBI), and our understanding of TBI pathology, may be improved by including genetic risk in addition to traditional prognostic variables. One promising target is the gene coding for brain-derived neurotrophic factor (BDNF), a ubiquitous neurotrophin important for neuronal survival and neurogenesis.

OBJECTIVE

We hypothesized the addition of BDNF genetic variation would improve mortality prediction models and that BDNF Met-carriers (rs6265) and C-carriers (rs7124442) would have the highest mortality rates post-TBI.

METHODS

This study examined BDNF functional single nucleotide polymorphisms rs6265 (val66met) and rs7124442 (T>C) in relation to mortality in a prospective, longitudinal cohort with severe TBI. We examined 315 individuals receiving care for a closed head injury within the University of Pittsburgh Medical Center, aged 16 to 74 years. Mortality was examined acutely (0-7 days postinjury) and postacutely (8-365 days postinjury). A gene risk score (GRS) was developed to examine both BDNF loci. Cox proportional hazards models were used to calculate hazard ratios for survivability post-TBI while controlling for covariates.

RESULTS

BDNF GRS was significantly associated with acute mortality, regardless of age. Interestingly, subjects in the hypothesized no-risk allele group had the lowest survival probability. Postacutely, BDNF-GRS interacted with age such that younger participants in the no-risk group had the highest survival probability, while older participants in the hypothesized no-risk group had the lowest probability of survival.

CONCLUSIONS

These data suggest complex relationships between BDNF and TBI mortality that interact with age to influence survival predictions beyond clinical variables alone. Evidence supporting dynamic, temporal balances of pro-survival/pro-apoptotic target receptors may explain injury and age-related gene associations.

Post-Traumatic Brain Injury: Genetic Susceptibility to Outcome

It is estimated that 2% of the population from industrialized countries live with lifelong disabilities resulting from traumatic brain injury (TBI) and roughly one in four adults are unable to return to work 1 year after injury because of physical or mental disabilities. TBI is a significant public health issue that causes substantial physical and economical repercussions for the individual and society. Electronic databases (PubMed, Web of Science, Google Scholar) were searched with the keywords traumatic brain injury, TBI, genes and TBI, TBI outcome, head injury. Human studies on non-penetrating traumatic brain injuries reported in English were included. To provide health care workers with the basic information for clinical management we summarize and compare the data on post-TBI outcome with regard to the impact of genetic variation: apolipoprotein E (APOE), brain-derived neurotrophic factor (BDNF), calcium channel, voltage dependent P/Q type, catechol-O-methyltransferase (COMT), dopamine receptor D2 and ankyrin repeat and kinase domain containing 1 (DRD2 and ANKK1), interleukin-1 (IL-1), interleukin-6 (IL-6), kidney and brain expressed protein (KIBRA), neurofilament, heavy polypeptide (NEFH), endothelial nitric oxide synthase 3 (NOS3), poly (ADP-ribose) polymerase-1 (PARP-1), protein phosphatase 3, catalytic subunit, gamma isozyme (PPP3CC), the serotonin transporter (5-HTT) gene solute carrier family 6 member (SLC6A4) and tumor protein 53 (TP53). It is evident that contradicting results are attributable to the heterogeneity of studies, thus further researches are warranted to effectively assess a relation between genetic traits and clinical outcome following traumatic injuries.