Speed of information processing in traumatic brain injury: modality-specific factors

Bypassing Striatal Learning Mechanisms Using Delayed Feedback to Circumvent Learning Deficits in Traumatic Brain Injury

OBJECTIVE

Feedback facilitates learning by guiding and modifying behaviors through an action-outcome contingency. As the majority of existing studies have focused on the immediate presentation of feedback, the impact of delayed feedback on learning is understudied. Prior work demonstrated that learning from immediate and delayed feedback employed distinct brain regions in healthy individuals, and compared to healthy individuals, individuals with traumatic brain injury (TBI) are impaired in learning from immediate feedback. The goal of the current investigation was to assess the effects of delayed vs immediate feedback on learning in individuals with TBI and examine brain networks associated with delayed and immediate feedback processing.

SETTING

Nonprofit research organization.

PARTICIPANTS

Twenty-eight individuals with moderate-to-severe TBI.

DESIGN

Participants completed a paired-associate word learning task while undergoing magnetic resonance imaging. During the task, feedback was presented either immediately, after a delay, or not at all (control condition).

MAIN MEASURES

Learning performance accuracy, confidence ratings, post-task questionnaire, and blood oxygen level-dependent signal.

RESULTS

Behavioral data showed that delayed feedback resulted in better learning performance than immediate feedback and no feedback. In addition, participants reported higher confidence in their performance during delayed feedback trials. During delayed vs immediate feedback processing, greater activation was observed in the superior parietal and angular gyrus. Activation in these areas has been previously associated with successful retrieval and greater memory confidence.

CONCLUSION

The observed results might be explained by delayed feedback processing circumventing the striatal dopaminergic regions responsible for learning from immediate feedback that are impaired in TBI. In addition, delayed feedback evokes less of an affective reaction than immediate feedback, which likely benefited memory performance. Indeed, compared to delayed feedback, positive or negative immediate feedback was more likely to be rated as rewarding or punishing, respectively. The findings have significant implications for TBI rehabilitation and suggest that delaying feedback during rehabilitation might recruit brain regions that lead to better functional outcomes.

Decision-making abilities under risk and ambiguity in adults with traumatic brain injury: what do we know so far? A systematic review and meta-analysis

Traumatic brain injury (TBI) is a major health and socio-economic problem since it is one of the major sources of death and disability worldwide. TBI patients usually show high heterogeneity in their clinical features, including both cognitive and emotional/behavioral alterations. As it specifically concerns cognitive functioning, these patients usually show decision-making (DM) deficits. DM is commonly considered a complex and multistep process that is strictly linked to both hot and cold executive functioning and is pivotal for daily life functioning and patients' autonomy. However, the results are not always in agreement, with some studies that report huge alterations in the DM processes, while others do not. The present systematic review and meta-analysis aims to integrate past literature on this topic, providing a clear and handy picture both for researchers and clinicians. Thirteen studies addressing domain-general DM abilities were included from an initial N = 968 (from three databases). Results showed low heterogeneity between the studies (I2 = 7.90, Q (12) = 13.03, p = .37) supporting the fact that, overall, TBI patients showed lower performance in DM tasks as compared to healthy controls (k = 899, g = .48, 95% CI [0.33; 0.62]) both in tasks under ambiguity and under risk. The evidence that emerged from this meta-analysis denotes a clear deficit of DM abilities in TBI patients. However, DM tasks seemed to have good sensitivity but low specificity. A detailed description of patients' performances and the role of both bottom-up, hot executive functions and top-down control functions have been further discussed. Finally, future directions and practical implications for both researchers and clinicians have been put forward.

The Birthday Party Test (BPT): A new picture description test to support the assessment of simultanagnosia in patients with acquired brain injury

There is broad consensus on the utility of complex pictures in the assessment of simultanagnosia in patients with acquired brain injury (ABI). To overcome various shortcomings of current instruments, we have developed the Birthday Party Test (BPT); a picture description test that contains a neutral scene, a balanced representation of events, and provides clear instructions and a scoring-aid. We have applied the BPT in a large group of patients with ABI (n = 502) and in an age-matched healthy control group (n = 194). Our results show that performance on the BPT was associated with a range of descriptive, neuropsychological and clinical characteristics and that poor test performance appeared to be more common in patients with etiologies that have an increased risk of bilateral damage. Furthermore, we assume a high correspondence between test performance on the BPT and the assessor's clinical judgment of likely having simultanagnosia in preliminary analyses. This study shows the potential usefulness of the BPT to support diagnostic decision making in simultanagnosia. The BPT is made freely available to facilitate its broad application in the clinical assessment of patients with visual impairment and to enable a further evaluation of its utility and validity in future studies.

Lateral Fluid Percussion Injury Causes Sex-Specific Deficits in Anterograde but Not Retrograde Memory

Cognitive impairment is a common symptom after traumatic brain injury (TBI). Memory, in particular, is often disrupted during chronic post-injury recovery. To understand the sex-specific effects of brain injury on retrograde and anterograde memory, we examined paired associate learning (PAL), spatial learning and memory, and fear memory after lateral fluid percussion TBI. We hypothesized that male and female mice would display unique memory deficits after TBI. PAL task acquisition was initiated via touchscreen operant conditioning 22 weeks before sham injury or TBI. Post-injury PAL testing occurred 7 weeks post-injury. Barnes maze and fear conditioning were completed at 14- and 15-weeks post-injury, respectively. Contrary to our expectations, behavioral outcomes were not primarily influenced by TBI. Instead, sex-specific differences were observed in all tasks which exposed task-specific trends in male TBI mice. Male mice took longer to complete the PAL task, but this was not affected by TBI and did not compromise the ability to make a correct choice. Latency to reach the goal box decreased across testing days in Barnes maze, but male TBI mice lagged in improvement compared to all other groups. Use of two learning indices revealed that male TBI mice were deficient in transferring information from 1 day to the next. Finally, acquisition and contextual retention of fear memory were similar between all groups. Cued retention of the tone-shock pairing was influenced by both injury and sex. Male sham mice displayed the strongest cued retention of fear memory, evidenced by increased freezing behavior across the test trial. In contrast, male TBI mice displayed reduced freezing behavior with repetitive tone exposure. An inverse relationship in freezing behavior to tone exposure was detected between female sham and TBI mice, although the difference was not as striking. Together, these studies show that retrograde memory is intact after lateral TBI. However, male mice are more vulnerable to post-injury anterograde memory deficits. These behaviors were not associated with gross pathological change near the site injury or in subcortical brain regions associated with memory formation. Future studies that incorporate pre- and post-injury behavioral analysis will be integral in defining sex-specific memory impairment after TBI.

Two Ecological Tools for Testing Slowness of Information Processing in Italian Patients with Moderate-to-Severe Traumatic Brain Injury

Slowness of Information Processing (SIP) is frequently experienced after traumatic brain injury (TBI); however, the impact of SIP on everyday functioning may be underestimated by standard neuropsychological tests.

OBJECTIVE

we aimed to adapt two ecological instruments assessing SIP in Italian patients with moderate-to-severe TBI, as formerly proposed by Winkens and colleagues for persons with stroke, testing also its possible relation with other neuropsychological processes and functional outcomes.

METHOD

we performed an observational study on 37 patients with moderate-to-severe TBI and 35 demographically matched healthy controls, who underwent the Mental Slowness Observation Test (MSOT) and the Mental Slowness Questionnaire (MSQ), which had been adapted through a pilot study on independent sample of participants; extensive neuropsychological and functional evaluations were performed as well.

RESULTS

We found good clinical and psychometric properties of the Italian adaptation of the MSOT and MSQ; also, performance on MSOT significantly correlated with executive functions. Moreover, patients with TBI are significantly slower and less accurate than healthy controls on the MSOT, in particular in tasks with time limits. Even if the subjective feeling of SIP does not differ between patients and controls, we found a significant correlation between MSQ and MSOT. Finally, the performances on the MSOT correlated with measures of functional outcome and community integration.

CONCLUSIONS

the results support the use of the MSOT and the MSQ to measure SIP in an ecological fashion in patients with TBI, so that specific treatments for persons with acquired brain injury can be prescribed.

Visuospatial Attention Allocation as an Indicator of Cognitive Deficit in Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Traumatic Brain Injury (TBI) is defined by changes in brain function resulting from external forces acting on the brain and is typically characterized by a host of physiological and functional changes such as cognitive deficits including attention problems. In the present study, we focused on the effect of TBI on the ability to allocate attention in vision (i.e., the use of endogenous and exogenous visual cues) by systematically reviewing previous literature on the topic. We conducted quantitative synthesis of 16 selected studies of visual attention following TBI, calculating 80 effect size estimates. The combined effect size was large (g = 0.79, p < 0.0001) with medium heterogeneity (I² = 68.39%). Subgroup analyses revealed an increase in deficit with moderate-to-severe and severe TBI as compared to mild TBI [F_{(2, 76)} = 24.14, p < 0.0001]. Task type was another key source of variability and subgroup analyses indicated that higher order attention processes were severely affected by TBI [F_{(2, 77)} = 5.66, p = 0.0051). Meta-regression analyses revealed significant improvement in visual attention deficit with time [p(mild) = 0.031, p(moderate-to-severe) = 0.002, p(severe) < 0.0001]. Taken together, these results demonstrate that visual attention is affected by TBI and that regular assessment of visual attention, using a systematic attention allocation task, may provide a useful clinical measure of cognitive impairment and change after TBI.

CHA2DS2-VASc Stroke Risk Index and Executive Functioning in Older Adults

OBJECTIVE

CHA2DS2-VASc is a stroke risk classification system developed to improve the precision of stroke risk classification. The current study examined the validity of CHA2DS2-VASc in a sample of healthy older adults using executive function measures of processing speed, working memory, and cognitive flexibility that are sensitive to cerebrovascular risk factors.

METHODS

Participants included 51 community-dwelling, healthy older adults (ages 53-86) recruited from both the community and cardiology clinics. CHA2DS2-VASc was utilized as a measure of stroke risk. Measures of executive functioning and processing speed included the Paced Auditory Serial Addition Test (PASAT), Delis-Kaplan Executive Function System (DKEFS) Number-Letter Switching, and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Coding.

RESULTS

CHA2DS2-VASc scores significantly predicted scores on the PASAT, DKEFS Number-Letter Switching, and RBANS Coding, such that greater stroke risk was associated with poorer performances on tests of executive functioning and processing speed. These relationships were observed over and above the potential influence of educational attainment and symptoms of depression.

CONCLUSION

Significant relations between stroke risk classification and performance on several measures of executive functioning provide support for a wider and more generalized use of CHA2DS2-VASc with healthy older adults. These findings further highlight the importance of early identification and treatment of stroke risk factors associated with cognitive decline. Findings suggest that CHA2DS2-VASc is a practical and useful tool for patients and their providers in the early detection of stroke risk and development of individualized treatment plans.

Reaction time and cognitive-linguistic performance in adults with mild traumatic brain injury

Objective: The purpose of this study was to characterize cognitive-linguistic performance in adults with mild traumatic brain injury (mTBI) to advance assessment and treatment practices. We hypothesized that individuals with mTBI would demonstrate longer reaction times (RTs) and greater error rates when compared to an orthopedic injury (OI) group on a category-naming task. Method: Participants were age and education-matched adults with mTBI (n = 20; 12 females) and adults with OI (n = 21; 5 females) who were discharged to home after an Emergency Department visit. Our primary task was a category-naming task shown to be sensitive to language deficits after mTBI. The task was adapted and administered under speeded and unspeeded conditions. Results: There was a significant main effect of condition on RT (speeded faster than unspeeded) and accuracy (more errors in the speeded condition). There was a marginally significant effect of group on errors, with more errors in the mTBI group than the OI group. Naming RT and accuracy in both conditions were moderately correlated with injury variables and symptom burden. Conclusions: Our data showed a marginal effect of group on accuracy of performance. Correlations found between naming and neurobehavioural symptoms, including sleep quality, suggest that the latter should be considered in future research.

Mild Traumatic Brain Injury Affects Cognitive Processing and Modifies Oscillatory Brain Activity during Attentional Tasks

Despite the high prevalence of mild traumatic brain injury (mTBI), current diagnostic tools to objectively assess cognitive complaints after mTBI continue to be inadequate. Our aim was to identify neuronal correlates for cognitive difficulties in mTBI patients by evaluating the possible alterations in oscillatory brain activity during a behavioral task known to be sensitive to cognitive impairment after mTBI. We compared oscillatory brain activity during rest and cognitive tasks (Paced Auditory Serial Addition Test [PASAT] and a vigilance test [VT]) with magnetoencephalography between 25 mTBI patients and 20 healthy controls. Whereas VT induced no significant differences compared with resting state in either group, patients exhibited stronger attenuation of 8- to 14-Hz oscillatory activity during PASAT than healthy controls in the left parietotemporal cortex (p ≤ 0.05). Further, significant task-related modulation in the left superior frontal gyrus and right prefrontal cortex was detected only in patients. The ∼10-Hz (alpha) peak frequency declined in frontal, temporal, and parietal regions during PASAT compared with rest (p < 0.016) in patients, whereas in controls it remained the same or showed a tendency to increase. In patients, the ∼10-Hz peak amplitude was negatively correlated with behavioral performance in the Trail Making Test. The observed alterations in the cortical oscillatory activity during cognitive load may provide measurable neurophysiological correlates of cognitive difficulties in mTBI patients, even at the individual level.

Mild Traumatic Brain Injury Burden Moderates the Relationship Between Cognitive Functioning and Suicidality in Iraq/Afghanistan-Era Veterans

OBJECTIVES

Suicidal ideation (SI) is highly prevalent in Iraq/Afghanistan-era veterans with a history of mild traumatic brain injury (mTBI), and multiple mTBIs impart even greater risk for poorer neuropsychological functioning and suicidality. However, little is known about the cognitive mechanisms that may confer increased risk of suicidality in this population. Thus, we examined relationships between neuropsychological functioning and suicidality and specifically whether lifetime mTBI burden would moderate relationships between cognitive functioning and suicidal ideation.

METHODS

Iraq/Afghanistan-era Veterans with a history of mTBI seeking outpatient services (N = 282) completed a clinical neuropsychological assessment and psychiatric and postconcussive symptom questionnaires.

RESULTS

Individuals who endorsed SI reported more severe post-traumatic stress disorder (PTSD), depression, and postconcussive symptoms and exhibited significantly worse memory performance compared to those who denied SI. Furthermore, mTBI burden interacted with both attention/processing speed and memory, such that poorer performance in these domains was associated with greater likelihood of SI in individuals with a history of three or more mTBIs. The pattern of results remained consistent when controlling for PTSD, depression, and postconcussive symptoms.

CONCLUSIONS

Slowed processing speed and/or memory difficulties may make it challenging to access and use past experiences to solve current problems and imagine future outcomes, leading to increases in hopelessness and SI in veterans with three or more mTBIs. Results have the potential to better inform treatment decisions for veterans with history of multiple mTBIs. (JINS, 2019, 25, 79-89).

Traumatic brain injury and frontal lobe plasticity

Over 1.4 million people in the United States experience traumatic brain injury (TBI) each year and approximately 52,000 people die annually due to complications related to TBI. Traditionally, TBI has been viewed as a static injury with significant consequences for frontal lobe functioning that plateaus after some window of recovery, remaining relatively stable thereafter. However, over the past decade there has been growing consensus that the consequences of TBI are dynamic, with unique characteristics expressed at the individual level and over the life span. This chapter first discusses the pathophysiology of TBI in order to understand its dynamic process and then describes the behavioral changes that are the result of injury with focus on frontal lobe functions. It integrates a historical perspective on structural and functional brain-imaging approaches used to understand how TBI impacts the frontal lobes, as well as more recent approaches to examine large-scale network changes after TBI. The factors most useful for outcome prediction are surveyed, along with how the theoretical frameworks used to predict recovery have developed over time. In this chapter, the authors argue for the need to understand outcome after TBI as a dynamic process with individual trajectories, taking a network theory perspective to understand the consequences of disrupting frontal systems in TBI. Within this framework, understanding frontal lobe dysfunction within a larger coordinated neural network to study TBI may provide a novel perspective in outcome prediction and in developing individualized treatments.

High Oxygen Exchange to Music Indicates Auditory Distractibility in Acquired Brain Injury: An fNIRS Study with a Vector-Based Phase Analysis

Attention deficits due to auditory distractibility are pervasive among patients with acquired brain injury (ABI). It remains unclear, however, whether attention deficits following ABI specific to auditory modality are associated with altered haemodynamic responses. Here, we examined cerebral haemodynamic changes using functional near-infrared spectroscopy combined with a topological vector-based analysis method. A total of thirty-seven participants (22 healthy adults, 15 patients with ABI) performed a melodic contour identification task (CIT) that simulates auditory distractibility. Findings demonstrated that the melodic CIT was able to detect auditory distractibility in patients with ABI. The rate-corrected score showed that the ABI group performed significantly worse than the non-ABI group in both CIT1 (target contour identification against environmental sounds) and CIT2 (target contour identification against target-like distraction). Phase-associated response intensity during the CITs was greater in the ABI group than in the non-ABI group. Moreover, there existed a significant interaction effect in the left dorsolateral prefrontal cortex (DLPFC) during CIT1 and CIT2. These findings indicated that stronger hemodynamic responses involving oxygen exchange in the left DLPFC can serve as a biomarker for evaluating and monitoring auditory distractibility, which could potentially lead to the discovery of the underlying mechanism that causes auditory attention deficits in patients with ABI.

Experimental Traumatic Brain Injury Identifies Distinct Early and Late Phase Axonal Conduction Deficits of White Matter Pathophysiology, and Reveals Intervening Recovery

Traumatic brain injury (TBI) patients often exhibit slowed information processing speed that can underlie diverse symptoms. Processing speed depends on neural circuit function at synapses, in the soma, and along axons. Long axons in white matter (WM) tracts are particularly vulnerable to TBI. We hypothesized that disrupted axon–myelin interactions that slow or block action potential conduction in WM tracts may contribute to slowed processing speed after TBI. Concussive TBI in male/female mice was used to produce traumatic axonal injury in the corpus callosum (CC), similar to WM pathology in human TBI cases. Compound action potential velocity was slowed along myelinated axons at 3 d after TBI with partial recovery by 2 weeks, suggesting early demyelination followed by remyelination. Ultrastructurally, dispersed demyelinated axons and disorganized myelin attachment to axons at paranodes were apparent within CC regions exhibiting traumatic axonal injury. Action potential conduction is exquisitely sensitive to paranode abnormalities. Molecular identification of paranodes and nodes of Ranvier detected asymmetrical paranode pairs and abnormal heminodes after TBI. Fluorescent labeling of oligodendrocyte progenitors in NG2CreER;mTmG mice showed increased synthesis of new membranes extended along axons to paranodes, indicating remyelination after TBI. At later times after TBI, an overall loss of conducting axons was observed at 6 weeks followed by CC atrophy at 8 weeks. These studies identify a progression of both myelinated axon conduction deficits and axon–myelin pathology in the CC, implicating WM injury in impaired information processing at early and late phases after TBI. Furthermore, the intervening recovery reveals a potential therapeutic window.

SIGNIFICANCE STATEMENT Traumatic brain injury (TBI) is a major global health concern. Across the spectrum of TBI severities, impaired information processing can contribute to diverse functional deficits that underlie persistent symptoms. We used experimental TBI to exploit technical advantages in mice while modeling traumatic axonal injury in white matter tracts, which is a key pathological feature of human TBI. A combination of approaches revealed slowed and failed signal conduction along with damage to the structure and molecular composition of myelinated axons in the white matter after TBI. An early regenerative response was not sustained yet reveals a potential time window for intervention. These insights into white matter abnormalities underlying axon conduction deficits can inform strategies to improve treatment options for TBI patients.

Nih toolbox premorbid ability adjustments: Application in a traumatic brain injury sample

PURPOSE/OBJECTIVE

Metrics to estimate premorbid cognitive ability, such as word reading tests, are important for clinical determination of cognitive changes following brain injury. In the present study, reading adjusted scores for the National Institutes of Health Toolbox Cognition Battery (NIHTB-CB) fluid tests were developed and validated with a sample of individuals with traumatic brain injury (TBI), to evaluate the clinical utility of reading-adjusted scores. Research Method/Design: The development sample included 843 adult participants, ages 20-85, from the NIHTB-CB standardization sample. A sample of 158 participants with complicated mild or moderate TBI (n = 74) or severe TBI (n = 84) were administered the NIHTB-CB, and comprised the validation sample. Scores were derived for the five fluid tests using four adjustment models: age-only, demographic-only, age-and-reading, and demographic-and-reading referenced scores.

RESULTS

Estimated premorbid ability varies depending on the reference model. Scores from each of the four reference models differentiated the comparison and TBI samples at the group level. However, performance varied by premorbid ability.

CONCLUSIONS/IMPLICATIONS

Premorbid ability affects identification of cognitive difficulties after TBI. Reading referenced scores provide an individualized estimate of the effects of premorbid ability than demographic characteristics alone. Each model identified a similar number of individuals as having cognitive difficulties; however, the models differed on which individuals had cognitive difficulties. The models had higher disagreement rates in the clinical compared with the comparison sample, particularly for individuals with lower premorbid ability. Clinical use and caveats are discussed. (PsycINFO Database Record

Using the NIH Toolbox Cognition Battery (NIHTB-CB) in individuals with traumatic brain injury

PURPOSE/OBJECTIVE

The NIH Toolbox for the Assessment of Neurological Behavior and Function Cognition Battery (NIHTB-CB) is a common data element for use in individuals with traumatic brain injury (TBI). This study evaluates its sensitivity and specificity in distinguishing individuals with complicated mild, moderate, or severe TBI, and provides support for the construct validity of the NIHTB-CB in individuals with TBI.

RESEARCH METHOD

One hundred eighty-two individuals with TBI (n = 83 complicated mild/moderate; n = 99 severe) completed the NIHTB-CB and neuropsychological criterion measures. Complete data were obtained on 158 participants. A control sample of 158 individuals without known neurological impairment was extracted from the NIHTB-CB normative sample. Multivariate analyses of variance determined the sensitivity of the NIHTB-CB measures to TBI and injury severity (complicated mild/moderate TBI, severe TBI, and controls) on the demographically corrected NIHTB-CB composite scores and seven subtests. A descriptive analysis of the sensitivity of each subtest was conducted. Finally, correlations between NIHTB-CB measures and criterion tests assessed convergent and discriminant validity.

RESULTS

Multivariate analyses indicated that there was a main effect for group (complicated mild/moderate vs. severe vs. controls) for fluid scores in the NIHTB-CB as opposed to only marginally significant results for the verbal scores. Moderate to strong relationships were found between the NIHTB-CB measures and their corresponding neuropsychological measures (convergent validity), whereas much smaller correlations were found between measures of different cognitive domains (discriminant validity).

CONCLUSIONS

Findings provide evidence of construct validity and the clinical utility of the NIHTB-CB in individuals with TBI. (PsycINFO Database Record

L-Carnitine and extendin-4 improve outcomes following moderate brain contusion injury

There is a need for pharmaceutical agents that can reduce neuronal loss and improve functional deficits following traumatic brain injury (TBI). Previous research suggests that oxidative stress and mitochondrial dysfunction play a major role in neuronal damage after TBI. Therefore, this study aimed to investigate two drugs known to have antioxidant effects, L-carnitine and exendin-4, in rats with moderate contusive TBI. L-carnitine (1.5 mM in drinking water) or exendin-4 (15 µg/kg/day, ip) were given immediately after the injury for 2 weeks. Neurological function and brain histology were examined (24 h and 6 weeks post injury). The rats with TBI showed slight sensory, motor and memory functional deficits at 24 h, but recovered by 6 weeks. Both treatments improved sensory and motor functions at 24 h, while only exendin-4 improved memory. Both treatments reduced cortical contusion at 24 h and 6 weeks, however neither affected gliosis and inflammatory cell activation. Oxidative stress was alleviated and mitochondrial reactive oxygen species was reduced by both treatments, however only mitochondrial functional marker protein transporter translocase of outer membrane 20 was increased at 24 h post injury. In conclusion, L-carnitine and exendin-4 treatments immediately after TBI can improve neurological functional outcome and tissue integrity by reducing oxidative stress.

Cognition and return to work after mild/moderate traumatic brain injury: A systematic review

BACKGROUND

Approximately two percent of the United States population are traumatic brain injury (TBI) survivors. The unemployment rate among them is substantial. Cognitive skills are essential to perform any job.

OBJECTIVE

We analyzed the literature on cognitive rehabilitation (CR) related to mild/moderate TBI to learn the influence of cognition on return to work (RTW) post TBI.

METHODS

We conducted a systematic review of the studies on CR related to RTW post TBI that were published between 2000 and 2015.

RESULTS

We critically reviewed 30 studies that met the inclusion criteria. Ten studies highlighted cognition as a predictor variable, seven studies demonstrated support for cognitive testing in RTW assessments, and 13 studies showed the efficacy of CR in facilitating RTW post TBI.

CONCLUSION

Cognition plays a significant role in predicting and facilitating RTW in patients with TBI.

Long-term effects of mild traumatic brain injuries to oculomotor tracking performances and reaction times to simple environmental stimuli

Understanding the long-term effects of concussive events remains a challenge for the development of modern medical practices and the prevention of recurrent traumas. In this study, we utilized indices of oculomotor performance and the ability to react to simple environmental stimuli to assess the long-term motor effects of traumatic brain injury in its mildest form (mTBI). We performed analysis of eye movement accuracy, investigated the presence of abnormal eye movements, and quantified time to react to simple environmental stimuli on long-term mTBI survivors. Results indicated the presence of impairments to basic neural functions used to explore and respond to environmental demands long after the occurrence of mTBIs. Specifically, the result revealed the presence of abnormal saccadic eye movements while performing horizontal smooth pursuit, diminished accuracy of primary saccadic horizontal eye movement, and a widespread slower reaction to both visual and auditory stimuli. The methodology used in this study indicated to be potentially useful in aiding future investigations of neural circuitry impaired by mTBI and provide indices of recovery in future clinical trials testing mTBI-related clinical interventions.

The paced auditory serial addition test for working memory assessment: Psychometric properties

Background: The paced auditory serial addition test (PASAT) was primarily developed to assess the effects of traumatic brain injury on cognitive functioning. Working memory (WM) is one of the most important aspects of cognitive function, and WM impairment is one of the clinically remarkable signs of aphasia. To develop the Persian version of PASAT, an initial version was used in individuals with aphasia (IWA).

Methods: In this study, 25 individuals with aphasia (29-60 years) and 85 controls (18-60 years) were included. PASAT was presented in the form of recorded 61 single-digit numbers (1 to 9). The participants repeatedly added the 2 recent digits. The psychometric properties of PASAT including convergent validity (using the digit memory span tasks), divergent validity (using results in the control group and IWA group), and face validity were investigated. Test-retest reliability was considered as well.

Results: The relationship between the PASAT and digit memory span tests was moderate to strong in the control group (forward digit memory span test: r= 0.52, p< 0.0001; backward digit memory span test: r = 0.48, p< 0.0001). A strong relationship was found in IWA (forward digit memory span test: r= 0.72, p< 0.0001; backward digit memory span test: r= 0.53, p= 0.006). Also, strong testretest reliability (intraclass correlation= 0.95, p< 0.0001) was observed.

Conclusion: According to our results, the PASAT is a valid and reliable test to assess working memory, particularly in IWA. It could be used as a feasible tool for clinical and research applications.

Cognitive fatigue in individuals with traumatic brain injury is associated with caudate activation

We investigated differences in brain activation associated with cognitive fatigue between persons with traumatic brain injury (TBI) and healthy controls (HCs). Twenty-two participants with moderate-severe TBI and 20 HCs performed four blocks of a difficult working memory task and four blocks of a control task during fMRI imaging. Cognitive fatigue, assessed before and after each block, was used as a covariate to assess fatigue-related brain activation. The TBI group reported more fatigue than the HCs, though their performance was comparable. Regarding brain activation, the TBI group showed a Task X Fatigue interaction in the caudate tail resulting from a positive correlation between fatigue and brain activation for the difficult task and a negative relationship for the control task. The HC group showed the same Task X Fatigue interaction in the caudate head. Because we had prior hypotheses about the caudate, we performed a confirmatory analysis of a separate dataset in which the same subjects performed a processing speed task. A relationship between Fatigue and brain activation was evident in the caudate for this task as well. These results underscore the importance of the caudate nucleus in relation to cognitive fatigue.

Interpreting Patterns of Low Scores on the NIH Toolbox Cognition Battery

INTRODUCTION

The National Institutes of Health Toolbox for Assessment of Neurological and Behavioral Function Cognition Battery is comprised of seven cognitive tests, including two tests measuring crystallized cognitive ability (i.e., vocabulary and reading) and five tests measuring fluid cognitive functioning (i.e., working memory, memory, speed of processing, and executive functioning). This study presents comprehensive base rate tables for the frequency of low scores in adults and older adults from the normative sample.

METHODS

Participants were 843 adults, ages 20-85, from the NIH Toolbox standardization sample who completed all seven cognition tests. Rates of low scores were derived for standard age-adjusted and fully-demographically-adjusted scores at multiple cut-scores. Base rates were stratified by education, crystallized intellectual ability, and cognitive domain.

RESULTS

Using the five demographically-adjusted fluid cognitive test scores, 45.9% of adults obtained one or more scores at or below the 16th percentile, and 16.8% obtained one or more score at or below the 5th percentile, which is consistent with findings from other neurocognitive test batteries.

DISCUSSION

Based on the study findings, nearly 50% of adults in the general population would meet psychometric criteria for a diagnosis of the Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) Mild Neurocognitive Disorder (MND). We developed new psychometric criteria for identifying MND using the NIH Toolbox Cognition Battery that reduce the false positive rate. Knowing these multivariate normative base rates will help researchers and clinicians interpret NIH Toolbox scores in people with neurodevelopmental, psychiatric, medical, neurological, and neurodegenerative disorders that affect cognitive functioning.

Cascade of Traumatic Brain Injury: A Correlational Study of Cognition, Postconcussion Symptoms, and Quality of Life

INTRODUCTION

Traumatic brain injury (TBI) constitutes a significant burden on health care resources in India. TBI is a dynamic process which involves damage to the brain thus leading to behavior cognitive and emotional consequences.

AIM

To study the cognitive profile, post-concussion symptoms (PCS), quality of life (QOL), and their correlation.

METHODS

A total of 60 patients with TBI were recruited and assessed for neuropsychological profile, PCS, and QOL, the correlation among the variables were analyzed.

RESULTS

The results suggest that TBI has series of consequences which is interrelated, and the study has implications for rehabilitation of TBI.

CONCLUSION

The study highlights the deficits of cognition, and its correlation with PCS and QOL, emphasizing integrated rehabilitation approach for patients with TBI.

Characterizing common workplace communication skills for disorders associated with traumatic brain injury: A qualitative study

BACKGROUND

Interpersonal skill deficits are the primary reason for workplace separation after traumatic brain injury (TBI). Communication is integral to interpersonal skills, but workplace communication demands are inadequately described in the rehabilitation literature.

OBJECTIVE

This study describes inter-stakeholder examples of workplace communication behaviors for a level of employment to which people with TBI commonly attempt to return.

METHODS

Setting: Mid-level workplaces.Design: Semi-structured interviews were audio recorded, transcribed verbatim, then analyzed using thematic content analysis. Findings were linked to common communication deficits in persons with TBI.Participants: A volunteer sample of twenty healthy individuals employed in the mid-level workplaces, ten employees and ten supervisors.Main Outcome Measure(s): Taxonomy of communication skill deficits common in persons with TBI and associated with mid-level workplaces.

RESULTS

Interviews revealed seven communication-related skills associated with mid-level employment: 1) spoken language processing; 2) verbal memory; 3) reading and writing; 4) verbal reasoning; 5) expressive pragmatics; 6) multi-tasking; and 7) social cognition.

CONCLUSION

Workers and supervisors from an assortment of mid-level jobs with differing job contents all identified similarly common and important cross-occupational communication-related skills. Findings provide a preliminary guide to assess and treat communication skills for patients who have work re-entry as a goal.

The influence of cognitive dysfunction on benefit from learning and memory rehabilitation in MS: A sub-analysis of the MEMREHAB trial

BACKGROUND

This study examined the influence of processing speed (PS) on benefit from treatment with the modified Story Memory Technique(©) (mSMT), a behavioral intervention shown to improve new learning and memory in multiple sclerosis (MS).

METHODS

This double-blind, placebo-controlled, randomized clinical trial included 85 participants with clinically definite MS, 45 assigned to the treatment group and 40 to the placebo-control group. Participants completed baseline and follow-up neuropsychological assessment. The present study represents a post-hoc analysis to examine the role of PS on treatment efficacy.

FINDINGS

The treatment group showed a significantly improved CVLT learning slope relative to the placebo group post-treatment, after co-varying PS performance. SDMT performance was a significant predictor of benefit from mSMT treatment, beyond group assignment. Post-hoc analysis indicated a significant correlation between the SDMT and overall cognition, indicating that the SDMT may be serving as a proxy for overall cognitive impairment.

INTERPRETATION

Performance on measures of cognitive dysfunction aside from learning and memory impact the benefit of mSMT treatment. While the current study focused on PS as a critical factor, PS may be serving as a marker for generalized cognitive dysfunction. Implications for cognitive rehabilitation in MS are discussed.

Induced mild systemic inflammation is associated with impaired ability to improve cognitive task performance by practice

Elevated inflammatory levels are linked to poorer cognition, but experimental confirmation is lacking. This report examined associations between cognitive performance and inflammation induced by exercise and vaccination. Thirty-six (exercise N = 18, vaccination N = 18) healthy males completed a paced auditory serial addition test (PASAT), which is a multifaceted measure of cognitive function. The task was completed in placebo and elevated inflammation states. Improvements in PASAT performance were related to inflammation. In the exercise study, IL-6 during the first PASAT negatively correlated with PASAT improvement (p = .022). In the vaccination study, increases in C-reactive protein between PASATs correlated with reduced PASAT improvement (p < .001). Inflammation was linked to reduced improvements in cognitive performance. Further research should identify the specific cognitive functions affects and the underlying mechanisms.

The rich get richer: brain injury elicits hyperconnectivity in core subnetworks

There remains much unknown about how large-scale neural networks accommodate neurological disruption, such as moderate and severe traumatic brain injury (TBI). A primary goal in this study was to examine the alterations in network topology occurring during the first year of recovery following TBI. To do so we examined 21 individuals with moderate and severe TBI at 3 and 6 months after resolution of posttraumatic amnesia and 15 age- and education-matched healthy adults using functional MRI and graph theoretical analyses. There were two central hypotheses in this study: 1) physical disruption results in increased functional connectivity, or hyperconnectivity, and 2) hyperconnectivity occurs in regions typically observed to be the most highly connected cortical hubs, or the "rich club". The current findings generally support the hyperconnectivity hypothesis showing that during the first year of recovery after TBI, neural networks show increased connectivity, and this change is disproportionately represented in brain regions belonging to the brain's core subnetworks. The selective increases in connectivity observed here are consistent with the preferential attachment model underlying scale-free network development. This study is the largest of its kind and provides the unique opportunity to examine how neural systems adapt to significant neurological disruption during the first year after injury.

NIH Toolbox Cognitive Battery (NIHTB-CB): the NIHTB Pattern Comparison Processing Speed Test

The NIH Toolbox (NIHTB) Pattern Comparison Processing Speed Test was developed to assess processing speed within the NIHTB for the Assessment of Neurological Behavior and Function Cognition Battery (NIHTB-CB). This study highlights validation data collected in adults ages 18-85 on this measure and reports descriptive data, test-retest reliability, construct validity, and preliminary work creating a composite index of processing speed. Results indicated good test-retest reliability. There was also evidence for both convergent and discriminant validity; the Pattern Comparison Processing Speed Test demonstrated moderate significant correlations with other processing speed tests (i.e., WAIS-IV Coding, Symbol Search and Processing Speed Index), small significant correlations with measures of working memory (i.e., WAIS-IV Letter-Number Sequencing and PASAT), and non-significant correlations with a test of vocabulary comprehension (i.e., PPVT-IV). Finally, analyses comparing and combining scores on the NIHTB Pattern Comparison Processing Speed Test with other measures of simple reaction time from the NIHTB-CB indicated that a Processing Speed Composite score performed better than any test examined in isolation. The NIHTB Pattern Comparison Processing Speed Test exhibits several strengths: it is appropriate for use across the lifespan (ages, 3-85 years), it is short and easy to administer, and it has high construct validity.

Speed of perceptual grouping in acquired brain injury

Evidence exists that damage to white matter connections may contribute to reduced speed of information processing in traumatic brain injury and stroke. Damage to such axonal projections suggests a particular vulnerability to functions requiring integration across cortical sites. To test this prediction, measurements were made of perceptual grouping, which requires integration of stimulus components. A group of traumatic brain injury and cerebral vascular accident patients and a group of age-matched healthy control subjects viewed arrays of dots and indicated the pattern into which stimuli were perceptually grouped. Psychophysical measurements were made of perceptual grouping as well as processing speed. The patient group showed elevated grouping thresholds as well as extended processing time. In addition, most patients showed progressive slowing of processing speed across levels of difficulty, suggesting reduced resources to accommodate increased demands on grouping. These results support the prediction that brain injury results in a particular vulnerability to functions requiring integration of information across the cortex, which may result from dysfunction of long-range axonal connection.

The role of processing speed in the Brief Visuospatial Memory Test - revised

The Brief Visuospatial Memory Test - Revised (BVMT-R) is a commonly used, commercialized, assessment tool to measure visuospatial learning and memory abilities across research and clinical settings. In this study we evaluated the influence of processing speed and executive functioning on BVMT-R learning, memory, and percent retention scores. A total of 141 cognitively healthy older adults completed the BVMT-R along with measures of visuoconstructional abilities (BVMT-R copy), speeded processing (Symbol Digit Modalities Test-oral), and executive function (FAS). After controlling for age and visuoconstructional abilities, hierarchical regression models showed that the processing speed measure was a unique predictor of both BVMT-R learning and memory performances, while the executive function measure was not. The visuoconstructional measure was the only unique predictor of BVMT-R percent retention. The findings suggest that, when interpreting the BVMT-R learning and memory scores of patients who exhibit speeded processing deficits, the impact of slowed processing speed on performance should be considered.

Prevalence of dual sensory impairment and its association with traumatic brain injury and blast exposure in OEF/OIF veterans

OBJECTIVE

To describe the prevalence of self-reported rates of auditory, visual, and dual sensory impairment (DSI) in Afghanistan and Iraq war Veterans receiving traumatic brain injury (TBI) evaluations.

DESIGN

Retrospective medical chart review.

PARTICIPANTS

Thirty-six thousand nine hundred nineteen Veterans who received a TBI evaluation between October 2007 and June 2009. Final sample included 12,521 subjects judged to have deployment-related TBI and a comparison group of 9106 participants with no evidence of TBI.

MAIN OUTCOME MEASURE

Self-reported auditory and visual impairment.

RESULTS

Self-reported sensory impairment rates were: 34.6% for DSI, 31.3% for auditory impairment only, 9.9% for visual impairment only, and 24.2% for none/mild sensory impairment. Those with TBI and blast exposure had highest rate of DSI. Regression analyses showed that auditory impairment was the strongest predictor of visual impairment, and vice versa, suggesting these impairments may derive from a common source.

CONCLUSIONS

Veterans who self-report clinically significant hearing or vision difficulty during routine TBI evaluation should be evaluated systematically and comprehensively to determine the extent of sensory impairment. Identifying DSI could allow clinicians to collaborate and maximize rehabilitation.

Slowing down after a mild traumatic brain injury: a strategy to improve cognitive task performance?

Long-term persistent attention and memory difficulties following a mild traumatic brain injury (TBI) often go undetected on standard neuropsychological tests, despite complaints by mild TBI individuals. We conducted a visual Repetition Detection working memory task to digits, in which we manipulated task difficulty by increasing cognitive load, to identify subtle deficits long after a mild TBI. Twenty-six undergraduate students with a self-report of one mild TBI, which occurred at least 6 months prior, and 31 non-head-injured controls took part in the study. Participants were not informed until study completion that the study's purpose was to examine cognitive changes following a mild TBI, to reduce the influence of "diagnosis threat" on performance. Neuropsychological tasks did not differentiate the groups, though mild TBI participants reported higher state anxiety levels. On our working memory task, the mild TBI group took significantly longer to accurately detect repeated targets on our task, suggesting that slowed information processing is a long-term consequence of mild TBI. Accuracy was comparable in the low-load condition and, unexpectedly, mild TBI performance surpassed that of controls in the high-load condition. Temporal analysis of target identification suggested a strategy difference between groups: mild TBI participants made a significantly greater number of accurate responses following the target's offset, and significantly fewer erroneous distracter responses prior to target onset, compared with controls. Results suggest that long after a mild TBI, high-functioning young adults invoke a strategy of delaying their identification of targets in order to maintain, and facilitate, accuracy on cognitively demanding tasks.

Stroop effects in persons with traumatic brain injury: selective attention, speed of processing, or color-naming? A meta-analysis

The color word Stroop test is the most common tool used to assess selective attention in persons with traumatic brain injury (TBI). A larger Stroop effect for TBI patients, as compared to controls, is generally interpreted as reflecting a decrease in selective attention. Alternatively, it has been suggested that this increase in Stroop effects is influenced by group differences in generalized speed of processing (SOP). The current study describes an overview and meta-analysis of 10 studies, where persons with TBI (N = 324) were compared to matched controls (N = 501) on the Stroop task. The findings confirmed that Stroop interference was significantly larger for TBI groups (p = .008). However, these differences may be strongly biased by TBI-related slowdown in generalized SOP (r² = .81 in a Brinley analysis). We also found that TBI-related changes in sensory processing may affect group differences. Mainly, a TBI-related increase in the latency difference between reading and naming the font color of a color-neutral word (r² = .96) was linked to Stroop effects. Our results suggest that, in using Stroop, it seems prudent to control for both sensory factors and SOP to differentiate potential changes in selective attention from other changes following TBI.

Longitudinal changes in the corpus callosum following pediatric traumatic brain injury

BACKGROUND

Atrophy of the corpus callosum (CC) is a documented consequence of moderate-to-severe traumatic brain injury (TBI), which has been expressed as volume loss using quantitative magnetic resonance imaging (MRI). Other advanced imaging modalities such as diffusion tensor imaging (DTI) have also detected white matter microstructural alteration following TBI in the CC. The manner and degree to which macrostructural changes such as volume and microstructural changes develop over time following pediatric TBI, and their relation to a measure of processing speed is the focus of this longitudinal investigation. As such, DTI and volumetric changes in the CC in participants with TBI and a comparison group at approximately 3 and 18 months after injury as well as their relation to processing speed were determined.

METHODS

Forty-eight children and adolescents aged 7-17 years who sustained either complicated mild or moderate-to-severe TBI (n = 23) or orthopedic injury (OI; n = 25) were studied. The participants underwent brain MRI and were administered the Eriksen flanker task at both time points.

RESULTS

At 3 months after injury, there were significant group differences in DTI metrics in the total CC and its subregions (genu/anterior, body/central and splenium/posterior), with the TBI group demonstrating significantly lower fractional anisotropy (FA) and a higher apparent diffusion coefficient (ADC) in comparison to the OI group. These group differences were also present at 18 months after injury in all CC subregions, with lower FA and a higher ADC in the TBI group. In terms of longitudinal changes in DTI, despite the group difference in mean FA, both groups generally demonstrated a modest increase in FA over time though this increase was only significant in the splenium/posterior subregion. Interestingly, the TBI group also generally demonstrated ADC increases from 3 to 18 months though the OI group demonstrated ADC decreases over time. Volumetrically, the group differences at 3 months were marginal for the midanterior and body/central subregions and total CC. However, by 18 months, the TBI group demonstrated a significantly decreased volume in all subregions except the splenium/posterior area relative to the OI group. Unlike the OI group, which showed a significant volume increase in subregions of the CC over time, the TBI group demonstrated a significant and consistent volume decrease. Performance on a measure of processing speed did not differentiate the groups at either visit, and only the OI group showed significantly improved performance over time. Processing speed was related to FA in the splenium/posterior and total CC only in the TBI group on both occasions, with a stronger relation at 18 months.

CONCLUSION

In response to TBI, macrostructural volume loss in the CC occurred over time; yet, at the microstructural level, DTI demonstrated both indicators of continued maturation and development even in the damaged CC, as well as evidence of potential degenerative change. Unlike volumetrics, which likely reflects the degree of overall neuronal loss and axonal damage, DTI may reflect some aspects of postinjury maturation and adaptation in white matter following TBI. Multimodality imaging studies may be important to further understand the long-term consequences of pediatric TBI.

Mental fatigue and impaired information processing after mild and moderate traumatic brain injury

PRIMARY OBJECTIVE

Mental fatigue is a common symptom after brain injury. Its mechanisms are not fully understood and it has been difficult to find an objective way of measuring it. The aim was to compare cognitive tests with a new self-assessment questionnaire about mental fatigue.

METHODS AND PROCEDURES

Individuals reporting mental fatigue for 6 months or more after mild traumatic brain injury (MTBI) or traumatic brain injury (TBI) and controls were assessed for subjective fatigue, information processing speed, working memory and attention. Depression and anxiety were also assessed in the individuals with brain injury.

RESULTS

Individuals with MTBI or TBI reported significantly more problems with mental fatigue and related symptoms than controls. A significantly decreased information processing speed (digit symbol-coding, reading speed, trail making test) was found in those on sick leave due to MTBI or TBI, compared to controls. Divided attention was affected to a lesser extent and no effect was detected on working memory.

CONCLUSION

Mental fatigue after MTBI can last for several years. It can be profoundly disabling and affect working capacity as well as social activities. Subjective mental fatigue following brain injury is suggested to mainly correlate with objectively measured information processing speed.

Distress tolerance and psychopathological symptoms and disorders: a review of the empirical literature among adults

We review theory and empirical study of distress tolerance, an emerging risk factor candidate for various forms of psychopathology. Despite the long-standing interest in and promise of work on distress tolerance for understanding adult psychopathology, there has not been a comprehensive review of the extant empirical literature focused on the construct. As a result, a comprehensive synthesis of theoretical and empirical scholarship on distress tolerance, including integration of extant research on the relations between distress tolerance and psychopathology, is lacking. Inspection of the scientific literature indicates that there are a number of promising ways to conceptualize and measure distress tolerance, as well as documented relations between distress tolerance factors and psychopathological symptoms and disorders. Although promising, there also is notable conceptual and operational heterogeneity across the distress tolerance literature. Moreover, a number of basic questions remain unanswered regarding the associations between distress tolerance and other risk and protective factors and processes, as well as its putative role(s) in vulnerability for and resilience to psychopathology. Thus, the current article provides a comprehensive review of past and contemporary theory and research and proposes key areas for future empirical study of this construct.

Attentional control and slowness of information processing after severe traumatic brain injury

Attention is a basic cognitive function and a prerequisite for other cognitive processes and is frequently impaired after traumatic brain injury. In the present study, 29 severe traumatic brain injury patients and 30 control subjects completed a battery of three neuropsychological tests of attention (WCST, TMT, Stroop). The aim was to clarify the attentional mechanisms underlying tests performance and to explore the types of attentional impairment after severe traumatic brain injury. Significant differences were found between the control and clinical groups in almost all measures. However, some of these differences disappeared when the speed of information processing was controlled using covariance analysis. In addition, a factor analysis revealed a four-factor solution explaining 89.6% of the variance in the data, i.e. cognitive flexibility, speed of processing, interference and working memory. This result supports the view of at least four different subprocesses of attentional control underlie test performance and allows one to differentiate between high- and low-level processes. The implications for neuropsychological assessment and rehabilitation are discussed.