Sustained attention in patients with mild traumatic brain injury

Brain functional connectivity in children with a mild traumatic brain injury: A scoping review

INTRODUCTION

The occurrence of mild traumatic brain injury(mTBI) is estimated at 0,2-0,3% cases annually. Following a mTBI, some children experience persistent symptoms, and functional connectivity(FC) changes may be implicated. However, characteristics of FC have not been widely described in this population. This scoping review aimed to identify and understand the impacts of mTBI on EEG-measured FC in children, provide an overview of the available literature, detail analysis techniques, and describe gaps in the research.

METHODS

PubMed, Web of Science, Medline, Embase, ProQuest and CINAHL were searched up to June 25, 2023, with the terms child, mTBI, EEG, FC, and their synonyms. Ten studies were identified.

RESULTS

Five studies reported significant differences between the mTBI group and controls. In addition to group differences, six studies reported significant variation over time. Brain Network Analysis(BNA), utilized in seven studies, was the primary FC analysis recorded. Two of the five studies that reported significant differences following mTBI utilized the BNA. The other three applied alternative analysis methods.

DISCUSSION

FC assessment based on EEG can identify some differences in children with mTBI. BNA was more useful in following changes over time. Further research is suggested, considering the limited age range and number of retrieved studies.

Traumatic Brain Injury, Abuse, and Poor Sustained Attention in Youth and Young Adults Who Previously Experienced Foster Care

Youth and young adults who previously experienced foster care are prone to negative life events, such as physical injuries, and adverse childhood experiences (ACE), such as abuse, neglect, and household dysfunction. The purpose of the present study was to identify the prevalence of traumatic brain injury (TBI), ACE, and poor sustained attention and the associations of these events in this group of vulnerable persons. Participants completed standardized questionnaires on the prevalence of self-reported TBI (TBI) and ACE and performed the Sustained Attention to Response Task (SART) test to measure sustained attention. Chi-squared and Kruskal-Wallis rank-sum tests were used to assess demographic differences and associations between TBI and ACE. Sustained attention was assessed using analysis of variance and linear modeling. Seventy-one participants-46 youth and young adults who previously experienced foster care (vulnerable group) and 25 age-matched healthy controls-completed the standardized questionnaires. Analyses indicated that vulnerable participants reported markedly higher rates of TBI and ACE than healthy controls. Vulnerable persons with TBI reported significantly higher Total ACE scores (p = 0.02), were more likely to have a history of family dysfunction (p = 0.02), and were more likely to have lived with a mentally ill guardian (p = 0.01) than vulnerable persons with no TBI. TBI was significantly associated with Total Errors (p = 0.001 and p = 0.02) and Omission Errors (p < 0.001 and p = 0.01) in all participants and in vulnerable participants, respectively, after adjusting for education level.

Assessing the Long-Term Impact of Concussion upon Cognition: A 5-Year Prospective Investigation

OBJECTIVE

Jockeys have high rates of concussion, with 5% of jockeys receiving at least one concussion annually. The impact of acute concussion upon cognition is well understood, but less is known about the long-term effects of concussion upon cognition. Our aim was to assess the impact of concussion upon jockeys who had provided pre-concussion assessments of cognition using a prospective design.

METHOD

In this study, over a 5-year period, we assessed the cognitive performance of jockeys with ≥1 medically diagnosed concussion (MDC; n = 17, months since concussion, M = 29.18), against those who had not been concussed (NC; n = 41). Jockeys who had not been concussed in the preceding 6 months completed four computer-based cognitive assessments from the CogSport battery.

RESULTS

Unlike the majority of the small existing literature, there was no difference (p ≥ .05) between the MDC and NC groups after controlling for age and baseline performance. Additionally, we used a measure of reliable change to assess for clinically meaningful decrements from baseline in each test and composite score 5 years later. None of the jockeys in the MDC group recorded significant decrements on any CogSport measure from baseline (z > -1.65).

CONCLUSIONS

The findings suggest that the presence of concussion does not result in persistent decrements in cognitive performance and that when findings are considered collectively, assessing factors beyond medically diagnosed concussion (e.g., chronic stress, undiagnosed concussion) may improve the interpretation of our current findings.

Longitudinal Trajectories of Sustained Attention Development in Children and Adolescents with ADHD

The present study characterizes changes in sustained attention ability over ages 9-14, and whether longitudinal trajectories of attention development differ between persistent ADHD, remitted ADHD and control groups. The Sustained Attention to Response Task (SART) was administered to 120 children with ADHD and 123 controls on three occasions between ages 9 and 14. Trajectories of sustained attention development, indicated by changes in SART performance (standard deviation of response time [SDRT], omission errors, and ex-Gaussian parameters sigma and tau), were examined using generalized additive mixed models. For all measures there was a significant main effect of age; response time variability and number of omission errors improved linearly as children aged. However, children with ADHD had significantly greater SDRT, tau and omission errors than controls across waves. There were no significant group differences in sigma, indicating that the greater overall response time variability (SDRT) observed in ADHD was likely driven by more intermittent long responses (larger tau). Trajectories of sustained attention performance did not differ between children with persistent ADHD or ADHD in remission. Longitudinal trajectories of sustained attention development are comparable between ADHD and controls, however children with ADHD (regardless of remission status) display a performance deficit equivalent to typical controls 1-3 years younger. Findings highlight the need for continued clinical support for children in remission from ADHD and provide support for tau as an endophenotype of ADHD.

Response inhibition in Veterans with a history of mild traumatic brain injury: The role of self-reported complaints in objective performance

INTRODUCTION

Although objective deficits in response inhibition (RI) have been detected in civilians with mild traumatic brain injury (mTBI), it remains unclear whether objective RI is worse in military Veterans with mTBI despite the prevalence of self-reported disinhibition. Assessing RI in Veterans is critical due to their unique characteristics, including combat and blast exposure, in addition to the prevalence of psychiatric comorbidity. Therefore, the aims of this study were to (1) examine RI performance in Veterans with mTBI compared to non-mTBI Veterans and (2) compare RI performance in well-defined subgroups of mTBI Veterans with and without self-reported complaints of disinhibition to non-mTBI Veterans.

METHOD

53 mTBI Veterans and 37 non-mTBI Veterans completed a Go/No-Go RI task and measures of self-reported disinhibition (Frontal Systems Behavior Scale) and psychiatric symptoms. ANCOVAs covarying for mood and demographics compared RI performances of the non-mTBI Veterans to (1) the total sample of mTBI Veterans (n= 53) and to (2) mTBI Veterans with elevated (t-score ≥ 60; mTBI-SubjDis; n= 23) and low (t-score < 60; mTBI-NoSubjDis; n= 30) levels of self-reported disinhibition.

RESULTS

There were no significant differences in RI between the mTBI group as a whole and the non-mTBI Veterans group. However, when Veterans with mTBI were divided into groups by clinically-significant concern about their disinhibition, the mTBI-SubjDis group demonstrated significantly worse RI than the mTBI-NoSubjDis and non-mTBI Veteran groups. No significant differences in RI performance were observed between the mTBI-NoSubjDis and non-mTBI Veteran groups.

CONCLUSIONS

Results indicate that mTBI Veterans with elevated levels of self-reported disinhibition show diminished performance on objective measures of RI, independent of mood. Findings highlight the unique contribution of subjective complaints on executive functioning in mTBI, and they underscore the importance of assessing cognitive complaints in order to identify those most at risk for poor-long term outcomes.

Neuroimaging and Psychometric Assessment of Mild Cognitive Impairment After Traumatic Brain Injury

Traumatic brain injury (TBI) can be serious partly due to the challenges of assessing and treating its neurocognitive and affective sequelae. The effects of a single TBI may persist for years and can limit patients’ activities due to somatic complaints (headaches, vertigo, sleep disturbances, nausea, light or sound sensitivity), affective sequelae (post-traumatic depressive symptoms, anxiety, irritability, emotional instability) and mild cognitive impairment (MCI, including social cognition disturbances, attention deficits, information processing speed decreases, memory degradation and executive dysfunction). Despite a growing amount of research, study comparison and knowledge synthesis in this field are problematic due to TBI heterogeneity and factors like injury mechanism, age at or time since injury. The relative lack of standardization in neuropsychological assessment strategies for quantifying sequelae adds to these challenges, and the proper administration of neuropsychological testing relative to the relationship between TBI, MCI and neuroimaging has not been reviewed satisfactorily. Social cognition impairments after TBI (e.g., disturbed emotion recognition, theory of mind impairment, altered self-awareness) and their neuroimaging correlates have not been explored thoroughly. This review consolidates recent findings on the cognitive and affective consequences of TBI in relation to neuropsychological testing strategies, to neurobiological and neuroimaging correlates, and to patient age at and assessment time after injury. All cognitive domains recognized by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) are reviewed, including social cognition, complex attention, learning and memory, executive function, language and perceptual-motor function. Affect and effort are additionally discussed owing to their relationships to cognition and to their potentially confounding effects. Our findings highlight non-negligible cognitive and affective impairments following TBI, their gravity often increasing with injury severity. Future research should study (A) language, executive and perceptual-motor function (whose evolution post-TBI remains under-explored), (B) the effects of age at and time since injury, and (C) cognitive impairment severity as a function of injury severity. Such efforts should aim to develop and standardize batteries for cognitive subdomains—rather than only domains—with high ecological validity. Additionally, they should utilize multivariate techniques like factor analysis and related methods to clarify which cognitive subdomains or components are indeed measured by standardized tests.

QEEG correlates of cognitive processing speed in children and adolescents with traumatic brain injuries

Both quantitative electroencephalography (qEEG) and cognitive measures have been used to understand the underlying brain changes that occur in individuals after experiencing a traumatic brain injury, however, research exploring the relationship between qEEG patterns and cognitive test performance is scarcely studied in school-aged populations. The purpose of the present study was to explore first, the neuropsychological and academic deficits in young individuals with TBI; and second, the underlying relationship between qEEG patterns and cognitive test performance. Analyses included 21 school-aged participants whom have experienced a recent TBI and 15 school-aged participants whom have never experienced a TBI. Mean subtest and composite scores were compared and regression analyses were used to determine whether alpha band and beta band qEEG coherence values predicted processing speed measures. Results suggest that young individuals who experienced a recent TBI exhibit general deficits in cognition and academic skills beyond what would be expected in the general population. Further, beta band coherence with the frontal brain regions significantly predicted processing speed scores, providing evidence of a relationship between qEEG patterns and processing speed. This outlines a relatively inexpensive method for utilizing neural connectivity to verify cognitive deficits for school-aged individuals with a recent TBI.

Trauma-related psychiatric and behavioral conditions are uniquely associated with sustained attention dysfunction

OBJECTIVE

It is increasingly recognized that trauma victims, particularly Veterans, have co-occurring psychological and physical conditions that impact cognition, especially the domains of sustained attention and executive functioning. Although previous work has generally attempted to isolate the unique cognitive effects of common combat-related comorbidities, less work has been done to examine how these conditions co-occur, and whether unique cognitive signatures accompany certain clinical combinations.

METHOD

To address this gap, we examined how several deployment-related conditions were associated with performance on a well-validated measure of sustained attention (i.e., gradual onset continuous performance task [gradCPT]) and a battery of standard neuropsychological measures in 123 Veterans from the Translational Research Center for TBI and Stress Disorders. Initially, a Principal component analysis was conducted to investigate how comorbid conditions grouped together.

RESULTS

Several sustained attention measures from the gradCPT were differentially associated with four unique combinations of trauma-related pathology. Specifically, a somatic component representing the combination of current pain, sleep disturbance, and mild traumatic brain injury was associated with a higher rate of failures of attentional engagement. On the other hand, a comorbid posttraumatic stress disorder (PTSD) and mood disorder component (moodPTSD), as well as a substance use disorder component, were associated with higher rates of inhibitory control failures. Increased attentional instability was associated with moodPTSD as well as an anxiety disorder component. In contrast, the cognitive effects of deployment-related trauma were not observed on standard neuropsychological measures.

CONCLUSION

These findings suggest that unique combinations of trauma-related pathology have dissociable effects on sustained attentional control. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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.

Cognitive Contributors to Multiple Errands Test (MET) Performance

OBJECTIVE

The Multiple Errands Test (MET) was designed to measure the effect of executive dysfunction on everyday life activities, but little is known about the cognitive requirements for successful performance. This study's objective was to investigate cognitive functions associated with successful MET performance, specifically, the Baycrest-MET.

METHOD

Correlation analysis examined relationships between Baycrest-MET performance and neuropsychological functioning in participants with acquired brain injury (ABI; N = 27).

RESULTS

The association of tasks omitted with executive function (EF) accounted for 15.2%-42.3% of the variance; the association of tasks omitted with attention and processing speed, for 16.8%-24.0%; and the association of tasks omitted and total rule breaks with visuospatial memory, for 18.5%-31.4%.

CONCLUSION

Poor performance on the Baycrest-MET in people with ABI is associated with impairments of EF, attention, memory, and processing speed. Different patterns of performance may arise from different constellations of impairments.

Neuropsychology of traumatic brain injury: An expert overview

Traumatic brain injury (TBI) is a serious healthcare problem, and this report is a selective review of recent findings on the epidemiology, pathophysiology and neuropsychological impairments following TBI. Patients who survive moderate-to-severe TBI frequently suffer from a wide range of cognitive deficits and behavioral changes due to diffuse axonal injury. These deficits include slowed information-processing and impaired long-term memory, attention, working memory, executive function, social cognition and self-awareness. Mental fatigue is frequently also associated and can exacerbate the consequences of neuropsychological deficits. Personality and behavioral changes can include combinations of impulsivity and apathy. Even mild TBI raises specific problems: while most patients recover within a few weeks or months, a minority of patients may suffer from long-lasting symptoms (post-concussion syndrome). The pathophysiology of such persistent problems remains a subject of debate, but seems to be due to both injury-related and non-injury-related factors.

Neuropsychological Profile of Lifetime Traumatic Brain Injury in Older Veterans

OBJECTIVES

The aim of this study was to characterize the neuropsychological profile of lifetime traumatic brain injury (TBI) in older Veterans.

METHODS

Participants were 169 older Veterans [mean age=79.1 years (range, 51-97 years), 89% male, 92% Caucasian], 88 with lifetime TBI and 81 without TBI, living in Veterans' retirement homes in independent residence. TBI history was ascertained with the Ohio State TBI Identification Method structured interview. Cognition was assessed with neuropsychological tests: Raw scores were converted to Z-scores compared to age-corrected normative data and combined into five domain composite Z-scores (attention/working memory, learning/memory, language, processing speed, executive functioning). We investigated the association between TBI and performance in each cognitive domain in linear mixed effects models, with and without adjustment for demographics, medical comorbidities, and psychiatric variables.

RESULTS

Compared to those without TBI, older Veterans with TBI had greater deficits in processing speed (estimate=-.52; p=.01; f 2=.08 in fully adjusted model) and executive functioning (estimate=-.41; p=.02; f 2=.06 in fully adjusted model) but performed similarly in the attention/working memory, learning/memory, and language domains (all p>.05). TBI-associated deficits were most prominent among individuals with multiple mild TBIs and those with any moderate-to-severe TBI, but were not clearly present among those with single mild TBI.

CONCLUSIONS

The neuropsychological profile of lifetime TBI in older Veterans is characterized by slowed processing speed and executive dysfunction, especially among those with greater injury burden. This pattern may reflect long-standing deficits or a TBI-associated cognitive decline process distinct from Alzheimer's disease. (JINS, 2017, 23, 56-64).

Tonic and phasic alertness training: a novel treatment for executive control dysfunction following mild traumatic brain injury

Many individuals with traumatic brain injury (TBI) suffer difficulty regulating fundamental aspects of attention (focus, sustained attention) and may also exhibit hypo- or hyper-states of alertness. Deficits in the state of attention may underlie or exacerbate higher order executive dysfunction. Recent studies indicate that computerized cognitive training targeting attentional control and alertness can ameliorate attention deficits evident in patients with TBI or acquired brain injury. The current study examined whether improvements in attentional state following training can also influence performance on higher-order executive function and mood in individuals with mild TBI (mTBI). The current study examined five patients with executive control deficits as a result of mTBI, with or without persistent anxiety. Three patients engaged in ~5 hours of an executive control training task targeting inhibitory control and sustained attention; two additional patients were re-tested following the same period of time. Performance on standard neuropsychological measures of attention, executive function, and mood were evaluated pre- and post-training. The results indicate that tonic and phasic alertness training may improve higher-order executive function and mood regulation in individuals with TBI.

Physiological emotional under-arousal in individuals with mild head injury

PRIMARY OBJECTIVES

This study examined the potential emotional sequelae following self-reported mild head injury (MHI; e.g. 'altered state of consciousness' [ASC]) in university students with a particular focus on arousal status and responsivity to experimental manipulation of arousal.

RESEARCH DESIGN

A quasi-experimental design (n = 91) was used to examine arousal status (self-reported and physiological indices) and response to manipulated arousal (i.e. induced psychosocial stress/activation; reduced activation/relaxation) between persons who acknowledged prior MHI and persons with no-MHI.

MAIN OUTCOME AND RESULTS

University students who self-reported MHI were physiologically under-aroused and less responsive to stressors (both laboratory and environmental) compared to their no-MHI cohort. Those with reported loss of consciousness demonstrated the most attenuated emotional arousal responses (i.e. flattened electrodermal responsivity) relative to those with only a reported ASC, followed by those with no-MHI.

CONCLUSIONS

The under-arousal in traumatic brain injury has been hypothesized to be associated with ventromedial prefrontal cortex disruption. This under-arousal may be mirrored in persons who self-report experiencing subtle head trauma. Students who reported MHI may be less able to physiologically respond and/or cognitively appraise stressful experiences as compared to their no-MHI cohort; and experience subtle persistent consequences despite the subtle nature of the reported head trauma.

Long-term effects of mild traumatic brain injury on cognitive performance

Although a proportion of individuals report chronic cognitive difficulties after mild traumatic brain injury (mTBI), results from behavioral testing have been inconsistent. In fact, the variability inherent to the mTBI population may be masking subtle cognitive deficits. We hypothesized that this variability could be reduced by accounting for post-concussion syndrome (PCS) in the sample. Thirty-six participants with mTBI (>1 year post-injury) and 36 non-head injured controls performed information processing speed (Paced Visual Serial Addition Task, PVSAT) and working memory (n-Back) tasks. Both groups were split by PCS diagnosis (4 groups, all n = 18), with categorization of controls based on symptom report. Participants with mTBI and persistent PCS had significantly greater error rates on both the n-Back and PVSAT, at every difficulty level except 0-Back (used as a test of performance validity). There was no difference between any of the other groups. Therefore, a cognitive deficit can be observed in mTBI participants, even 1 year after injury. Correlations between cognitive performance and symptoms were only observed for mTBI participants, with worse performance correlating with lower sleep quality, in addition to a medium effect size association (falling short of statistical significance) with higher PCS symptoms, post-traumatic stress disorder (PTSD), and anxiety. These results suggest that the reduction in cognitive performance is not due to greater symptom report itself, but is associated to some extent with the initial injury. Furthermore, the results validate the utility of our participant grouping, and demonstrate its potential to reduce the variability observed in previous studies.

The Association between Pain-Related Variables, Emotional Factors, and Attentional Functioning following Mild Traumatic Brain Injury

This study examined how MTBI concomitants such as pain variables, depression, and anxiety were related to attentional functioning at different stages of recovery. Participants having sustained a MTBI who were in the earlier phase of recovery showed, compared to controls, slower reaction times and larger intra-individual variability on a Computerized Pictorial Stroop Task (CPST). They also reported more post-concussion symptoms, pain intensity and disability, whereas MTBI participants who were in the later phase of recovery presented a higher rate of post-concussive symptoms and somewhat higher pain intensity/disability. MTBI participants' scores on the cognitive items of the post-concussion symptoms scale were positively correlated with reaction times on the CPST, while pain intensity/disability levels were negatively correlated with standard attention measures. Results indicate that obtaining response times and intra-individual variability measures using tests such as the CPST represents an effective means for measuring recovery of attentional function, and that pain intensity/disability should be systematically assessed after a MTBI.

Component analysis of verbal fluency in patients with mild traumatic brain injury

We set out to examine the sensitivity of switching and clustering component scores of verbal fluency in patients with mild traumatic brain injury (mTBI). Clustering and switching scores were compared between patients with mTBI and healthy normal controls as well as those with moderate TBI and severe TBI. Fifty-four healthy controls along with 20 mild TBI, 8 moderate TBI, and 12 severe TBI patients were included in the study. Our findings demonstrate that component score effect sizes were larger than those of total words generated for both phonemic and semantic fluency. This pattern of finding held true regardless of comparison group. In addition, semantic fluency component scores were found to correspond to larger component score effect sizes than did phonemic fluency component scores. Our findings demonstrate that component scores derived from the Controlled Oral Word Association Test may be sufficient to reliably capture the effects of unremitting injury (i.e., more than 3 months post status) to the frontal and temporal brain as evinced in cases of unremitting mTBI. This differential pattern of performance provides preliminary evidence for the potential usefulness of switching and clustering in the assessment of mTBI. Given the small sample sizes employed in our study, however, future studies are needed to determine whether component measures of verbal fluency have discriminative ability.

Towards systemic sustainable performance of TBI care systems: emergency leadership frontiers

Background

Traumatic brain injuries (TBIs) continue as a twenty-first century subterranean and almost invisible scourge internationally. TBI care systems provide a safety net for survival, recovery, and reintegration into social communities from this scourge, particularly in Canada, the European Union, and the USA.

Aims

This paper examines the underlying issues of systemic performance and sustainability of TBI care systems, in the light of decreasing care resources and increasing demands for services.

Methods

This paper reviews the extant literature on TBI care systems, systems reengineering, and emergency leadership literature.

Results

This paper presents a seven care layer paradigm, which forms the essence of systemic performance in the care of patients with TBIs. It also identifies five key strategic drivers that hold promise for the future systemic sustainability of TBI care systems.

Conclusions

Transformational leadership and engagement from the international emergency medical community is the key to generating positive change. The sustainability/performance care framework is relevant and pertinent for consideration internationally and in the context of other emergency medical populations.

Diffusion tensor imaging and white matter lesions at the subacute stage in mild traumatic brain injury with persistent neurobehavioral impairment

Mild traumatic brain injury (mTBI) can induce long-term behavioral and cognitive disorders. Although the exact origin of these mTBI-related disorders is not known, they may be the consequence of diffuse axonal injury (DAI). Here, we investigated whether MRI at the subacute stage can detect lesions that are associated with poor functional outcome in mTBI by using anatomical images (T(1) ) and diffusion tensor imaging (DTI). Twenty-three patients with mTBI were investigated and compared with 23 healthy volunteers. All patients underwent an MRI investigation and clinical tests between 7 and 28 days (D15) and between 3 and 4 months (M3) after injury. Patients were divided in two groups of poor outcome (PO) and good outcome (GO), based on their complaints at M3. Groupwise differences in gray matter partial volume between PO patients, GO patients and controls were analyzed using Voxel-Based Morphometry (VBM) from T(1) data at D15. Differences in microstructural architecture were investigated using Tract-Based Spatial Statistics (TBSS) and the diffusion images obtained from DTI data at D15. Permutation-based non-parametric testing was used to assess cluster significance at p < 0.05, corrected for multiple comparisons. Twelve GO patients and 11 PO patients were identified on the basis of their complaints. In PO patients, gray matter partial volume was significantly lower in several cortical and subcortical regions compared with controls, but did not differ from that of GO patients. No difference in diffusion variables was found between GO and controls. PO patients showed significantly higher mean diffusivity values than both controls and GO patients in the corpus callosum, the right anterior thalamic radiations and the superior longitudinal fasciculus, the inferior longitudinal fasciculus and the fronto-occipital fasciculus bilaterally. In conclusion, PO patients differed from GO patients by the presence of diffusion changes in long association white matter fiber tracts but not by gray matter partial volume. These results suggest that DTI at the subacute stage may be a predictive marker of poor outcome in mTBI.

Sustained attention deficit along the psychosis proneness continuum: a study on the Sustained Attention to Response Task (SART)

BACKGROUND

Sustained attention deficits have been associated with schizophrenia. However, these findings were limited to patients with schizophrenia and cannot be generalized to a wider nonclinical sample with schizotypal personality features.

OBJECTIVES

This study aimed to examine the sensitivity of a theory-driven test, the Sustained Attention Response to Task (SART), in individuals with schizotypal personality features. We also investigated the relationships between different parameters of SART and different dimensions of schizotypal features.

METHODS

One hundred and ninety-nine participants (74 individuals with schizophrenia, 69 individuals with psychometrically determined schizotypal features, and 56 healthy controls) took part in this study. Participants scoring in the top 10% of the Schizotypal Personality Questionnaire (SPQ) score were identified as having schizotypal features, and those scoring in the bottom 10% were recruited as healthy controls. All participants were administered the SART in an experimental cubicle.

RESULTS

The findings indicated that: (1) significant differences were found in SART commission error and sensitivity between the 3 experimental groups, with patients with schizophrenia and individuals with schizotypal features performing worse than healthy controls; (2) there was a trend toward statistical significance for SART efficiency score and d', with controls performing better than patients with schizophrenia and individuals with schizotypal features; (3) some associations between some SART indices and schizotypal traits were found; and (4) there was no significant relationship between SART indices and clinical symptoms in patients with schizophrenia in this study.

CONCLUSIONS

: This investigation demonstrated the potential value of a relatively new sustained attention paradigm for research in schizophrenia spectrum disorders.

Validation of the Behavioral Dyscontrol Scale-Electronic Version: Sensitivity to subtle sequelae of mild traumatic brain injury

PRIMARY OBJECTIVE

To determine whether a new computer-administered battery (Behavioral Dyscontrol Scale-Electronic Version; BDS-EV) can detect subtle executive weaknesses among individuals with a self-reported history of mild head trauma (MHT), and to compare the utility of this battery to the original, non-electronic BDS and other traditional executive measures. Both BDS-EV and BDS are comprised of three factors (motor programming, environmental independence, and fluid intelligence).

METHOD

Participants with (n = 19) and without (n = 24) MHT were compared on their performance on the BDS-EV, the non-electronic BDS, and three traditional measures of executive abilities.

RESULTS

Participants with MHT differed from those without MHT on the BDS-EV motor programming and environmental independence, but not on any other measures.

CONCLUSION

The results show that electronic administration improved the sensitivity of the battery, and support prior findings that traditional executive measures are generally insensitive to subtle executive deficits associated with chronic MHT.

The effects of mild traumatic brain injury on confrontation naming in adults

PRIMARY OBJECTIVE

To compare confrontation-naming in adults with MTBI to a group of normal adults under increased processing load conditions.

RESEARCH DESIGN

A randomized block, repeated measures design was used to examine confrontation-naming response latency and accuracy using a computerized experimental program.

METHODS AND PROCEDURES

Twenty-four adults having sustained a MTBI (aged 18-53) and 24 age-matched controls named pictures from three levels of vocabulary as quickly and accurately as possible. All MTBI participants were assessed with the Scales of Cognitive Ability for Traumatic Brain Injury (SCATBI) for later comparison.

MAIN OUTCOMES AND RESULTS

The results revealed a main effect of group ( p < or = 0.001) for the latency data and a group by vocabulary level interaction ( p = 0.043) for the accuracy data. No significant correlations were found between response latency and accuracy with performance on the SCATBI. Reaction time measures may reveal inefficiencies not tapped by traditional measures.

Characterizing 'mild' in traumatic brain injury with proton MR spectroscopy in the thalamus: Initial findings

OBJECTIVE

Although most mild traumatic brain injury (mTBI) patients suffer any of several post-concussion symptoms suggestive of thalamic involvement, they rarely present with any MRI-visible pathology. The aim here, therefore, is to characterize their thalamic metabolite levels with proton MR spectroscopy (1H-MRS) compared with healthy controls.

METHODS

T1-weighted MRI and multi-voxel 1H-MRS were acquired at 3 Tesla from 20 mTBI (Glasgow Coma Scale score of 15-13) patients, 19-59 years old, 0-7 years post-injury; and from 17 age and gender matched healthy controls. Mixed model regression was used to compare patients and controls with respect to the mean absolute N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) levels within each thalamus.

RESULTS

The mTBI-induced thalamic metabolite concentration changes were under +/- 13.0% for NAA, +/- 13.5% for Cr and +/- 18.8% for Cho relative to their corresponding concentrations in the controls: NAA: 10.08 +/- 0.30 (mean +/- standard error), Cr: 5.62 +/- 0.18 and Cho: 2.08 +/- 0.09 mM. These limits represent the minimal detectable differences between the two cohorts.

CONCLUSION

The change in metabolic levels in the thalamus of patients who sustained clinically defined mTBI could be an instrumental characteristic of 'mildness'. 1H-MRS could, therefore, serve as an objective laboratory indicator for differentiating 'mild' from more severe categories of head-trauma, regardless of the presence or lack of current clinical symptoms.

Variability in Stroop task performance and functional activation among a small brain-injured group

This study evaluated the effects of moderate to severe brain injury on cognitive task performance and cortical activation. Five participants completed a Stroop task while undergoing functional magnetic resonance imaging (fMRI) at two time points post- injury. Results revealed activation within regions typically activated during a Stroop task (the region of interest: ROI), though variability among participants was evident. Regions outside of the ROI were activated among all participants, to a greater degree than was present within the ROIs. This finding may indicate that recruitment of outside regions was necessary for successful task completion at both time points, and may suggest functional plasticity in cognitive task completion.

Long-term cognitive, emotional, and functional outcomes in trauma intensive care unit survivors without intracranial hemorrhage

BACKGROUND

Trauma patients without intracranial hemorrhage or focal neurologic deficits are typically considered low risk for lasting neuropsychological and emotional deficits, and such sequela may be overlooked, especially in those with skull fractures and concussions. We undertook this study to determine the prevalence of and risk factors for persistent cognitive impairment and emotional and functional difficulties in a sample of adult trauma intensive care unit survivors without intracranial hemorrhage.

METHODS

We queried the Vanderbilt University Trauma Registry for all patients admitted during 2003 with an Injury Severity Score >25 and a head computed tomography scan showing no intracranial hemorrhage. Of the 97 patients identified, 58 were evaluated, in person between 12 to 24 months after hospital discharge, with a comprehensive battery of cognitive, emotional, and functional instruments. The Informant Questionnaire of Cognitive Decline in the Elderly-Short Form (IQCODE-SF) was used to evaluate for pre-existing cognitive deficits in patients suspected of having cognitive impairment before their trauma.

RESULTS

A total of 33 (57%) patients were determined to have cognitive impairment, which was most pronounced in the domains of attention and executive functioning/verbal fluency. Of these patients, one (3%) was determined by the IQCODE-SF to be cognitively impaired before trauma intensive care unit hospitalization. Of the 58 patients studied, 21 (36.2%) had a concussion or skull fracture and 37 (63.8%) had neither. Cognitive impairment was significantly more likely to occur in patients who sustained a concussion or skull fracture than in trauma patients who did not (81% versus 43%; p = 0.006). Patients reported significant depressive symptoms (56%), significant symptoms of posttraumatic stress disorder (38%), and significant symptoms of anxiety (29%). Quality of life scores were lower than in the general United States population and employment difficulties were widespread. A total of 34% of patients reported being unemployed at follow-up, and cognitive impairment was more common among these patients compared with patients in the workforce (p = 0.03). Neither cognitive impairment nor emotional dysfunction was associated with age, sex, race, Injury Severity Score, blood loss, ventilatory days, or intramedullary nailing of long-bone fractures.

CONCLUSIONS

The majority of trauma survivors without intracranial hemorrhage display persistent cognitive impairment, which is nearly twice as likely in those with skull fractures or concussions. This cognitive impairment was associated with functional defects, poor quality of life, and an inability to return to work. Future research must delineate modifiable risk factors for these poor outcomes, especially in patients with skull fractures and concussions, to help improve long-term cognitive and functional status.