Comparison of executive functions and functional outcome between older patients with traumatic brain injury and normal older controls.

CONTEXT: The aim of this preliminary study was to assess the impact of traumatic brain injury (TBI) in older age on executive functioning and on their functional outcome. We also aimed to explore the influence of cognitive reserve (CR) and estimated premorbid cognitive functioning (EPCF) on these components. METHODS: A neuropsychological and functional assessment that included tests measuring Inhibition, Updating and Shifting, and functional outcome was administered to 29 patients who sustained a mild or moderate TBI in older age and a group of 24 healthy older participants. CR (level of education) and EPCF variables collected in the TBI group were associated with executive function performance and functional outcome. RESULTS: Patients with TBI obtained significantly worse performances on the spatial working memory (WM) task-reverse condition, and on the completion time of the Trails A and B than the control group. The TBI group also obtained worse functional outcome scores. A higher level of education was associated with better WM performance, and higher estimated premorbid cognitive functioning was associated with better functional outcome post TBI. CONCLUSIONS: Further studies with a larger sample should be conducted to better understand the profile and determinants of recovery from TBI in the elderly.

Longitudinal recovery of executive functions and social participation prediction following traumatic brain injury.

There is heterogeneity across studies and a lack of knowledge about recovery of EFs over time following traumatic brain injury (TBI). Also, EFs are associated with functional outcome, but there is still a gap in knowledge concerning the association between EFs and social participation following TBI. For this reason, we aim to (1) measure the recovery of the three executive function subcomponents of Miyake's model, namely flexibility, updating and inhibition between the acute phase (T1) and 6 months post TBI (T2) and (2) measure the relationship between EFs and social participation after TBI. Thus, a prospective longitudinal study that included 75 patients with TBI (mild and moderate-severe) and 50 patients with orthopedic injuries (controls) without brain damage was carried out. An extensive EFs test battery was administered at T1 and T2 whereas the Mayo-Portland Adaptability Inventory-4 (MPAI-4) was administered only at T2. In contrast with the controls, both TBI groups improved significantly between T1 and T2 on WMS-III Mental Control test (MC) and the D-KEFS Category Switching Condition of the Verbal Fluency task (SVF). Results also showed a simple time effect for the WAIS-IV Digit span and the Hayling tests. Moreover, there was an association between the SVF test and social participation (MPAI-4) at T2. In conclusion, the MC and SVF tests were found to be the best tools for measuring recovery of EFs following TBI. The SVF test was the most likely measure of EFs to give the neuropsychologist an idea of the patient's social participation.

Pitch and Rhythm Perception and Verbal Short-Term Memory in Acute Traumatic Brain Injury.

Music perception deficits are common following acquired brain injury due to stroke, epilepsy surgeries, and aneurysmal clipping. Few studies have examined these deficits following traumatic brain injury (TBI), resulting in an under-diagnosis in this population. We aimed to (1) compare TBI patients to controls on pitch and rhythm perception during the acute phase; (2) determine whether pitch and rhythm perception disorders co-occur; (3) examine lateralization of injury in the context of pitch and rhythm perception; and (4) determine the relationship between verbal short-term memory (STM) and pitch and rhythm perception. Music perception was examined using the Scale and Rhythm tests of the Montreal Battery of Evaluation of Amusia, in association with CT scans to identify lesion laterality. Verbal short-term memory was examined using Digit Span Forward. TBI patients had greater impairment than controls, with 43% demonstrating deficits in pitch perception, and 40% in rhythm perception. Deficits were greater with right hemisphere damage than left. Pitch and rhythm deficits co-occurred 31% of the time, suggesting partly dissociable networks. There was a dissociation between performance on verbal STM and pitch and rhythm perception 39 to 42% of the time (respectively), with most individuals (92%) demonstrating intact verbal STM, with impaired pitch or rhythm perception. The clinical implications of music perception deficits following TBI are discussed.

Multidimensional Psychoeducative and Counseling Intervention (SAAM) for Symptomatic Patients With Mild Traumatic Brain Injury: A Pilot Randomized Controlled Trial.

OBJECTIVE: To estimate feasibility and explore the treatment effect of a psychoeducative and counseling intervention program targeting 4 postconcussion symptoms (SAAM: Sleep/fatigue, Attention, Anxiety/mood, Memory). SETTING: Level 1 trauma center. PARTICIPANTS: Twenty-five patients with postconcussion symptoms enrolled 1 to 3 months post-accident. DESIGN: Parallel-group (experimental and wait-list control), randomized controlled trial, with masked outcome assessment the week following the last intervention session. The Experimental group received the SAAM intervention (1 session/week during 4 weeks); care as usual was maintained for both groups. MAIN MEASURE: Rivermead Post-concussion Symptoms Questionnaire (RPQ). SECONDARY MEASURES: Hospital Anxiety and Depression Scale (HADS-A/-D); Pittsburgh Sleep Quality Index (PSQI); Multidimensional Fatigue Inventory (MFI); attention and memory neuropsychological battery; Community Integration Questionnaire (CIQ). TOLERABILITY MEASURE: A 10-item satisfaction questionnaire for the experimental group. RESULTS: 15.67% of the participants evaluated for eligibility were randomized and completed the evaluation at T0. High rates of satisfaction regarding the SAAM intervention were found in the experimental group (n = 10). One participant (experimental group) withdrew after T0. Exploratory results showed that the group × time interaction was not significant, but had a large effect size for the RPQ (P = .051, η2 = .16) and HADS-D (P = .052, η2 = 0.17), and a significant interaction was found with a large effect size for the PSQI (P = .017, η2 = .24) and MFI (P = .041, η2 = .18). Post-hoc analyses revealed a significant reduction of these variables post-intervention. No significant group × time interaction was observed for cognitive measures and CIQ. CONCLUSION: The pilot study demonstrates the feasibility and tolerability of the SAAM intervention. Preliminary data suggest that SAAM intervention delivered post-acutely might reduce postconcussion symptoms, depression symptoms, fatigue, and sleep difficulties. A larger scale randomized control trial is warranted to confirm these promising results.

Relationship between depression, community integration and life satisfaction following mild traumatic brain injury.

Purpose: Compared to studies on moderate and severe traumatic brain injury (TBI), less literature exists concerning the consequences of mild traumatic brain injury (mTBI) on community integration and life satisfaction, especially in the early phase of recovery. Moreover, a better understanding of the variables that contribute to community integration and life satisfaction is still needed. The aim of the study was to assess the association of mood, fatigue and post-concussive symptoms with community integration and life satisfaction early following mTBI.Research method: A total of 85 participants aged between 18 and 61 years who sustained mTBI were included. Participants answered web-based questionnaires measuring anxiety and depression symptoms, fatigue, post-concussive symptoms, community integration and life satisfaction in the first three months post mTBI.Results: Post-concussive symptoms, fatigue and anxiety were not associated with community integration or life satisfaction. However, depressive symptoms were negatively associated with community integration and life satisfaction.Conclusions: Among all acute post-concussive symptoms following mTBI, depressive symptoms seem to have strongest relationship with community integration and life satisfaction. Acute psychological intervention targeting these symptoms is strongly recommended.

Development and description of SAAM intervention: A brief, multidimensional and psycho-educational intervention for adults with mild traumatic brain injury.

BACKGROUND: Mild traumatic brain injury (mTBI) is associated with persistent post-concussive symptoms (PCSs) in approximately 15% of cases. These symptoms can be somatic (e.g., headache), cognitive (e.g., forgetfulness, poor attention and concentration capacities), emotional (e.g., anxiety, depression, irritability) and/or sleep-arousal complaints (e.g., fatigue, sleep problems). Although practice guidelines recommend early intervention to prevent and treat PCS, we still lack an effective, standardized, integrative, post-acute intervention based on a sound and validated theoretical model. OBJECTIVES: The purpose of this article is to present the development and theoretical background underpinning a novel intervention for patients with PCSs in the post-acute phase after mTBI (1-3 months post-injury). PROCEDURE: With a biopsychosocial approach (Hou et al., 2012) and best practice recommendations, we developed a novel multidimensional intervention targeting factors that perpetuate PCSs and that can be changed with the intervention. This individual-session intervention provides practical tools for managing PCSs and is designed to provide psycho-education and reassurance, reinforce individual objectives and promote a return to activities. Each session targets one category of PCSs: Sleep/fatigue, Attention, Anxiety/depressed mood, Memory/Organization (SAAM intervention). The rationale underlying the choices of format and content for the intervention is discussed, as are the associated strengths, limitations, opportunities and challenges. CONCLUSION: This article could support researchers and clinicians to develop, replicate and/or implement interventions addressing current best practices in mTBI management.

Frontal assessment battery (FAB) performance following traumatic brain injury hospitalized in an acute care setting.

The Frontal Assessment Battery (FAB) has been shown to be useful in several clinical settings. The aim of the present study was to examine the performance of patients with traumatic brain injury (TBI) on the FAB and to predict their acute outcome. The FAB was administered to 89 patients with mild (27 = uncomplicated and 39 = complicated) and moderate (n = 23) TBI during hospitalization in an acute care setting. The length of stay in days (LOS), Glasgow Outcome Scale-Revised score (GOSE) and Disability Rating Scale (DRS) score were collected. Results showed no significant differences between the three groups on the FAB score, but age and education were significantly associated with the FAB score. Parietal lesions were associated with lower total FAB score, and with the Similarities, Motor series and Conflicting instructions subscales, while frontal lesions were associated with lower performance on the Motor series and Conflicting instructions subscales. Total FAB score was significantly correlated with all outcome measures, and together the FAB total score and the Glasgow Coma Scale (GCS) score explained 30.8% of the variance in the DRS score. The FAB may be useful clinically to acutely assess frontal and parietal lobe functions at bedside in patients with TBI and, in combination with the GCS score to measure TBI severity, can enable clinicians to predict early outcome.

Sensitivity to Binocular Disparity is Reduced by Mild Traumatic Brain Injury.

Purpose: The impairment of visual functions is one of the most common complaints following mild traumatic brain injury (mTBI). Traumatic brain injury-associated visual deficits include blurred vision, reading problems, and eye strain. In addition, previous studies have found evidence that TBI can diminish early cortical visual processing, particularly for second-order stimuli. We investigated whether cortical processing of binocular disparity is also affected by mTBI. Methods: In order to investigate the influence of mTBI on global stereopsis, we measured the quick Disparity Sensitivity Function (qDSF) in 22 patients with mTBI. Patients with manifest strabismus and double vision were excluded. Compared with standard clinical tests, the qDSF is unique in that it offers a quick and accurate estimate of thresholds across the whole spatial frequency range. Results: Results show that disparity sensitivity in the mTBI patients were significantly reduced compared with the normative dataset (n = 61). The peak spatial frequency was not affected. Conclusions: Our results suggest that the reduced disparity sensitivity in patients with mTBI is more likely caused by cortical changes (e.g., axonal shearing, or reduced interhemispheric communication) rather than oculomotor dysfunction.

First- and second-order contrast sensitivity functions reveal disrupted visual processing following mild traumatic brain injury.

Vision is disrupted by traumatic brain injury (TBI), with vision-related complaints being amongst the most common in this population. Based on the neural responses of early visual cortical areas, injury to the visual cortex would be predicted to affect both 1(st) order and 2(nd) order contrast sensitivity functions (CSFs)-the height and/or the cut-off of the CSF are expected to be affected by TBI. Previous studies have reported disruptions only in 2(nd) order contrast sensitivity, but using a narrow range of parameters and divergent methodologies-no study has characterized the effect of TBI on the full CSF for both 1(st) and 2(nd) order stimuli. Such information is needed to properly understand the effect of TBI on contrast perception, which underlies all visual processing. Using a unified framework based on the quick contrast sensitivity function, we measured full CSFs for static and dynamic 1(st) and 2(nd) order stimuli. Our results provide a unique dataset showing alterations in sensitivity for both 1(st) and 2(nd) order visual stimuli. In particular, we show that TBI patients have increased sensitivity for 1(st) order motion stimuli and decreased sensitivity to orientation-defined and contrast-defined 2(nd) order stimuli. In addition, our data suggest that TBI patients' sensitivity for both 1(st) order stimuli and 2(nd) order contrast-defined stimuli is shifted towards higher spatial frequencies.

Shedding light on the effect of priority instructions during dual-task performance in younger and older adults: A fNIRS study.

Age-related differences in the ability to perform two tasks simultaneously (or dual-task) have become a major concern in aging neurosciences and have often been assessed with two distinct paradigms; the Psychological Refractory Period (PRP) and the Dual-Task (DT) paradigms. PRP studies assess participants when they give Priority to one task over the other (complete A then B), whereas in DT studies participants give Equal priority to both tasks (complete A and B). The Equal condition could be viewed as adding an executive control component to the task since the participants must spontaneously monitor attention between tasks. In the current study, we assessed the effect of priority instructions (Priority vs. Equal) on the dual-task performance and brain activity of younger (n = 16) and older adults (n = 19) with functional near infra-red spectroscopy (fNIRS). In younger adults, the Priority condition showed right-sided activation in the prefrontal cortex during DT execution. Older adults showed bilateral frontal activation, yet restrained to specific areas. They showed increased activation in DT vs. single task condition in the left dorsolateral prefrontal cortex (DLPFC) and the bilateral ventrolateral prefrontal cortex (VLPFC). In the Equal condition, the DT condition showed isolated left DLPFC and VLPFC activation in younger adults and widespread bilateral DLPFC activation in older adults. These results suggest that for both older and younger adults, priority effects are associated with distinct patterns of prefrontal activation. Age-related differences also exist in these patterns such that prefrontal activation seems to be more spread out at different sites in older adults when they are instructed to give Equal priority to both tasks.

Inter-hemispheric wave propagation failures in traumatic brain injury are indicative of callosal damage.

Approximately 3.2-5.3 million Americans live with the consequences of a traumatic brain injury (TBI), making TBI one of the most common causes of disability in the world. Visual deficits often accompany TBI but physiological and anatomical evidence for injury in mild TBI is lacking. Axons traversing the corpus callosum are particularly vulnerable to TBI. Hemifield representations of early visual areas are linked by bundles of fibers that together cross the corpus callosum while maintaining their topographic relations. Given the increased vulnerability of the long visual axons traversing the corpus callosum, we hypothesized that inter-hemispheric transmission for vision will be impaired following mild TBI. Using the travelling wave paradigm (Wilson, Blake, & Lee 2001), we measured inter-hemispheric transmission in terms of both speed and propagation failures in 14 mild TBI patients and 14 age-matched controls. We found that relative to intra-hemispheric waves, inter-hemispheric waves were faster and that the inter-hemispheric propagation failures were more common in TBI patients. Furthermore, the transmission failures were topographically distributed, with a bias towards greater failures for transmission across the upper visual field. We discuss the results in terms of increased local inhibition and topographically-selective axonal injury in mild TBI.

Individual differences effects on the psychological refractory period.

The goal of this study was to assess the impact of individual neuropsychological differences on the ability to share attention between concurrent tasks. Participants (n = 20) were trained on six single task practice sessions and dual-task was assessed with reaction time performance on a psychological refractory period (PRP) paradigm. Neuropsychological test scores were also acquired. Furthermore, one of the known variables that can influence performances on neuropsychological tests is gender, which was added as a potential predictor. Results show that the small PRP group was associated with better performances in processing speed, inhibition, flexibility and working memory on neuropsychological tests. Gender also had an impact on the PRP, males having a lower PRP than females. A multiple regression was performed to determine which variables explained the most PRP duration, which showed that 49.1% of the variance of the PRP length could be explained by gender, reaction times of the PRP practice trials at the sixth session, the denomination and flexibility conditions of the Modified Stroop Task as well as results on the Symbol Search Test. Gender was the variable that explained the PRP variance the most (23%). Processing speed also seemed to be a great determinant of the PRP as well as the ability to alternate between task-sets as assessed by the Flexibility condition of the Modified Stroop Task. Thus, this study reveals that good performances on certain neuropsychological tests could predict one's ease to manage two tasks simultaneously with a higher chance for males to perform better.

A fNIRS investigation of switching and inhibition during the modified Stroop task in younger and older adults.

Brain imaging studies have reported age-related differences in brain activation for attentional control functions, such as inhibition and task-switching. However, age-related differences in brain activation patterns in more than one attentional control task have rarely been studied in the same group of participants. In this study, younger and older adults completed a modified Stroop task with interference and switching conditions, using functional near infra-red spectroscopy. While interference did not reveal any significant activation of the prefrontal cortex in younger adults, switching produced an increased activation bilaterally in both the anterior dorsolateral prefrontal cortex (DLPFC) and the anterior ventrolateral prefrontal cortex (VLPFC). In older adults, an isolated right and left anterior DLPFC activation was observed even in the non-executive conditions of the Stroop task (color denomination) and the interference condition revealed activation mostly in the posterior left DLPFC and bilateral VLPFC with a small right anterior DLPFC component. Specific to older adults, switching induced an increased activation spread out bilaterally over the prefrontal cortex in the bilateral anterior DLPFC, the posterior left DLPFC and bilateral VLPFC. These results suggest that for both older and younger adults, inhibition and switching are associated with distinct patterns of prefrontal activation and that age-related differences exist in these patterns such that prefrontal activation seems to be more spread out at different sites in older adults.

Learning to bypass the central bottleneck: declining automaticity with advancing age.

Does advancing age reduce the ability to bypass the central bottleneck through task automatization? To answer this question, the authors asked 12 older adults and 20 young adults to first learn to perform an auditory-vocal task (low vs. high pitch) in 6 single-task sessions. Their dual-task performance was then assessed with a psychological refractory period paradigm, in which the highly practiced auditory-vocal task was presented as Task 2, along with an unpracticed visual-manual Task 1. Converging evidence indicated qualitative differences in dual-task performance with age: Whereas the vast majority of young adults bypassed the bottleneck, at most 1 of the 12 older adults was able to do so. Older adults are either reluctant to bypass the bottleneck (as a matter of strategy) or have lost the ability to automatize task performance.

Bypassing the central bottleneck after single-task practice in the psychological refractory period paradigm: evidence for task automatization and greedy resource recruitment.

In this research, the controversial issue of whether the central bottleneck can be bypassed through task automatization was investigated. To examine this issue, participants received six single-task practice sessions with an auditory-vocal task (low vs. high pitch). We then assessed dual-task performance using the analytically tractable psychological refractory period (PRP) paradigm, in which the highly practiced auditory-vocal task was presented as Task 2, along with an unpracticed visual-manual Task 1. The results provide evidence of bottleneck bypass for virtually all the participants (17 out of 20). Several converging tests suggest that the bottleneck reemerged, however, in a follow-up experiment with tasks presented in the opposite order (auditory-vocal Task 1 and visual-manual Task 2). One possible explanation is that tasks greedily recruit central resources when available, even though they can operate without central resources when unavailable.

An electrophysiological study of mood, modal context, and anaphora.

We investigated whether modal information elicited empirical effects with regard to discourse processing. That is, like tense information, one of the linguistic factors shown to be relevant in organizing a discourse representation is modality, where the mood of an utterance indicates whether or not it is asserted. Event-related potentials (ERPs) were used in order to address the question of the qualitative nature of discourse processing, as well as the time course of this process. This experiment investigated pronoun resolution in two-sentence discourses, where context sentences either contained a hypothetical or actual Noun Phrase antecedent. The other factor in this 2x2 experiment was type of continuation sentence, which included or excluded a modal auxiliary (e.g., must, should) and contained a pronoun. Intuitions suggest that hypothetical antecedents followed by pronouns asserted to exist present ungrammaticality, unlike actual antecedents followed by such pronouns. Results confirmed the grammatical intuition that the former discourse displays anomaly, unlike the latter (control) discourse. That is, at the Verb position in continuation sentences, we found frontal positivity, consistent with the family of P600 components, and not an N400 effect, which suggests that the anomalous target sentences caused a revision in discourse structure. Furthermore, sentences exhibiting modal information resulted in negative-going waveforms at other points in the continuation sentence, indicating that modality affects the overall structural complexity of discourse representation.