Interactions between divided attention and working-memory load in patients with severe traumatic brain injury

The Role of Neuropsychology in Traumatic Brain Injury: Comprehensive Literature Review

Traumatic brain injury (TBI) is a major public health concern, often leading to significant behavioral and cognitive changes with subsequent impairment in daily functioning and personal interactions. The management of TBI involves a multidisciplinary approach. Neuropsychology has emerged as a critical discipline in assessing, diagnosing, treating, and rehabilitating individuals with TBI. Successful management also requires careful consideration of the patient's cognitive status. Therefore, clinicians must have a comprehensive understanding of the overall clinical picture of the patient at the cognitive and physical level. The primary aim of this research is to explore the role of neuropsychology in TBI management and rehabilitation thoroughly while providing an updated review of the literature. Various neuropsychological assessment tools used to evaluate cognitive functioning in individuals with TBI will be discussed in addition to their validity, reliability, and usefulness in identifying cognitive deficits and developing individualized treatment plans. The findings in this article will have significant implications on the clinical practice of neuropsychology in TBI patients, highlighting the importance of neuropsychological assessment in optimizing the management of this population. The need for increased awareness of neuropsychology among health care professionals, especially in the acute hospital setting, is growing along with the increase in diagnosis of TBI and its complications. Adequate understanding of the complex interplay between cognitive, emotional, and behavioral factors in TBI can inform the development of new interventions and treatment strategies, making it equally as important for patients and their families.

Neuropsychological Assessment in Patients with Traumatic Brain Injury: A Comprehensive Review with Clinical Recommendations

Traumatic brain injury is damage to the brain occurring after birth, often resulting in the deterioration of cognitive, behavioural, and emotional functions. Neuropsychological evaluation can assist clinicians to better assess the patient's clinical condition, reach differential diagnoses, and develop interventional strategies. However, considering the multiple rating scales available, it is not easy to establish which tool is most suitable for the different brain injury conditions. The aim of this review is to investigate and describe the most used neurocognitive assessment tools in patients with traumatic brain injury to provide clinicians with clear indications on their use in clinical practice. Indeed, during the acute phase, after the head trauma, alertness and wakefulness of the patients affected by a disorder of consciousness can be assessed using different scales, such as the Coma Recovery Scale-Revised. In both postacute and chronic phases after traumatic brain injury, general cognitive assessment tools (such as the Mini Mental State Examination) or more specific cognitive tests (e.g., Wisconsin Card Sorting Test and Trail Making Test) could be administered according to the patient's functional status. In this way, clinicians may be aware of the patient's neuropsychological and cognitive level, so they can guarantee a personalized and tailored rehabilitation approach in this frail patient population.

INCOG 2.0 Guidelines for Cognitive Rehabilitation Following Traumatic Brain Injury, Part II: Attention and Information Processing Speed

INTRODUCTION

Moderate to severe traumatic brain injury (MS-TBI) commonly causes disruption in aspects of attention due to its diffuse nature and injury to frontotemporal and midbrain reticular activating systems. Attentional impairments are a common focus of cognitive rehabilitation, and increased awareness of evidence is needed to facilitate informed clinical practice.

METHODS

An expert panel of clinicians/researchers (known as INCOG) reviewed evidence published from 2014 and developed updated guidelines for the management of attention in adults, as well as a decision-making algorithm, and an audit tool for review of clinical practice.

RESULTS

This update incorporated 27 studies and made 11 recommendations. Two new recommendations regarding transcranial stimulation and an herbal supplement were made. Five were updated from INCOG 2014 and 4 were unchanged. The team recommends screening for and addressing factors contributing to attentional problems, including hearing, vision, fatigue, sleep-wake disturbance, anxiety, depression, pain, substance use, and medication. Metacognitive strategy training focused on everyday activities is recommended for individuals with mild-moderate attentional impairments. Practice on de-contextualized computer-based attentional tasks is not recommended because of lack of evidence of generalization, but direct training on everyday tasks, including dual tasks or dealing with background noise, may lead to gains for performance of those tasks. Potential usefulness of environmental modifications is also discussed. There is insufficient evidence to support mindfulness-based meditation, periodic alerting, or noninvasive brain stimulation for alleviating attentional impairments. Of pharmacological interventions, methylphenidate is recommended to improve information processing speed. Amantadine may facilitate arousal in comatose or vegetative patients but does not enhance performance on attentional measures over the longer term. The antioxidant Chinese herbal supplement MLC901 (NeuroAiD IITM) may enhance selective attention in individuals with mild-moderate TBI.

CONCLUSION

Evidence for interventions to improve attention after TBI is slowly growing. However, more controlled trials are needed, especially evaluating behavioral or nonpharmacological interventions for attention.

Rationale and methodology for examining the acute effects of aerobic exercise combined with varying degrees of virtual reality immersion on cognition in persons with TBI

Persons with Traumatic Brain Injury (TBI) commonly present with long-term cognitive deficits in executive function, processing speed, attention, and learning and memory. While specific cognitive rehabilitation techniques have shown significant success for deficits in individual domains, aerobic exercise training represents a promising approach for an efficient and general treatment modality that might improve many cognitive domains concurrently. Existing studies in TBI report equivocal results, however, and are hampered by methodological concerns, including small sample sizes, uncontrolled single-group designs, and the use of suboptimal exercise modalities for eliciting cognitive improvements in this population. One particularly promising modality involves the application of environmental enrichment via virtual reality (VR) during aerobic exercise in persons with TBI, but this has yet to be investigated. One approach for systematically developing an optimal aerobic exercise intervention for persons with TBI involves the examination of single bouts of aerobic exercise (i.e., acute aerobic exercise) on cognition. Acute exercise research is a necessary first step for informing the development of high-quality exercise training interventions that are more likely to induce meaningful beneficial effects. To date, such an acute exercise paradigm has yet to be conducted in persons with TBI. To that end, we propose an acute exercise study that will investigate the acute effects of aerobic exercise with incremental degrees of environmental enrichment (VR) relative to a control comparison condition on executive function (divided attention and working memory) and processing speed in 24 people with TBI.

Moving Toward Accurate Assessment of Working Memory in Adults With Neurogenically Based Communication Disorders

Purpose This article presents a viewpoint highlighting concerns regarding currently available assessments of working memory in adults with neurogenic communication disorders. Additionally, we provide recommendations for improving working memory assessment in this population. Method This viewpoint includes a critique of clinical and experimental working memory tests relevant to speech-language pathologists. We consider the terminology used to describe memory, as well as discuss language demands and test construction. Results Clinical and experimental testing of working memory in adults with neurogenic communication disorders is challenged due to theoretical, methodological, and practical limitations. The major limitations are characterized as linguistic and task demands, presentation and response modality effects, test administration, and scoring parameters. Taking these limitations into consideration, several modifications to working memory testing and their relevance to neurogenic populations are discussed. Conclusions The recommendations provided in this article can better guide clinicians and researchers to advocate for improved tests of working memory in adults with neurogenic communication disorders. Future research should continue to address these concerns and consider our recommendations.

The association between dual-task walking and counting responses and cognitive function and disability after severe head injury: A preliminary study

Adverse outcomes after severe head injury (SHI) can be difficult to detect in primary care and other settings where there is not specialist expertise for interpretation. Walking and counting dual-task (DT) measures are strongly associated with cognitive impairment and dementia and this preliminary study investigates whether performance on DT walking and counting tasks are associated with cognitive function and disability in 125 participants who sustained a SHI on average 26 years before. Single Task (ST) walking (speed over 6 metres) and ST counting (Serial 3s) and DT performance of concurrent walking and Serial 3s were compared with neuropsychological, wellbeing and disability tests for strength of association. The strongest correlations were between ST Correct Cognitive Responses (CCRs) and MMSE (rho = 0.435), DT CCRs and Short-term Memory Binding Tests (STMBT) binding accuracy (rho = 0,409) and DT CCRs and STROOP (rho = 0.420), but associations were less strong with disability. Developing this test, as a cost-efficient screening tool for triage to onward referral for neuropsychological assessment, holds promise, but requires further research.

Executive (dys)function after traumatic brain injury: special considerations for behavioral pharmacology

Executive function is an umbrella term that includes cognitive processes such as decision-making, impulse control, attention, behavioral flexibility, and working memory. Each of these processes depends largely upon monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in the frontal cortex, striatum, and hippocampus, among other brain areas. Traumatic brain injury (TBI) induces disruptions in monoaminergic signaling along several steps in the neurotransmission process - synthesis, distribution, and breakdown - and in turn, produces long-lasting deficits in several executive function domains. Understanding how TBI alters monoamingeric neurotransmission and executive function will advance basic knowledge of the underlying principles that govern executive function and potentially further treatment of cognitive deficits following such injury. In this review, we examine the influence of TBI on the following measures of executive function - impulsivity, behavioral flexibility, and working memory. We also describe monoaminergic-systems changes following TBI. Given that TBI patients experience alterations in monoaminergic signaling following injury, they may represent a unique population with regard to pharmacotherapy. We conclude this review by discussing some considerations for pharmacotherapy in the field of TBI.

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.

White matter integrity of the medial forebrain bundle and attention and working memory deficits following traumatic brain injury

BACKGROUND AND OBJECTIVE

The medial forebrain bundle (MFB) contains ascending catecholamine fibers that project to the prefrontal cortex (PFC). Damage to these fibers following traumatic brain injury (TBI) may alter extracellular catecholamine levels in the PFC and impede attention and working memory ability. This study investigated white matter microstructure of the medial MFB, specifically the supero-lateral branch (slMFB), following TBI, and its association with performance on attention and working memory tasks.

METHOD

Neuropsychological measures of attention and working memory were administered to 20 moderate-severe participants with TBI (posttraumatic amnesia M = 40.05 ± 37.10 days, median time since injury 10.48 months, range 3.72-87.49) and 20 healthy controls. Probabilistic tractography was used to obtain fractional anisotropy (FA) and mean diffusivity (MD) values for 17 participants with TBI and 20 healthy controls.

RESULTS

When compared to controls, participants with TBI were found to have significantly lower FA (p < .001) and higher MD (p < .001) slMFB values, and they were slower to complete tasks including Trail Making Task-A, Hayling, selective attention task, n-back, and Symbol Digit Modalities Test.

CONCLUSION

This study was the first to demonstrate microstructural white matter damage within the slMFB following TBI. However, no evidence was found for an association of alterations to this tract and performance on attentional tasks.

Concomitant Use of Transcranial Direct Current Stimulation and Computer-Assisted Training for the Rehabilitation of Attention in Traumatic Brain Injured Patients: Behavioral and Neuroimaging Results

Divided attention (DA), the ability to distribute cognitive resources among two or more simultaneous tasks, may be severely compromised after traumatic brain injury (TBI), resulting in problems with numerous activities involved with daily living. So far, no research has investigated whether the use of non-invasive brain stimulation associated with neuropsychological rehabilitation might contribute to the recovery of such cognitive function. The main purpose of this study was to assess the effectiveness of 10 transcranial direct current stimulation (tDCS) sessions combined with computer-assisted training; it also intended to explore the neural modifications induced by the treatment. Thirty-two patients with severe TBI participated in the study: 16 were part of the experimental group, and 16 part of the control group. The treatment included 20’ of tDCS, administered twice a day for 5 days. The electrodes were placed on the dorso-lateral prefrontal cortex. Their location varied across patients and it depended on each participant’s specific area of damage. The control group received sham tDCS. After each tDCS session, the patient received computer-assisted cognitive training on DA for 40’. The results showed that the experimental group significantly improved in DA performance between pre- and post-treatment, showing faster reaction times (RTs), and fewer omissions. No improvement was detected between the baseline assessment (i.e., 1 month before treatment) and the pre-training assessment, or within the control group. Functional magnetic resonance imaging (fMRI) data, obtained on the experimental group during a DA task, showed post-treatment lower cerebral activations in the right superior temporal gyrus (BA 42), right and left middle frontal gyrus (BA 6), right postcentral gyrus (BA 3) and left inferior frontal gyrus (BA 9). We interpreted such neural changes as normalization of previously abnormal hyperactivations.

Clinical significance of an easy-to-use dual task for assessing inattention

Purpose To investigate clinical significance of a newly developed paper-and-pencil type dual-task (Oiso-DT) for assessing inattention of brain-damaged patients. Methods A total of 134 healthy individuals and 44 patients with traumatic brain injury (TBI) were the subjects. Oiso-DT combined a cancelation sub-task and a written calculation sub-task on paper. The performance was scored based on the correct rate (CR) and success rate in the cancelation sub-task, and the number of correct answers and CR in the calculation sub-task for three minutes. Performances of Clinical Assessment for Attention (CAT) developed by The Japan Society for Higher Brain Dysfunction were also measured in TBI patients. Results Based on a simple and unique definition of cutoff values, abnormal performance was detected more often in the Oiso-DT than in any sub-task of CAT including Symbol Digit Modalities Test, The Memory Updating Test and Paced Auditory Serial Addition Task, etc. although the specificity was comparable. Conclusion This easy-to-use Oiso-DT might be valuable and sensitive for detecting inattention including mild deficit. Implications for Rehabilitation The Oiso-DT, a paper-and-pencil clinical test for assessing inattention demonstrates higher sensitivity for traumatic-brain-injury patients than standard neuropsychological tests. The task performance is evaluated by a simple and unique method without specific equipment or even a personal computer. The Oiso-DT might be valuable for detecting inattention including mild deficit. The Oiso-DT is easily applicable to patients with severe inattention who failed to complete complex tasks like paced auditory serial addition task.