The relationship between working memory, processing speed, verbal comprehension and FAS performance following traumatic brain injury

Insights into social communication following traumatic brain injury sustained in older adulthood

BACKGROUND

There is a lack of evidence relating to cognitive-communication difficulties following traumatic brain injury (TBI) sustained in older adulthood. A prominent area in which post-TBI cognitive-communication difficulties manifest is at the level of social communication. An investigation of social communication focusing on comparison of those injured in older and younger adulthood is a practical starting point for age-related cognitive-communication outcome comparison.

AIMS

The overall objective of this study was to explore the social communication of individuals who sustained severe TBI in an early period of older adulthood (50-70 years) compared to younger adulthood (18-40 years), as informed by self and close other reports.

METHODS & PROCEDURES

This exploratory controlled group comparison study involved analysis of self-reported and close other reported La Trobe Communication Questionnaire data for 22 adults with severe TBI (11 older at injury; 11 younger at injury) and 22 control participants (11 older; 11 younger). TBI participants were matched for injury variables and participant groups were matched for sex, age and education.

OUTCOMES & RESULTS

The close others of the older and younger adults with TBI reported them to have significantly more frequent difficulty with social communication than the close others of age-matched control groups. Older adults with TBI reported significantly more frequent difficulty with social communication than uninjured older adults. In contrast, younger adults with TBI and uninjured younger adults reported a similar frequency of difficulty with social communication. No age-based difference in the frequency of social communication difficulty was evident when comparing the self or close other reports of older and younger adults with TBI. Awareness of social communication difficulty, as indexed by comparing self and close other perceptions, showed a different pattern across the TBI groups. The older TBI group rated themselves as having significantly less frequent social communication difficulty than was perceived by their close others. In contrast, no statistically significant difference was evident between the self and close other social communication ratings of the younger TBI group.

CONCLUSIONS AND IMPLICATIONS

Where possible clinicians need to work with close communication partners to understand the nature and degree of social communication difficulty following severe TBI. This may be especially important when working with people who sustain TBI in older adulthood if future research shows that this population have greater difficulty with self-awareness of social communication difficulty.

WHAT THIS PAPER ADDS

What is already known on the subject Cognitive-communication difficulties are a common consequence of traumatic brain injury (TBI) that can have long-term impact on everyday functioning. These challenges have primarily been investigated in individuals who sustained TBI in younger adulthood. What this paper adds to existing knowledge Individuals who sustain severe TBI in early older adulthood have a higher frequency of reported social communication difficulty to non-injured adults of a similar age, albeit they may underreport such difficulties potentially in the context of reduced self-awareness. What are the potential or actual clinical implications of this work? Social communication difficulty is an issue for people who sustain severe TBI in early older adulthood. However, a poorer overall social communication outcome in comparison to those injured in younger adulthood should not be assumed. Clinical service delivery for these challenges is most optimally delivered in a collaborative manner with the individual and their close others. Future research is required to investigate the identified trends from this study.

Computed tomography findings as early predictors of long-term language impairment in patients with traumatic brain injury

This study aims to assess the relationship between computed tomography (CT) findings, during the acute phase of hospitalization, and long-term language impairment in people with traumatic brain injury (TBI). Another aim was to assess the receptive and expressive abilities of subjects with TBI based on the location of the injury. This is a retrospective observational study including 49 participants with TBI due to war injuries. The Arabic Diagnostic Aphasia Battery (A-DAB-1) was administered to the participants and the Helsinki CT score was computed to quantify brain damage. The results showed that the Helsinki CT score was negatively correlated with the total score of the A-DAB-1 (r = -0.544, p-value < 0.0001). Simple linear regression supported such findings and reflected an inversely proportional relationship between both variables (p-value < 0.0001). When compared with subjects having right hemisphere damage, subjects with left hemisphere and bilateral brain damage performed more poorly on language tasks respectively as follows: A-DAB-1 overall score (92.08-66.08-70.28, p-value = 0.021), Content of descriptive speech (9.57-6.69-7.22, p-value = 0.034), Verbal fluency (6.57-3.54-3.89, p-value = 0.002), Auditory comprehension (9.71-7.54-7.78, p-value = 0.039), Complex auditory commands (9.71-7.65-7.56, p-value = 0.043), Repetition (9.75-7.08-7.61, p-value = 0.036), Naming (9.93-7.15-8.11, p-value = 0.046). Following TBI, CT findings on admission can significantly predict long-term language abilities, with left side lesions inducing poorer outcomes.

A true reflection of executive functioning or a representation of task-specific variance? Re-evaluating the unity/diversity framework

The unity/diversity framework, originally published by Miyake et al. (2000) has become the most cited model of executive functioning. Consequently, when researchers operationalise executive function (EF) they often exclusively assess the three "core" EFs: updating, shifting, and inhibition. However, rather than core EFs representing domain general cognitive abilities, these three EFs may instead represent specific procedural skills from the overlapping methodologies of the tasks selected. In this study, we conducted a confirmatory factor analysis (CFA) which showed both the traditional three-factor and nested-factor model from the unity/diversity framework failed to reach satisfactory levels of fit. Subsequently, an exploratory factor analysis supported a three-factor model reflecting: an expanded working memory factor, a combined shifting/inhibition factor representing cognitive flexibility, and a factor comprised solely of the Stroop task. These results demonstrate that working memory remains the most robustly operationalised EF construct, whereas shifting and inhibition may represent task-specific mechanisms of a broader domain-general cognitive flexibility factor. Ultimately, there is little evidence to suggest that updating, shifting, and inhibition encapsulates all core EFs. Further research is needed to develop an ecologically valid model of executive functioning that captures the cognitive abilities associated with real world goal-directed behaviour.

Verbal fluency difficulties in aphasia: A combination of lexical and executive control deficits

BACKGROUND

Verbal fluency tasks are routinely used in clinical assessment and research studies of aphasia. People with aphasia produce fewer items in verbal fluency tasks. It remains unclear if their output is limited solely by their lexical difficulties and/or has a basis in their executive control abilities. Recent research has illustrated that detailed characterization of verbal fluency performance using temporal characteristics of words retrieved, clustering and switching, and pause durations, along with separate measures of executive control stands to inform our understanding of the lexical and cognitive underpinnings of verbal fluency in aphasia.

AIMS

To determine the locus of the verbal fluency difficulties in aphasia, we compared semantic and letter fluency trials between people with aphasia and healthy control participants using a wide range of variables to capture the performance between the two groups. The groups were also tested on separate measures of executive control to determine the relationship amongst these tasks and fluency performance.

METHODS & PROCEDURES

Semantic (animal) and letter (F, A, S) fluency data for 60s trials were collected from 14 people with aphasia (PWA) and 24 healthy adult controls (HC). Variables, such as number of correct responses, clustering and switching analyses, were performed along with temporal measures of the retrieved words (response latencies) and pause durations. Participants performed executive control tasks to measure inhibitory control, mental-set shifting and memory span.

OUTCOMES & RESULTS

Compared with HC, PWA produced fewer correct responses, showed greater difficulty with the letter fluency condition, were slower in getting started with the trials, showed slower retrieval times as noted in within- and between-cluster pause durations, and switched less often. Despite these retrieval difficulties, PWA showed a similar decline in the rate of recall to HC, and had similar cluster size. Executive control measures correlated primarily with the letter fluency variables: mostly for PWA and in one instance for HC.

CONCLUSIONS & IMPLICATIONS

Poorer performance for PWA is a combination of difficulties in both the lexical and executive components of the verbal fluency task. Our findings highlight the importance of detailed characterization of fluency performance in deciphering the underlying mechanism of retrieval difficulties in aphasia, and illustrate the importance of using letter fluency trials to tap into executive control processes.

WHAT THIS PAPER ADDS

What is already known on the subject PWA typically show impaired performance in verbal fluency tasks. It is debated whether this impaired performance is a result of their lexical difficulties or executive control difficulties, or a combination of both. This debate continues because previous studies have mostly used semantic fluency condition without including letter fluency condition; used a limited range of variables (e.g., number of correct responses); and not included separate executive control measures to explain the performance pattern in aphasia. This research addresses these outstanding issues to determine the specific contribution of lexical and executive control processes in verbal fluency in aphasia by including: both semantic and letter fluency conditions; a wide range of variables to identify the relative contribution of lexical and executive control mechanisms; and independent measures of executive control. What this paper adds to existing knowledge Using the multidimensional analysis approach for verbal fluency performance from both semantic and letter fluency conditions, this is the first study to systematically demonstrate that PWA had difficulties in both lexical and executive control components of the task. At the individual level, PWA had greater difficulty on the letter fluency condition compared with semantic fluency. We observed significant correlations between the executive control measures and verbal fluency measures primarily for the letter fluency condition. This research makes a significant contribution to our understanding of lexical and executive control aspects in word production in aphasia. What are the potential or actual clinical implications of this work? From a clinical perspective, this research highlights the importance of using a full range of verbal fluency and executive control measures to tap into the lexical as well as executive control abilities of PWA, and also the utility of using letter fluency to tap into the executive control processes in PWA.

Cognitive profile of mild traumatic brain injury patients requiring acute hospitalization - A UC davis cognitive screener (UCD-Cog) study

OBJECTIVE

Identification of patients with mTBI at risk for developing persistent-post concussive syndromes should begin during the ED/inpatient evaluation due to frequent lack of post-discharge follow-up. The best method for evaluating cognitive deficits in these acute settings and how to utilize this information to optimize follow-up care is a matter of ongoing research. In this descriptive study, we present the cognitive profile of 214 hospitalized patients with mTBI using a novel cognitive and behavioral screener, the UCD-Cog.

METHOD

A retrospective review of patients with mTBI requiring hospitalization who were enrolled in the UC Davis TBI Registry over the course of 1 year.

RESULTS

Reasoning, executive function, and delayed recall were the most frequently impaired cognitive domains. GCS 13-14 was associated with higher numbers of impaired cognitive domains and frequencies of impairments in domains traditionally associated with post-concussive symptoms. Patients with abnormal UCD-Cog results, regardless of GCS, were recommended higher levels of post-discharge care and supervision.

CONCLUSION

Inpatient cognitive profiles using the UCD-Cog were consistent with evaluations during the subacute/chronic phase of mTBI and supports the clinical utility of acute cognitive screeners for mTBI management. Future studies will determine how the acute cognitive assessments correlate with long-term mTBI outcomes.

Lexical and Cognitive Underpinnings of Verbal Fluency: Evidence from Bengali-English Bilingual Aphasia

Research in bilingual healthy controls (BHC) has illustrated that detailed characterization of verbal fluency along with separate measures of executive control stand to inform our understanding of the lexical and cognitive underpinnings of the task. Such data are currently lacking in bilinguals with aphasia (BWA). We aimed to compare the characteristics of verbal fluency performance (semantic, letter) in Bengali-English BWA and BHC, in terms of cross-linguistic differences, variation on the parameters of bilingualism, and cognitive underpinnings. BWA showed significant differences on verbal fluency variables where executive control demands were higher (fluency difference score, number of switches, between-cluster pauses); whilst performed similarly on variables where executive control demands were lower (cluster size, within-cluster pauses). Despite clear cross-linguistic advantage in Bengali for BHC, no cross-linguistic differences were noted in BWA. BWA who were most affected in the independent executive control measures also showed greater impairment in letter fluency condition. Correlation analyses revealed a significant relationship for BWA between inhibitory control and number of correct responses, initial retrieval time, and number of switches. This research contributes to the debate of underlying mechanisms of word retrieval deficits in aphasia, and adds to the nascent literature of BWA in South Asian languages.

Attention and Communication Following TBI: Making the Connection through a Meta-Narrative Systematic Review

BACKGROUND AND AIM

Communication difficulties are one of the hallmark characteristics of adults following traumatic brain injury (TBI), a difficulty that incorporates multiple aspects of cognition and language. One aspect of cognition that impacts communication is attention. This review explores both attention and communication following moderate to severe TBI and aims to connect them through a narrative analysis of the discourse surrounding the terms and how they have evolved over time. This includes exploring and reviewing theories and specific constructs of these two aspects of cognition.

METHOD

A meta-narrative systematic literature review was completed according to RAMESES methodology.

RESULTS

A total of 37 articles were included in the review. The disciplines that populated the articles included, but were not limited to, speech language pathology (SLP) 36.5%, psychology 23.8%, and a collaboration of neuropsychology and SLP 7.9%. Of the papers that were included, 10% explored and supported theories of attention related to executive function affecting communication. Specific levels of attention were mapped onto specific communication skills with the corresponding year and authors to create a timeline and narrative of these concepts.

CONCLUSIONS

The main communication behaviours that are related to attention in the context of post-TBI cognition include discourse, tangential communication, social communication, auditory comprehension, verbal reasoning, topic maintenance, interpretation of social cues and emotions, verbal expression, reading comprehension, verbal response speed, and subvocal rehearsal.

Past Life Experiences and Neurological Recovery: The Role of Cognitive Reserve in the Rehabilitation of Severe Post-Anoxic Encephalopathy and Traumatic Brain Injury

OBJECTIVE

Patients with an equivalent clinical background may show unexpected interindividual differences in their outcome. The cognitive reserve (CR) model has been proposed to account for such discrepancies, but its role after acquired severe injuries is still being debated. We hypothesize that inappropriate investigative methods might have been used when dealing with severe patients, which have very likely reduced the possibility of observing meaningful influences in recovery from severe traumas.

METHODS

To overcome this issue, the potential neuroprotective role of CR was investigated, considering a wider spectrum of clinical symptoms ranging from low-level brain stem functions necessary for life to more complex motor and cognitive skills. In the present study, data from 50 severe patients, 20 suffering from post-anoxic encephalopathy (PAE) and 30 with traumatic brain injury (TBI), were collected and retrospectively analyzed.

RESULTS

We found that CR, diagnosis, time of hospitalization, and their interaction had an effect on the clinical indexes. When the predictive power of CR was investigated by means of two machine learning classifier algorithms, CR, together with age, emerged as the strongest factor in discriminating between patients who reached or did not reach successful recovery.

CONCLUSIONS

Overall, the present study highlights a possible role of CR in shaping the recovery of severe patients suffering from either PAE or TBI. The practical implications underlying the need to routinely considered CR in the clinical practice are discussed.

Comparison of animal, action and phonemic fluency in aphasia

BACKGROUND

The ability to generate words that follow certain constraints, or verbal fluency, is a sensitive indicator of neurocognitive impairment, and is impacted by a variety of variables.

AIMS

To investigate the effect of post-stroke aphasia, elicitation category and linguistic variables on verbal fluency performance.

METHODS & PROCEDURES

Twenty-eight persons with aphasia (PWA) with a single left-hemisphere lesion and 40 age-matched neurotypical community-dwelling adults were administered three verbal fluency tasks: two semantic (animals and actions) and one phonemic (the letters F, A and S). Data analysis included comparison of total scores, clusters and perseverations. Individual responses were coded for frequency of occurrence, age of acquisition and syllable length to investigate qualitative differences in word generation.

OUTCOMES & RESULTS

PWA performed worse than neurotypical participants across all verbal fluency tasks, and animal fluency scores were farthest from neurotypical performance. PWAs' animal and action fluency were correlated with other language measures, while phonemic fluency was uncorrelated with language measures. While some PWAs showed dissociations between verbal fluency tasks, the dissociations did not pattern along with aphasia fluency. PWAs produced fewer clusters and responses with higher word frequency across all three verbal fluency tasks. Responses had earlier age of acquisition and shorter word length for animal and phonemic fluency, but not action fluency.

CONCLUSIONS & IMPLICATIONS

Verbal fluency, particularly animal fluency, is sensitive to even mild aphasia. PWA produced lexically simpler responses than their neurotypical peers. This study identifies the relevance of qualitative analysis of verbal fluency responses.

Component analysis of verbal fluency performance in younger participants with moderate-to-severe traumatic brain injury

PRIMARY OBJECTIVE

To investigate phonemic and semantic verbal fluency performance in a group of young adult participants with and without traumatic brain injury.

RESEARCH DESIGN

Group comparison.

METHODS AND PROCEDURES

Twenty-five participants with moderate-to-severe TBI and 25 participants with no brain damage (NBD) were given phonemic and semantic verbal fluency tasks. Responses were analysed quantitatively and qualitatively.

MAIN OUTCOMES AND RESULTS

Young participants with moderate-to-severe TBI generated significantly fewer total correct words and sub-categories for both fluency conditions when compared to controls. The total number of correct words generated on the phonemic condition and for the semantic category of animals was positively correlated with the number of category switches produced during the task.

CONCLUSIONS

While young participants with moderate-to-severe TBI produced fewer total correct words on both verbal fluency conditions in comparison to controls, these differences were greater on the phonemic condition. Participants with moderate-to-severe TBI switched less frequently on both fluency tasks and produced smaller cluster sizes only on the phonemic task in comparison to controls. These results are in contrast with previous investigations that have observed greater age-related declines on semantic tasks when compared to phonemic tasks.

Heterogeneity of letter fluency impairment and executive dysfunction in Parkinson's disease

Letter fluency deficits are commonly detected in non-demented Parkinson's disease (PD) patients but the underlying cause remains uncertain. We investigated the role of slowed processing speed and executive dysfunction. Eighteen nondemented PD participants and nineteen controls were compared on letter fluency using a fluency index (Fi); the average time to "think" of each word, a measure independent of motor speed. Video analyses produced thinking times to switch between word clusters and generate a word within a cluster. Correlational and regression analyses were undertaken with tests of processing speed and executive functioning. The PD group exhibited significantly longer fluency indices than controls across all components. Performance on tests of executive functioning explained a significant proportion of variance whereas performance in processing speed tests did not. Moreover, PD participants with an executive functioning impairment showed significantly worse switching fluency indices only compared with Controls and PD participants without executive dysfunction. PD participants with executive dysfunction exhibited a disproportionate impairment in the time taken to switch between clusters than to think of words within clusters. Executive functioning contributed to fluency performance more than processing speed. Cognitive heterogeneity and motor slowing, may mask the profile of cognitive dysfunction in neurodegenerative disease.

The Abilities Associated with Verbal Fluency Performance in a Young, Healthy Population Are Multifactorial and Differ Across Fluency Variants

Numerous variants of verbal fluency tasks exist within clinical and research domains that purport to measure "executive function." However, to date, there has been a paucity of research examining what specific abilities are measured by these tasks. In this study, the relationships between a select group of cognitive constructs and phonemic, semantic, alternating, and excluded-letter verbal fluency tests were examined in 93 young healthy individuals (aged 18 to 35 years old). Forward-selection multiple regression analyses were performed for each fluency task. Phonemic fluency was associated with verbal intellectual function and processing speed; semantic fluency was associated with working memory and semantic word retrieval; excluded-letter fluency was associated with processing speed; and alternating fluency was associated with semantic word retrieval. These results highlight verbal intellectual function, processing speed, and semantic word-retrieval contributions to verbal fluency performances. The main conclusion from this study is that the abilities associated with verbal fluency performance in a young healthy population are multifactorial and differ across fluency variants. These findings progress our theoretical understanding of what is measured by different verbal fluency tasks and will assist interpretation of performance.

Clinical and cognitive correlates of psychiatric comorbidity in delusional disorder outpatients

OBJECTIVES

The aims of this study were to investigate the prevalence, as well as the clinical, cognitive, and functional correlates of psychiatric comorbidity in patients with delusional disorder (DD).

METHODS

Eighty-six outpatients with DSM-IV DD were evaluated for psychiatric comorbidity on Axis I disorders using the Mini International Neuropsychiatry Interview (MINI). The following instruments were administered: the Standardized Assessment of Personality (SAP), the Positive and Negative Symptom Scale (PANSS), the Montgomery-Asberg Depression Rating Scale (MADRS), a neuropsychological battery (consisting of measures for attention, verbal and working memory, and executive functions), the Sheehan Disability Inventory (SDI), and the Global Assessment of Functioning (GAF) scale. A socio-demographic and clinical questionnaire was also completed.

RESULTS

Forty-six percent of the subjects had at least one additional lifetime psychiatric diagnosis, the most common being depressive disorders (N = 16, 32.6%), followed by anxiety disorders (N = 8, 14%). DD with comorbid Axis I disorders (N = 40, 46.5%) was associated with a specific syndromic constellation (more common cluster C personality psychopathology, somatic delusions, olfactory and gustatory hallucinations, and suicide risk), and greater severity of the psychopathology, particularly as regards emotional dysregulation (total and general PANSS scales, MADRS, and perceived stress SDI scoring). In contrast, DD without psychiatric comorbidity - "pure" DD - (N = 46, 53.5%) was associated with worse overall neurocognitive performance, mainly in working memory. There were no differences in functionality between the two groups (as per the GAF and SDI total, work, social and family life disability scores).

CONCLUSIONS

Our findings reveal one type of DD with associated psychiatric comorbidity with greater emotion-related psychopathology and another "pure" DD, without psychiatric comorbidity, related to worse global cognitive functioning. Treatment for DD should address both types of processes.

Criterion validity of the Delis-Kaplan Executive Function System (D-KEFS) fluency subtests after traumatic brain injury

The performance of 65 patients with complicated mild-severe traumatic brain injury was evaluated on the Verbal and Design Fluency subtests of the Delis-Kaplan Executive Function System (D-KEFS), and compared with that of 65 demographically matched healthy controls. There were statistically significant group differences on Letter Fluency and Category Switching but not on any of the Design Fluency tasks. Combined, these two Verbal Fluency subtests had a classification accuracy of 65.39%, associated with a likelihood ratio of 1.87. The impact of length of coma on Letter Fluency performance but not Category Switching was mediated at least in part by processing speed. The findings suggest modest criterion validity of some of the D-KEFS Verbal Fluency subtests in the assessment of patients with complicated mild-severe traumatic brain injury.

The effect of premorbid demographic factors on the recovery of neurocognitive function in traumatic brain injury patients

OBJECTIVE

Premorbid demographic backgrounds of injured individuals are likely to reflect more accurately the status of patients with traumatic brian injury (TBI) than clinical factors. However, the concrete study about the relationship between the demographic factors and neurocognitive function in TBI patients has not been reported. The object of this study was to evaluate the effect of premorbid demographic factors on the recovery of neurocognitive function following TBI.

METHODS

From July 1998 to February 2007, 293 patients (male: 228, female: 65) with a history of head injury, who had recovered from the acute phase, were selected from our hospital to include in this study. We analyzed the effect of premorbid demographic factors including age, sex, educational level and occupation on the recovery of neurocognitive function in each TBI subgroup as defined by Glasgow Coma Scale (GCS) score. Intelligence and memory are components of neurocognitive function, and the Korean Wechsler Intelligence Scale (K-WAIS) and the Korean memory assessment scale (K-MAS) were used in this study. The results were considered significant at p<0.05.

RESULTS

The higher level of education was a good prognostic factor for intelligence regardless of GCS score and younger age group showed a better result for memory with an exception of severe TBI group. In the severe TBI group, the meaningful effect of demographic factors was not noted by the cause of influence of severe brain injury.

CONCLUSION

The demographic factors used in this study may be helpful for predicting the precise prognosis and developing an appropriate rehabilitation program for TBI patients.