The contribution of working memory to language comprehension: differential effect of aphasia type

Background: Experimental studies of short-term memory and working memory (WM) in aphasia fail to discriminate cognitive impairments of different aphasia types—non-fluent, Broca-type aphasia and fluent, Wernicke-type aphasia. However, based on the varying fundamental features of these two aphasia syndromes, the potentially different underlying mechanisms of impairment and scant preliminary evidence of varying cognitive deficits, a differential relationship between cognitive function and language processing in these two groups can be predicted.

Aims: The current study investigates the hypothesis concerning the differential impact of cognitive impairments in individuals with fluent versus non-fluent aphasia types.

Methods & Procedures: Participants with fluent (n = 19) and non-fluent (n = 16) aphasia and participants without brain damage (n = 36) were presented with an eye-tracking WM task. Additionally, individuals with aphasia completed two language comprehension tasks.

Outcomes & Results: Results revealed significant decrease in WM capacity in individuals with aphasia compared with participants without brain damage. The two aphasia groups performed similarly on the WM and language tasks. Furthermore, for participants with non-fluent aphasia, it was revealed that WM makes a significant contribution to language comprehension, while for fluent individuals this relationship was not significant.

Conclusions: Overall, the present data support the claim that there are cognitive deficits in aphasia and that these cognitive deficits tend to exacerbate the language impairments of persons with non-fluent aphasia types. The results are discussed in the context of varying mechanisms of impairment in different types of aphasia. The present findings have important implications both for the assessment and the treatment of individuals with aphasia and for understanding the nature of aphasia.     

Aphasia type, age and cerebral infarct localisation

Stroke patients with non-fluent aphasia tend to be younger than fluent aphasics. We investigated whether this difference was due to an age-related change in the anatomico-functional organisation of language areas or to an age-dependent variation on the distribution of infarct localisation. From a hospital prospective stroke database we selected those patients who suffered an ischaemic stroke with at least one non-lacunar infarct demonstrated by computed tomography (n = 423 patients). We retrieved information on language disturbance in the acute phase (no aphasia, non-fluent aphasia, fluent aphasia) and on infarct localisation by CT. Non-fluent aphasia predominated in young (aged < 51 years) patients while in elderly patients (aged > 70 years) the opposite was found (χ² = 8.03; P = 0.005). Posterior infarcts were also more frequent in elderly patients (χ² = 9.9; P = 0.002). There were 27 atypical cases (patients with lesions on language areas without aphasia) and 14 aphasics with atypical infarct localisation (9 fluent aphasics with anterior lesions and 5 non-fluent aphasics with posterior lesions). The proportions of atypical cases, their infarct location or fluency type were not influenced by age. It was concluded that the predominance of fluent aphasia in older patients was related to the higher proportion of posterior infarcts in these patients. The hypothesis of age-related changes in the anatomico-functional organisation of language areas was not supported by the present data. Received: 14 January 1997 Received in revised form: 28 April 1997 Accepted: 26 May 1997     

Aphasia in stroke patients: early outcome following thrombolysis

Background: Data on the early course of stroke-related aphasia after thrombolysis are scant.

Aims: The aim of this study was to describe recovery patterns of aphasia after thrombolysis in a large sample of stroke patients.

Methods & Procedures: Clinical and radiological data of consecutive stroke patients treated with thrombolysis over a 5-year period were routinely entered into prospective registries at two stroke units. Recovery was evaluated using the National Institutes of Health Stroke Scale (NIHSS) at baseline, after 24 hr, and on day 7. Aphasia was defined as a score >0 on item 9 of the NIHSS (measurement of language skills), aphasia improvement as any decrease in the item-9 score, and aphasia resolution as an item-9 score of 0. To assess global motor and language impairments, we created a composite language score obtained by summing the scores for items 1b, 1c, and 9; and a composite motor score obtained by summing the scores for items 4, 5, and 6.

Outcomes & Results: Out of the 338 patients treated with thrombolysis, 137 (40.5%) had aphasia. In patients with both aphasia and motor deficits (n = 109), these two impairments showed similar recovery patterns. Aphasia recovered significantly better in patients without limb motor deficits (n = 28) than those with limb motor deficits (n = 109), both after 24 hr (p < 0.05) and after 7 days (p < 0.0001). These results were supported by findings from a group-based trajectory modelling methods (p < 0.005).

Conclusions: Language impairments and limb motor deficits show similar recovery after thrombolysis in a given patient. Aphasia recovery is significantly better in the absence of limb motor deficits.     

Role of cognitive control in language deficits in different types of aphasia

ABSTRACT

Background: Although studies show that different facets of cognitive control are impaired in persons with aphasia (PWA), the question how they impact language abilities in different types of aphasia remains open.

Aims: Following the hypothesis that diminished attention contributes to language impairments in aphasia, we predicted that both fluent and non-fluent PWA would perform worse than neurologically intact individuals on verbal and non-verbal cognitive control tasks. Also, testing the view that linguistic disturbances in fluent and non-fluent PWA dissociate, we predicted differential relationships in performance on cognitive control tasks and language impairment.

Methods & Procedures: Fluent PWA (N = 17) and non-fluent PWA (N = 14) were compared to unimpaired speakers (N = 21) on the non-verbal Flanker task tapping domain-general cognitive control, and Stroop task measuring verbal cognitive control, as well as subtests from the Russian version of the Birmingham Cognitive Screen, namely the Auditory Control task tapping verbal cognitive control and the Rule Finding task measuring domain-general cognitive control. All PWA completed picture naming and language comprehension tasks.

Outcomes & Results: All PWA were more impaired on the Stroop and Auditory Control tasks, with no impairment on the non-verbal Flanker task compared to the controls. Non-fluent PWA also performed significantly worse on the Rule Finding that requires forming and updating non-verbal relational representations. Differences between aphasia groups were found on the Auditory Control task only, where non-fluent PWA were more vulnerable to task demands. Correlation analyses found that verbal and non-verbal cognitive control performance was correlated for the non-fluent group, whereas only correlations between verbal cognitive control tasks were significant for the fluent group. For all PWA, non-verbal cognitive control indexed by Flanker interference scores was related to language comprehension, whereas verbal cognitive control was related to picture naming. However, non-verbal relational reasoning as indexed by the Rule Finding task was significantly related to language comprehension in the non-fluent group only.

Conclusions: All PWA had diminished verbal cognitive control. Non-fluent PWA demonstrated higher vulnerability to domain-general cognitive control deficits compared to fluent PWA. Performance on verbal and non-verbal cognitive control tasks significantly overlapped in the non-fluent group only. Both groups recruited non-verbal cognitive control during language comprehension and verbal cognitive control during picture naming. Only non-fluent PWA relied on domain-general relational reasoning during language comprehension. These findings reinforce the importance of cognitive assessment in aphasia.     

A comparison of two working memory tasks in aphasia

Background: Overall, there is growing consensus that working memory (WM) should be routinely assessed in individuals with aphasia as it can contribute significantly to their level of language impairment and be an important factor in treatment planning. However, there is still no consensus in the field as to which tasks should be used to assess WM in aphasia. The two main alternatives are adapted complex span tasks and N-back tasks. Both have been used interchangeably in previous studies of WM in aphasia, even though the correspondence between the two tasks has not been properly established.

Aims: The current study investigates the relationship between two WM tasks—complex span and N-back tasks—in a large sample of individuals with aphasia. The relationships of these tasks to measures of language comprehension are also explored, as well as differences in performance patterns between individuals with non-fluent and fluent aphasia.

Methods & Resources: Forty-four participants with aphasia (non-fluent: n = 27; fluent: n = 13; mixed: n = 4) were examined with a modified listening span task (Ivanova & Hallowell, 2014), an auditory verbal 2-back task, and a standardised Russian language comprehension test.

Outcomes & Results: Results revealed a moderate relationship between the two WM measures, but demonstrated a divergence in terms of their relationship to language comprehension. Performance on the modified listening span task was related to language comprehension abilities, but performance on the 2-back task was not, suggesting that the two tasks primarily index different underlying cognitive mechanisms. Furthermore, the relationship between the modified listening span task and language comprehension was significant for individuals with non-fluent aphasia, but not for those with fluent aphasia.

Conclusions: Overall, the data demonstrate that while performance of individuals with aphasia was related on the two tasks, the two tasks cannot be substituted for one another without further inquiries into their underlying differences.     

An application of the experience sampling method to the study of aphasia: A case report

Background: Researchers stress that functional health and psychological well-being are important aspects of quality of life in the investigation of individuals with aphasia. Employed in the social sciences, the experience sampling method (ESM) has begun to shed light on deviations in participants' momentary responses to behavioural contingencies in naturalistic environments. Applications of ESM have demonstrated value in monitoring within-participant variations in mood, psychopathology, and treatment outcomes while minimising the effect of memory bias. Additionally, the application of ESM in psychological cognitive-behavioural therapy and occupational therapy (OT) research reportedly appeared to contribute to treatment success. A time-based, fixed-schedule sampling application of ESM was used in this study to attain self-reports throughout an aphasia treatment programme.

Aims: The current investigation introduced the ESM paradigm to the study of aphasia and piloted its use in measuring psychoemotional variables in an individual with chronic aphasia participating in an intensive treatment regime.

Methods & Procedures: Repeated ESM probes were administered during a university-based treatment programme to measure the daily responses of a 75-year-old participant with a moderate-to-severe communicative impairment secondary to a cerebral vascular accident (CVA). A total of 20 brief ESM probes were cued by clinicians at four fixed times per day, 5 days a week during a 35-hour a week, 6-week programme. Probes conducted throughout each day used a 5-point Likert scale to query participant response to psychoemotional variables perceived happiness, perceived tiredness, perceived stress, and perceived communication satisfaction.

Outcomes & Results: Findings revealed that the participant with aphasia was able to respond to a 5-point Likert scale administered with a personal data assistant (PDA) with 100% compliance when cued by clinicians that it was time to complete the ESM probe (464 responses across 29 days). The internal validity of internal states used in this study is supported by the strong negative correlation found with perceived happiness between both perceived tiredness (p < .01) and perceived stress (p < .01), as well as the positive correlation found between the negative states of perceived tiredness and perceived stress (p < .01).

Conclusions: This initial success of ESM implementation in this case study of aphasia treatment suggests that further explorations are needed in the application of ESM in aphasia research.     

The effects of instrumentality and name relation on action naming in Russian speakers with aphasia

Background: A verb’s instrumentality and name relation to an associated instrument noun are among the factors influencing verb retrieval in speakers with aphasia. Previous data on the effects of these factors are equivocal, possibly due to language- and task-specific factors.

Aims: The present study aimed to investigate the nature of the instrumentality and verb-noun name relation effects by retesting them in a large sample of Russian-speaking individuals with fluent and non-fluent aphasia.

Methods & Procedures: Forty Russian-speaking individuals with aphasia (twenty with fluent and twenty with non-fluent aphasia) and twenty controls performed an action naming task. Overall accuracy scores and qualitative error types were analysed.

Outcomes & Results: A positive effect of instrumentality was found in both groups of individuals with aphasia. A negative effect of verb-noun name relation was found in non-fluent aphasia and was larger for verbs with a smaller overlap with the instrument noun. In both aphasia groups, semantically related errors were more numerous for non-instrumental than instrumental verbs, whereas phonological errors were more numerous for name-related than non-name-related instrumental verbs.

Conclusions: The positive effect of instrumentality on verb retrieval may be attributed to a facilitatory effect of richer conceptual representations of instrumental verbs. The negative effect of name relation on verb retrieval may be explained by interference of the phonological form of the instrument noun. These factors influence verb retrieval in aphasia and should be taken into account when developing testing/treatment materials and stimuli for experimental studies.     

Constraint induced language therapy in early aphasia rehabilitation

Background: Constraint induced language therapy (CILT) focuses on improving acquired expressive language deficits after stroke by applying intensive, use-dependent treatment with constraint to spoken verbal expression. Most CILT research has utilised individuals with chronic aphasia, and previous results indicated improvement on the language assessments after intervention that was largely retained at follow-up.

Aims: The purpose of this study was to explore the applicability and outcome of a programme of CILT in individuals in the early phase of recovery from aphasia (1–2 months post onset) in an inpatient rehabilitation hospital setting.

Methods & Procedures: A 10-day/3 hours a day pre–posttest CILT intervention case series was carried out 1–2 months post onset with three Norwegian rehabilitation inpatients with aphasia following left CVA. Procedures involved card activities using high- and low-frequency picture stimuli with communicative relevance at four levels of complexity, either in a small group or one-to-one with a trained SLP.

Outcomes & Results: Results suggested an overall improvement on the language assessments post CILT intervention, as well as at the follow-up. A greater degree of improvement in performance on expressive speech tasks compared to receptive and written tasks suggested a treatment-specific effect of CILT for early aphasia rehabilitation. Participant evaluation of the CILT intervention reflected positive feedback for the treatment experience and satisfaction with individual gains. Challenges in the application of CILT to this phase of recovery were the need to accommodate the demands of the inpatient rehabilitation setting and the decreased stamina of the participants.

Conclusions: The results of this study support the applicability of CILT in early aphasia rehabilitation, with some modifications of the original protocol.     

Effect of High Frequency Transcranial Magnetic Stimulation on Recovery of Chronic Post-Stroke Aphasia

BackgroundBoth hemispheres have role in post-stroke aphasia recovery but better recovery is expected with the restoration of function by the left hemisphere. Transcranial stimulation has been used to favor recruitment of left-hemispheric language networks and increase activity of the left hemisphere, thus helps aphasia recovery. ObjectiveThe aim of this study is to evaluate the effect of excitatory repetitive transcranial magnetic stimulation (rTMS) on recovery of post stroke aphasic patients. Materials and methodsTwenty patients with post stroke chronic aphasia were enrolled in the study. Aphasia severity was assessed using Aphasia Severity Rating Scale (ASRS). Linguistic deficits were assessed using Kasr Al-Aini Arabic Aphasia test (KAAT). Real rTMS was applied three for 10 sessions of 10-Hz stimulation, positioned over the left Broca's area of the affected hemisphere. All patients were evaluated before, after the end of treatment sessions and one month later. ResultsThere was a significant improvement in the mean total score and mean scores of components of KAAT scale before, immediately after and after one month of rTMS (P< 0.05). Moreover, there was a significant improvement in mean scores of ASRS before, immediately after and after one month of rTMS (P= 0.000). There was a significant difference in mean scores of ASRS and KAAT before, immediately after the last session and after one month between small, medium and large brain infarcts. (P< 0.05).ConclusionExcitatory rTMS is a beneficial adjuvant therapy that improves language skills in patients with chronic post-stroke non-fluent aphasia in short and long term.The protocol of this observational study was registered in clinical trial registration: www.ClinicalTrials.gov, identifier: NCT04708197     

Spontaneous evolution of aphasia after ischaemic stroke

Abstract

The relatively few studies concerning spontaneous recovery from aphasia yield contradictory findings because of the large number of influencing factors. We have assessed a selected sample of 45 patients, none of whom received language therapy, in order to determine such patients' chances of spontaneous recovery in relation to type and severity of aphasia and size of lesion. Our results show comprehension to have the best recovery, independent of type and severity of aphasia. Expression shows a lower recovery, especially for non-fluent aphasics; their performance is also negatively influenced by oral apraxia. In addition, the overall severity of aphasia, associated with large lesions, is a negative prognostic factor for recovery of expression.     

Aphasia in patients after brain tumour resection

Background: It is has been estimated that aphasia occurs in one‐third to half of patients who have had a left hemisphere brain tumour resection. While studies have documented aphasia before malignant brain tumour resection, little is known about the type and severity of aphasia after tumour resection.

Aims: The aims of this study were (1) to describe the subtypes and severity of aphasia during the acute recovery period after malignant brain tumour resection; (2) to describe potential associations between acute language outcomes and tumour characteristics; and (3) to compare our findings to those reported in the literature to identify possible language differences between patients who suffer stroke and patients who undergo brain tumour resection.

Methods & Procedures: We retrospectively reviewed the Western Aphasia Battery (WAB) scores during the acute recovery period of individuals who underwent resection of malignant brain tumours to determine patterns of aphasia severity and subtype.

Outcomes & Results: We found that aphasia was usually mild (63% of patients) and that anomic aphasia was the most common subtype (48% of patients) during the acute recovery period after brain tumour resection, regardless of lesion location or tumour grade.

Conclusions: The patterns of postoperative language functioning that we observed during the acute recovery period after surgery for a brain tumour support the perspective that acute aphasia profiles may be fundamentally different in patients with brain tumours compared with patients who have had a stroke.     

Age and aphasia: a review of presence,type, recovery and clinical outcomes

Background: Each year approximately 100,000 stroke survivors are diagnosed with aphasia. Although stroke is associated with age, the relationship between age and aphasia is less clear.

Objectives: To complete a review of the literature to examine the relationship between age and: (a) presence or likelihood of aphasia after stroke, (b) aphasia type, (c) aphasia recovery patterns, and (d) aphasia clinical outcomes.

Data Sources: Articles were identified by a comprehensive search of “OneSearch,” PubMed, and individual journals: Aphasiology, Stroke and the Journal of Stroke and Cerebrovascular Diseases.

Study Selection: Inclusion criteria included: age and incidence of aphasia, likelihood of aphasia, aphasia recovery, and aphasia clinical outcome.

Data Extraction: Independent searches were completed by the authors. Each author independently assessed the full text of reports meeting inclusion criteria. Differences regarding study eligibility and need to proceed with data extraction were resolved by consensus.

Results: 1617 articles were identified during the initial search. Forty studies including 14,795 study participants were included in the review. The review generally demonstrated that: (a) stroke patients with aphasia are typically older than stroke with patients without aphasia and (b) aphasia type and age are associated as younger patients with aphasia are more likely to exhibit non-fluent or Broca’s type of aphasia. In contrast, studies examining aphasia recovery and aphasia clinical outcomes did not demonstrate a positive relationship between age and recovery or clinical outcomes.

Conclusions: Stroke is a condition of the elderly. However, age appears to only influence likelihood of aphasia and aphasia type.     

Dynamic-intentional thalamic aphasia: a failure of lexical-semantic self-activation

Background: Previous research has described patients with aphasia from thalamic lesions, some of whom were non-fluent with intact comprehension, others who were fluent with impaired comprehension, and some of whom are non-fluent with impaired comprehension. Whereas these three subtypes usually have normal repetition, they had impaired naming, suggesting a deficit in lexical (phonological word forms)-semantic processing. We report a patient with a left thalamic hemorrhage in which lexical-semantic representations appear to be intact but the patient demonstrates an inability to spontaneously activate his lexical-semantic system Methods: A 82-year-old, right-handed man presented with decreased verbal fluency and memory loss following a thalamic hemorrhage. Neuropsychological assessment revealed significant decrements in verbal fluency with intact naming, comprehension, repetition and vocabulary. Conclusions: To the best of our knowledge this pattern of language disturbance, which mirrors dynamic aphasia induced by frontal lesions, has not previously been described with thalamic injury. The thalamus has strong connections with the frontal lobe and rather than degradation of lexical-semantic representations, this patient's thalamic lesion probably induced frontal lobe dysfunction with a failure to spontaneously active lexical semantic representations.     

Comparing connected language elicitation procedures in persons with aphasia: Concurrent validation of the Story Retell Procedure

Background: Melodic Intonation Therapy (MIT) is a therapeutic approach used to increase verbal output in adults with aphasia through combination of melodic intoning and rhythmic tapping with simple phrase production. Although MIT was developed in the 1970s, few studies have been conducted relative to determining the programme's overall effectiveness as well as examining ability to generalise skills to other communicative contexts.

Aims: The purpose of the current investigation was to examine the effectiveness of MIT as a means of increasing verbal output in a gentleman with chronic Broca's aphasia.

Methods &; Procedures: A modified version of MIT without the tapping component was implemented with BR, 69-year-old male with chronic Broca's aphasia of 4 years' duration. BR had tried MIT previously with little success: he had difficulty with the tapping element and the packaged phrases lacked functionality, adversely affecting his motivation. A set of automatic and self-generated phrases were developed and implemented with a multiple baseline design across phrase type with an established criterion of 75% accuracy over two consecutive sessions for both stimulus sets. Generalisation stimuli were presented at the last weekly session. BR attended three hour-long weekly sessions, for 8 weeks. Follow-up probing with all stimuli occurred at 2 and 4 weeks post-treatment. A set of standardised tests and social validation measures were administered pre- and post-treatment.

Outcomes &; Results: BR reached 75% accuracy on automatic phrases at 4 weeks into the treatment programme, which was retained throughout the maintenance phase and both follow-up sessions. Performance on self-generated phrases was 55% at 8 weeks -post-treatment, which was maintained at both follow-up sessions. Separate Welch two s-ample t-tests used to analyse the automatic and self-generated phrase data, yielded highly significant treatment effects for both data sets, with non-significant findings for autocorrelation. Improved performance on standardised tests was observed most no-tably for auditory comprehension and reading and writing skills, with some improvement in spontaneous speech and naming. Increased perception of communicative effectiveness was reported independently by both BR and his spouse.

Conclusions: Overall, BR significantly increased his ability to produce short phrases using MIT without tapping. Thus MIT appears to be a viable option for enhancing verbal output for some individuals with non-fluent aphasia, regardless of time post-stroke. Additional investigations are needed to examine generalisation effects to other linguistic contexts. Efficiency issues (treatment length, intensity) require further exploration relative to MIT efficacy and effectiveness and its variations.     

Pattern of recovery of oral and written expression and comprehension in aphasic patients

Three hundred and eighty-eight aphasic patients (250 rehabilitated and 138 non-rehabilitated) were subjected to a study whose aim was to analyze the relationship between recovery in 4 specific language skills: oral and written expression and comprehension. By means of Cohen's K coefficient of agreement we sought to ascertain whether recovery of one out of these language skills significantly affected recovery of the remaining 3 language modalities. In rehabilitated patients recovery of oral and written comprehension and expression always turned out to be linked; in non-rehabilitated patients oral comprehension recovery was not associated with recovery of oral expression, reading and writing. Regarding the evolution of aphasia type, none of the experimental subjects changed from a fluent to a non-fluent form of aphasia.