Memory dysfunction in mild aphasics

The effects of adding attention training to naming treatment for individuals with aphasia

AIM

Given the ever-increasing evidence for the co-occurrence of attention impairments and language disorders in chronic aphasia, this study aimed to compare the effects of two naming treatment programs, one with and one without attention training components, on the naming performance of participants with aphasia.

MATERIALS AND METHODS

This was a single-subject crossover study in which six people with chronic aphasia and different degrees of naming and attention impairments participated. Two treatment programs were implemented for each participant, with the sequence of the treatments with crossover design. Each program consisted of 12 treatment sessions plus pre- and post-treatment assessment sessions (15 weeks for each participant). The visual analysis and WEighted STatistics methods were employed for data analysis.

RESULTS

Based on visual analysis, both treatments improved in comparison to the baseline phase. Statistical analysis revealed that the number of participants with significant naming improvement following combined program (5 participants) was larger than the number of participants showing improvement following completion of the single, program.

CONCLUSION

Although integrating attention training into a conventional treatment for anomia can increase the effect of treatment on naming ability, more studies are required to clarify the role of attention in remediating naming impairments in aphasia.

Aphasia associated with non-traumatic subarachnoid haemorrhage: a systematic review

PURPOSE

Individuals with non-traumatic subarachnoid haemorrhage (SAH) are often excluded from studies of stroke populations due to differing pathophysiology and treatment pathways. Thus, aphasia presentation in the non-traumatic SAH population is potentially under-represented within existing research evidence.

MATERIALS AND METHODS

Five databases were systematically searched with terms related to "aphasia" and "subarachnoid haemorrhage." Studies were included if aphasia was attributed to non-traumatic SAH or its associated complications, and where at least one language assessment measure used determined the presence or absence of aphasia. Study quality was evaluated using the Mixed Methods Appraisal Tool (MMAT).

RESULTS

Following deduplication, 2726 articles were identified for title and abstract screening. Full text screening for 162 articles occurred, with 18 articles selected for inclusion. Aphasia incidence ranged from 5 to 24%, and was influenced by assessment measure, timing of assessment, subgroup studied, and classifications of aphasia. Many studies excluded participants with poorer clinical outcome, intracerebral complications, or severe aphasia. Few studies used comprehensive language assessment measures to examine across language domains.

CONCLUSIONS

Aphasia presentation is highly heterogenous following non-traumatic SAH. Future research using comprehensive language assessments at multiple time points post onset is required to better understand aphasia presentation and management needs for this population.

The impact of subcortical stroke-related aphasia on executive functions and working memory

Aphasia is a common post-stroke disorder characterized by impairments in speaking, listening, reading, and writing. Although cognitive impairments have been well studied in cortical aphasia, deficits associated with subcortical aphasia remain to be elucidated. The current study aimed to assess executive functions (EF) and working memory (WM) in patients with subcortical aphasia, and investigate the relationship between language abilities and cognition deficits. Participants of this research included patients with thalamus lesions (n = 9; mean age = 53.89 years) and healthy individuals (n = 9; mean age = 54.33 years). Assessment materials were the Mini-Mental State Examination (MMSE), Persian Western Aphasia Battery (P-WAB-1), digit span subtest of Adult Wechsler Test (WAIS-R), and Wisconsin Card Sorting Test (WCST). Obtained results revealed significant differences in all components of EF, as well as in WM forward and backward digit spans between patients and healthy individuals. However, investigating the relationship between MMSE and AQ scores and components of EF and WM revealed no significant difference. In conclusion, the findings of the present research indicated defects in cognitive functions, including WM and EF, in patients with subcortical stroke. Accordingly, it is crucial to provide optimal rehabilitation therapies for the improvement of language and cognitive problems upon subcortical aphasia.

Temporal and Episodic Analyses of the Story of Cinderella in Latent Aphasia

Purpose The purpose of this study was to improve our understanding of the language characteristics of people with latent aphasia using measures that examined temporal (i.e., real-time) and episodic organization of discourse production. Method Thirty AphasiaBank participants were included (10 people with latent aphasia, 10 people with anomic aphasia, and 10 neurotypical control participants). Speech material of Cinderella narratives was analyzed with Praat software. We devised a protocol that coded the presence and duration of all speech segments, dysfluencies such as silent and filled pauses, and other speech behaviors. Using these durations, we generated a range of temporal measures such as speech, articulation, and pure word rates. Narratives were also coded into episodes, which provided information about the discourse macrostructure abilities of the participants. Results The latent aphasia group differed from controls in number of words produced, silent pause duration, and speech rate, but not articulation rate or pure word rate. Episodic organization of the narratives was similar in these 2 groups. The latent and anomic aphasia groups were similar in most measures, apart from articulation rate, which was lower in the anomic group. The anomic aphasia group also omitted more episodes than the latent aphasia group. Conclusions The differences between latent aphasia and neurotypical controls can be attributed to a processing speed deficit. We propose that this deficit results in an impaired ability to process information from multiple cognitive domains simultaneously.

Systematic review of subjective memory measures to inform assessing memory limitations after stroke and stroke-related aphasia

AIM

Primary aims of this systematic review were to: (1) identify the range of subjective memory measures used in the stroke and stroke-related aphasia literature and (2) critically appraise their psychometric properties as well as (3) the methodological qualities of studies that included them, (4) investigate whether such measures provide an accurate reflection of memory impairments (i.e., in comparison to norms from age-matched, neurotypical participants), (5) document the representation of individuals with stroke-related aphasia, and (6) examine the extent to which subjective memory measures correlate with objective memory measures.

METHODS

Systematic review of the literature from 1970 to June 2019 using a comprehensive range of relevant search terms in EMBASE, Medline, PsychINFO, SCOPUS, and Web of Science. Eligibility criteria were for studies to include adults who had suffered of clinical stroke, to report a subjective memory measure that was completed by the stroke survivors, to be reported in a peer-reviewed journal, and to be published in English or Dutch. Quality appraisal was carried out for the included studies as well as the subjective memory measures they employed.

RESULTS

A total of 7,077 titles or abstracts were screened, with 41 studies included in the quantitative and qualitative synthesis. Twenty-six subjective memory measures were used in the included studies. The critical appraisal of their psychometric properties and the methodological quality of the included studies revealed significant shortcomings; for example, neurotypical participants were included in only 14 of the 41 studies. When statistical comparisons were made, different outcomes arose. Only eight studies statistically compared subjective with objective memory measures.

CONCLUSIONS

This literature domain currently provides an unclear picture as to how memory limitations affect participation in stroke and stroke-related aphasia.IMPLICATIONS FOR REHABILITATIONA broad range of subjective memory measures have been used to determine stroke survivors' perceptions of their everyday memory issues.Because of psychometric weaknesses such as inadequate reliability and cross-cultural validity among subjective memory measures, there remains a need to carefully review a given measure's properties to determine if it is appropriate for use with a given stroke survivor.Stroke survivors with aphasia have been infrequently included or inadequately described in studies of subjective memory measures, and thus how these individuals perceive their everyday memory abilities requires further investigation.Although the relationship between subjective and objective memory measures has been infrequently investigated by stroke researchers, both types of measures should be considered as they likely offer complementary rather than redundant information about stroke survivors' memory abilities.

Psychophysiological Analysis of the Influence of Vasopressin on Speech in Patients with Post-Stroke Aphasias

Speech is an attribute of the human species. Central speech disorders following stroke are unique models for the investigation of the organization of speech. Achievements in neurobiology suggest that there are possible neuroendocrine mechanisms involved in the organization of speech. It is known that the neuropeptide vasotocin, analogous of vasopressin in mammals, modulates various components of vocalization in animals. Furthermore, the positive influence of vasopressin on memory, which plays an important role in the formation of speech, has been described. In this study, speech organization processes and their recovery with the administration of vasopressin (1-desamino-8-D-arginin-vasopressin) to 26 patients with chronic aphasias after stroke were investigated. Results showed that sub-endocrine doses of the neuropeptide with intranasal administration had positive influence primarily on simple forms of speech and secondarily on composite forms. There were no statistically significant differences between the sensory and integrative components of the organization of speech processes with vasopressin. In all cases, the positive effect of the neuropeptide was demonstrated. As a result of the effects, speech regulated by both brain hemispheres improved. It is suggested that the neuropeptide optimizes the activity both in the left and right hemispheres, with primary influence on the right hemisphere. The persistence of the acquired effects is explained by an induction of compensatory processes resulting in the reorganization of the intra-central connections by vasopressin.

Conceptualizing and Measuring Working Memory and its Relationship to Aphasia

BACKGROUND: General agreement exists in the literature that individuals with aphasia can exhibit a working memory deficit that contributes to their language processing impairments. Though conceptualized within different working memory frameworks, researchers have suggested that individuals with aphasia have limited working memory capacity, impaired attention-control processes as well as impaired inhibitory mechanisms. However, across studies investigating working memory ability in individuals with aphasia, different measures have been used to quantify their working memory ability and identify the relationship between working memory and language performance. AIMS: The primary objectives of this article are to (1) review current working memory theoretical frameworks, (2) review tasks used to measure working memory, and (3) discuss findings from studies that have investigated working memory as they relate to language processing in aphasia. MAIN CONTRIBUTION: Though findings have been consistent across studies investigating working memory ability in individuals with aphasia, discussion of how working memory is conceptualized and defined is often missing, as is discussion of results within a theoretical framework. This is critical, as working memory is conceptualized differently across the different theoretical frameworks. They differ in explaining what limits capacity and the source of individual differences as well as how information is encoded, maintained, and retrieved. When test methods are considered within a theoretical framework, specific hypotheses can be tested and stronger conclusions that are less susceptible to different interpretations can be made. CONCLUSIONS: Working memory ability has been investigated in numerous studies with individuals with aphasia. To better understand the underlying cognitive constructs that contribute to the language deficits exhibited by individuals with aphasia, future investigations should operationally define the cognitive constructs of interest and discuss findings within theoretical frameworks.

Performance of Individuals with Left-Hemisphere Stroke and Aphasia and Individuals with Right Brain Damage on Forward and Backward Digit Span Tasks

BACKGROUND: Working memory (WM) limitations have been suggested as a significant source of the linguistic processing deficits observed in individuals with aphasia (IWA). Digits forward (DF) and digits backward (DB) span tasks are frequently used to study WM in both healthy and clinical populations. Unfortunately, only a handful of studies have explored digit span in IWA. AIMS: The purpose of the current study is to measure the DF and DB spans of IWA and compare their digit spans to a group with right brain damage, but no aphasia (RBD). Additionally, DF and DB span is compared within each group to determine if there is indeed a performance differential that may support the idea that DB is a more difficult WM task in these populations. METHODS AND PROCEDURES: Seventeen IWA and 14 individuals with RBD participated in a DF and DB span task. Modifications to the span tasks were implemented to accommodate language deficits. A series of two digits were orally presented to each participant continuing to a maximum of eight digits. There were seven trials per digit series. Participants were asked to point to the correct order of digits on a written 1-9 digit list provided on individual note cards or verbally repeat the numbers if the participant was able to do so. OUTCOMES AND RESULTS: IWA demonstrated shorter digit spans than the RBD group. Both groups performed worse on the DB span tasks than the DF span tasks. CONCLUSIONS: The results are consistent with previous studies suggesting that DB span is shorter than DF span in other populations and that there are differences in performance on digit span tasks between the two groups. The differences between RBD group and IWA may be explained by decreased attentional capacity or inefficient resource allocation in IWA, or alternatively, a deficient phonological loop. Future studies should explore these possibilities.

Assessment of Story Comprehension Deficits After Brain Damage

A story comprehension task was specifically developed for the clinical diagnosis of text comprehension deficits. The performance of 49 healthy control participants on qualitatively different Yes/No questions confirmed that both salience and explicitness of information had an impact on question difficulty. An unselected group of brain damaged patients (n = 96) made more errors, particularly on questions about implicit information. The subgroup of patients with left-hemispheric vascular aetiology (n = 18) had particular difficulties with stated details, patients with right-hemispheric vascular aetiology (n = 12) with implicit main ideas, and patients with traumatic brain injury (n = 34) were most impaired on implicit information. Correlations with neuropsychological test scores also confirmed that the questions successfully tapped different subprocesses of comprehension. Performance on implicit main ideas was correlated with tests of executive functions, whereas the performance on the other three question types was correlated with long-term memory and verbal learning. These results suggest that the story comprehension test is a useful diagnostic tool for neuropsychological assessment.

Working memory in aphasia: theory, measures, and clinical implications

Recently, researchers have suggested that deficits in working memory capacity contribute to language-processing difficulties observed in individuals with aphasia (e.g., I. Caspari, S. Parkinson, L. LaPointe, & R. Katz, 1998; R. A. Downey et al., 2004; N. Friedmann & A. Gvion, 2003; H. H. Wright, M. Newhoff, R. Downey, & S. Austermann, 2003). A theoretical framework of working memory can aid in our understanding of a disrupted system (e.g., after stroke) and how this relates to language comprehension and production. Additionally, understanding the theoretical basis of working memory is important for the measurement and treatment of working memory. The literature indicates that future investigations of measurement and treatment of working memory are warranted in order to determine the role of working memory in language processing.