Treatment of verbal short-term memory abilities to improve language function in aphasia: A case series treatment study.

Recent approaches to interventions for aphasia have incorporated verbal short-term memory (STM) and working memory (WM) components. We investigated whether a treatment involving repetition of word sequences after a response delay would improve tolerance of increased verbal STM load in repetition and, consequently, improve performance on repetition and other language tasks. Eight individuals with aphasia participated. We used a single subject design with outcome measures on near-transfer tasks closely related to the treatment task and far-transfer tasks more distantly related to the treatment task. We minimized repeated presentation of stimuli in all phases of treatment to control for confounding effects of repeated exposure of treated items. Four participants demonstrated modest acquisition effects. On outcome measures, we observed improvements by some participants on near-transfer tasks, (repetition of concrete and abstract word strings and verbal spans) and far-transfer tasks (naming and discourse). Some participants demonstrated a significant decline in word repetition accuracy after a response delay before treatment, indicating difficulty in maintaining activation of linguistic representations. It was these participants who showed the most improvement on outcome measures. More studies are needed to determine who will respond to this treatment and what factors might influence the effectiveness of this treatment approach.

Assessment of linguistic and verbal short-term memory components of language abilities in aphasia.

Some current models of aphasia emphasize a role of short-term memory in the processing of language and propose that the language impairment in aphasia involves impairment to cognitive processes that activate and maintain representations of words over the time-period needed to support single word and multiple word tasks, including verbal span tasks. This paper reports normative data from 39 people with aphasia and 16 age-matched neurotypical controls on a test battery for aphasia that assesses effects of increased short-term/working memory load on word and sentence processing as well as effects of linguistic variations on verbal short-term memory abilities Two concepts are discussed that capture the unique potential of this test battery for research and clinical practice: specificity of diagnosis and sensitivity to all degrees of aphasia severity, including mild aphasia. An analysis is included that shows how the performance of individuals with mild aphasia who achieve normal level of performance on the Western Aphasia Battery (Kertesz, 2006) show a decline in a temporal delay condition that is greater than performance of control participants. We also report preliminary data showing differential effects of adding a time interval before a response or between items to be compared: reduced accuracy for some individuals with aphasia and improved accuracy for others. The theoretical and clinical importance of this finding is discussed, as well as the overall potential for this test battery to be used in research and as a clinical tool. Finally, we discuss the relevance of this test battery to investigate functional communication abilities in aphasia.

Short-Term Memory and Aphasia: From Theory to Treatment.

This article reviews existing research on the interactions between verbal short-term memory and language processing impairments in aphasia. Theoretical models of short-term memory are reviewed, starting with a model assuming a separation between short-term memory and language, and progressing to models that view verbal short-term memory as a cognitive requirement of language processing. The review highlights a verbal short-term memory model derived from an interactive activation model of word retrieval. This model holds that verbal short-term memory encompasses the temporary activation of linguistic knowledge (e.g., semantic, lexical, and phonological features) during language production and comprehension tasks. Empirical evidence supporting this model, which views short-term memory in the context of the processes it subserves, is outlined. Studies that use a classic measure of verbal short-term memory (i.e., number of words/digits correctly recalled in immediate serial recall) as well as those that use more intricate measures (e.g., serial position effects in immediate serial recall) are discussed. Treatment research that uses verbal short-term memory tasks in an attempt to improve language processing is then summarized, with a particular focus on word retrieval. A discussion of the limitations of current research and possible future directions concludes the review.

The Link Between Verbal Short-Term Memory and Anomia Treatment Gains.

Purpose A significant relationship between verbal short-term memory (STM) and language performance in people with aphasia has been found across studies. However, very few studies have examined the predictive value of verbal STM in treatment outcomes. This study aims to determine if verbal STM can be used as a predictor of treatment success. Method Retrospective data from 25 people with aphasia in a larger randomized controlled trial of phonomotor treatment were analyzed. Digit and word spans from immediately pretreatment were run in multiple linear regression models to determine whether they predict magnitude of change from pre- to posttreatment and follow-up naming accuracy. Pretreatment, immediately posttreatment, and 3 months posttreatment digit and word span scores were compared to determine if they changed following a novel treatment approach. Results Verbal STM, as measured by digit and word spans, did not predict magnitude of change in naming accuracy from pre- to posttreatment nor from pretreatment to 3 months posttreatment. Furthermore, digit and word spans did not change from pre- to posttreatment or from pretreatment to 3 months posttreatment in the overall analysis. A post hoc analysis revealed that only the less impaired group showed significant changes in word span scores from pretreatment to 3 months posttreatment. Discussion The results suggest that digit and word spans do not predict treatment gains. In a less severe subsample of participants, digit and word span scores can change following phonomotor treatment; however, the overall results suggest that span scores may not change significantly. The implications of these findings are discussed within the broader purview of theoretical and empirical associations between aphasic language and verbal STM processing.

The Influence of Phonomotor Treatment on Word Retrieval: Insights From Naming Errors.

Purpose An increasing number of anomia treatment studies have coupled traditional word retrieval accuracy outcome measures with more fine-grained analysis of word retrieval errors to allow for more comprehensive measurement of treatment-induced changes in word retrieval. The aim of this study was to examine changes in picture naming errors after phonomotor treatment. Method Twenty-eight individuals with aphasia received 60 hr of phonomotor treatment, an intensive, phoneme-based therapy for anomia. Confrontation naming was assessed pretreatment, immediately posttreatment, and 3 months posttreatment for trained and untrained nouns. Responses were scored for accuracy and coded for error type, and error proportions of each error type (e.g., semantic, phonological, omission) were compared: pre- versus posttreatment and pretreatment versus 3 months posttreatment. Results The group of treatment participants improved in whole-word naming accuracy on trained items and maintained their improvement. Treatment effects also generalized to untrained nouns at the maintenance testing phase. Additionally, participants demonstrated a decrease in proportions of omission and description errors on trained items immediately posttreatment. Conclusions Along with generalized improved whole-word naming accuracy, results of the error analysis suggest that a global (i.e., both lexical-semantic and phonological) change in lexical knowledge underlies the observed changes in confrontation naming accuracy following phonomotor treatment.

Links Between Short-Term Memory and Word Retrieval in Aphasia.

Purpose: This study explored the relationship between anomia and verbal short-term memory (STM) in the context of an interactive activation language processing model. Method: Twenty-four individuals with aphasia and reduced STM spans (i.e., impaired immediate serial recall of words) completed a picture-naming task and a word pair repetition task (a measure of verbal STM). Correlations between verbal STM and word retrieval errors made on the picture-naming task were examined. Results: A significant positive correlation between naming accuracy and verbal span length was found. More intricate verbal STM analyses examined the relationship between picture-naming error types (i.e., semantic vs. phonological) and 2 measures of verbal STM: (a) location of errors on the word pair repetition task and (b) imageability and frequency effects on the word pair repetition task. Results indicated that, as phonological word retrieval errors (relative to semantic) increase, bias toward correct repetition of high-imageability words increases. Conclusions: Results suggest that word retrieval and verbal STM tasks likely rely on a partially shared temporary linguistic activation process.

Influence of Linguistic and Nonlinguistic Variables on Generalization and Maintenance Following Phonomotor Treatment for Aphasia.

PURPOSE: Although phonomotor treatment shows promise as an effective intervention for anomia in people with aphasia, responses to this treatment are not consistent across individuals. To better understand this variability, we examined the influence of 5 participant characteristics-age, time postonset, aphasia severity, naming impairment, and error profile-on generalization and maintenance of confrontation naming and discourse abilities following phonomotor treatment. METHOD: Using retrospective data from 26 participants with aphasia who completed a 6-week phonomotor treatment program, we examined the relationships between participant characteristics of interest and change scores on confrontation naming and discourse tasks, measured pretreatment, immediately following treatment, and 3 months following treatment. RESULTS: Although the participant characteristics of aphasia severity and error profile appeared to predict generalization to improved confrontation naming of untrained items and discourse performance, a post hoc analysis revealed that no one characteristic predicted generalization across participants at 3 months posttreatment. CONCLUSIONS: Response to phonomotor treatment does not appear to be influenced by aphasia and anomia severity level, error profile, participant age, or time postonset. Other factors, however, may influence response to intensive aphasia treatment and are worthy of continued exploration.

Language treatment prior to anterior temporal lobe surgery: Can naming skills be preserved?

Epilepsy affects 1% of the general population and is highly prevalent among Veterans. The purpose of this phase I study was to investigate a presurgical linguistically distributed language treatment program that could potentially diminish effects of proper-name retrieval deficits following left anterior temporal lobe resection for intractable epilepsy. A single-subject multiple-baseline design was employed for three individuals with late-onset chronic left temporal lobe epilepsy. Word retrieval treatment was administered prior to anterior temporal lobe resection. The primary outcome measure was confrontation naming of proper nouns. Immediately posttreatment (before surgery), there was a positive effect for all trained stimuli in the form of improved naming as compared with pretreatment. In addition, trained stimuli were found to be better after surgery than they were at pretreatment baseline, which would not be expected had language treatment not been provided. This series of case studies introduces two fundamentally novel concept: that commonly occurring deficits associated with left temporal lobe epilepsy can be treated despite the presence of damaged neural tissue and that providing this treatment prior to surgery can lead to better preservation of language function after surgery than would be expected if the treatment were not provided.

An analysis of aphasic naming errors as an indicator of improved linguistic processing following phonomotor treatment.

PURPOSE: The aim of this study was to investigate the influence of phonomotor treatment on the types of errors produced during a confrontation naming task for people with aphasia (PWA). METHOD: Ten PWA received 60 hr of phonomotor treatment across 6 weeks. Confrontation naming abilities were measured before and after treatment, and responses were coded as correct or incorrect. Incorrect responses were coded for error type. Paired t tests comparing pre-, post- and 3 months posttreatment naming accuracy and error type were performed. RESULTS: Group data showed that naming accuracy on trained items improved significantly immediately post treatment, and gains were maintained 3 months later. Naming accuracy on untrained items did not show significant improvement immediately post treatment or 3 months later. Results of error type analysis were not significant. However, a decrease in omission errors and an increase in mixed errors were noted immediately post treatment for naming of untrained items. CONCLUSION: Results suggest that intensive phonomotor treatment improved lexical-retrieval abilities and may have triggered a shift in linguistic processing, as indicated by a decrease in omission errors on trained items and an increase in mixed errors on untrained items.

Treatment of proper name retrieval deficits in an individual with temporal lobe epilepsy.

PURPOSE: Studies investigating language deficits in individuals with left temporal-lobe epilepsy have consistently demonstrated impairments in proper name retrieval. The aim of this Phase I rehabilitation study was to investigate the effects of a linguistically distributed word retrieval treatment on proper name retrieval in an individual with left temporal-lobe epilepsy. METHOD: A 61-year old right-handed male with left temporal-lobe epilepsy (clinical onset at the age of 50) and a deficit in proper name retrieval participated in this study. A single-subject, repeated-probe ABAA design with testing before, immediately after, and 3 months after treatment completion was employed. Proper name retrieval treatment was administered 2 hr per day for 5 days. RESULTS: Results demonstrated improved naming on trained items and maintenance of trained items 3 months after treatment completion. CONCLUSION: Treatment, which took advantage of the individual's undamaged linguistic networks, promoted the reorganization of networks supporting proper naming, leading to improved proper name retrieval. Further research replicating these findings in individuals with varying degrees of proper name retrieval impairment is warranted. Additionally, the mechanism behind the observed improvements in proper name retrieval needs to be investigated further using functional neuroimaging.