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.     

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.     

Perseverative behaviour in fluent and non-fluent aphasic adults

Abstract

Perseveration by type (recurrent, continuous, or stuck-in-set) was examined for 30 stroke patients, 20 of whom exhibited fluent aphasia, and 10 with non-fluent aphasia. Comparisons were made between the two aphasic subject groups on two verbal and two non-verbal tasks. Twenty-eight of the patients (93%) produced at least one instance of perseveration. The most commonly occurring type was recurrent perseveration. Instances of continuous perseveration also were common and were produced by 18 patients. Stuck-in-set perseveration was uncommon with only two patients exhibiting this form of perseveration. No differences were observed in the frequency of perseveration across the four tasks between fluent and non-fluent aphasic patients. Perseveration was significantly correlated with aphasia severity, but not with time post-onset.     

Primary progressive dynamic aphasia and Parkinsonism: Generation,selection and sequencing deficits

MC is the first reported case of dynamic aphasia in the context of non-fluent progressive aphasia and Parkinson's disease. MC's language profile was characterised by the hallmark propositional language impairment despite well-preserved naming, reading, repetition and comprehension skills. The severity of MC's propositional language deficit was comparable to other dynamic aphasic patients. Word and sentence generation performance was severely impaired only when many competing responses were activated by a stimulus. Thus, when a dominant response was available verbal generation was satisfactory. MC also presented with a deficit in idea generation and fluent sequencing of novel thoughts as discourse generation was extremely reduced and perseverative. In addition, non-verbal generation was impaired although dissociations emerged. MC was able to generate novel designs and gestures but his performance was highly perseverative, and his motor movement selection was abnormal, resembling a non-random pattern. MC is the first dynamic aphasic case with concurrent deficits in three mechanisms thought crucial for conceptual preparation processes; namely impaired selection, impaired generation of ideas and impaired fluent sequencing of novel thoughts. The findings are discussed in relation to conceptual preparation processes and their organisation, accounts of dynamic aphasia and the roles of the left inferior frontal and basal ganglia regions in conceptual preparation processes for verbal and non-verbal generation.     

Investigating comprehension of nouns and verbs: is there a difference?

Background: There is growing evidence that verbs are often more difficult to process than nouns and that verb retrieval is more commonly affected in aphasia. However, existing observations are largely based on naming and semantic judgment tasks. The extent to which this processing difficulty is modality-general has yet to be established. In addition, most of the present language batteries do not allow direct comparison between noun and verb comprehension deficits. To fill this gap, a test was developed for the assessment of noun and verb lexical-semantic comprehension.

Aims: The current study investigates whether verb processing difficulties are modality-general by administering novel balanced noun and verb comprehension tasks to participants with and without aphasia.

Methods & Procedures: In this study, we directly compare the difficulty of comprehension of verbs versus nouns in a group of participants with aphasia (PWA, n = 32) and non-brain-damaged, age-matched participants (NBD, n = 20). The word comprehension task was implemented on a tablet measuring accuracy and reaction times (RTs). Participants were required to listen to an aurally presented word and match it to one of four pictures (a target and three distractors: semantic, phonological, and irrelevant) by tapping on it with the non-dominant hand. In total, 30 nouns and 30 verbs were presented. The verbal stimuli in the two tasks were matched on relevant psychometric properties such as familiarity, age of acquisition, subjective visual complexity, imageability, image agreement, and frequency.

Outcomes & Results: Both groups experienced more difficulties in the verb comprehension task, indicated by lower accuracy and longer RTs in PWA and longer RTs in NBD. PWA who were performing the task within normal limits (i.e., demonstrated no difference in accuracy compared to the control group) still showed significantly longer RTs in the verb task than controls. Also, PWA who demonstrated similar accuracy in both tasks had longer RTs in the verb task relative to the noun task. The pattern was general and no differences were observed in performance between participants with fluent and non-fluent aphasia types. Moreover, the observed dissociations in RTs were greater for PWA than for NBD, indicating that a damaged language system experiences even more difficulties in processing verbs.

Conclusions: Overall, the study demonstrated the relative difficulty of verb processing in a comprehension task, supporting the hypothesis that verb processing difficulties are modality-general. The new test allows researchers to compare performance on noun and verb comprehension and registers even subtle differences by measuring RTs.     

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     

Cognitive grammar and aphasic discourse

In cognitive grammar (CG), there is no clear division between language and other cognitive processes; all linguistic form is conceptually meaningful. In this pilot study, a CG approach was applied to investigate whether people with aphasia (PWA) have cognitive linguistic difficulty not predicted from traditional, componential models of aphasia. Narrative samples from 22 PWA (6 fluent, 16 non-fluent) were compared with samples from 10 participants without aphasia. Between-group differences were tested statistically. PWA had significant difficulty with temporal sequencing, suggesting problems that are not uniquely linguistic. For some, these problems were doubly dissociated with naming, used as a general measure of severity, which indicates that cognitive linguistic difficulties are not linked with more widespread brain damage. Further investigation may lead to a richer account of aphasia in line with contemporary linguistics and cognitive science approaches.     

What happens when they think they are right? Error awareness analysis of sentence comprehension deficits in aphasia

Background: Comprehension of non-canonical sentences is frequently characterised by chance level performance in people with aphasia (PWA). Chance level performance has been interpreted as guessing, but online data does not support this rendering. It is still not clear whether the incorrect sentence processing is guided by the compensatory strategies that PWA might employ to overcome linguistic difficulties.

Aims: We aim to study to what extent people with non-fluent aphasia are aware of their sentence comprehension deficits.

Methods & Procedures: This study combined offline and online data to investigate the effect of word order and error-awareness on sentence comprehension in a group of PWA and non-brain damaged (NBD) participants. The offline tasks involved auditory sentence picture-matching immediately followed by a confidence rating (CR). Participants were asked to judge the perceived correctness of their previous answer. Online data consisted of eye-tracking.

Outcomes & Results: Replicating previous findings, PWA had significantly worse comprehension of Theme-Agent order compared to Agent-Theme order sentences. Controls showed ceiling level sentence comprehension. CR was a poor predictor of response accuracy in PWA, but moderate-good in NBD. A total of 6.8% of judgements were classified as “guessing” by PWA. Post hoc gaze data analysis indicated that CR was a predictor of the fixation pattern during the presentation of the linguistic stimuli.

Conclusions: Results suggest that PWA were mostly unaware of their sentence comprehension errors and did not consciously employ strategies to compensate for their difficulties.     

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.     

Non-verbal semantic impairment in semantic dementia

The clinical presentation of patients with semantic dementia is dominated by anomia and poor verbal comprehension. Although a number of researchers have argued that these patients have impaired comprehension of non-verbal as well as verbal stimuli, the evidence for semantic deterioration is mainly derived from tasks that include some form of verbal input or output. Few studies have investigated semantic impairment using entirely non-verbal assessments and the few exceptions have been based on results from single cases ([3]: Breedin SD, Saffran EM, Coslett HB. Reversal of the concreteness effect in a patient with semantic dementia. Cognitive Neuropsychology 1994;11:617-660, [12]: Graham KS, Becker JT, Patterson K, Hodges JR. Lost for words: a case of primary progressive aphasia? In: Parkin A, editor. Case studies in the neuropsychology of memory, East Sussex: Lawrence Erlbaum, 1997. pp. 83-110, [21]: Lambon Ralph MA, Howard D. Gogi aphasia or semantic dementia? Simulating and assessing poor verbal comprehension in a case of progressive fluent aphasia. Cognitive Neuropsychology, (in-press). This study employed sound recognition and semantic association tasks to investigate the nature of the verbal and non-verbal comprehension deficit in 10 patients with semantic dementia. The patients were impaired on both verbal and non-verbal conditions of the assessments, and their accuracy on these tasks was directly related to their scores on a range of other tests requiring access to semantic memory. Further analyses revealed that performance was graded by concept and sound familiarity and, in addition, identified significant item consistency across the different conditions of the tasks. These results support the notion that the patients' deficits across all modalities were due to degradation within a single, central network of conceptual knowledge. There were also reliable differences between conditions. The sound-picture matching task proved to be more sensitive to semantic impairment than the word-picture matching equivalent, and the patients performed significantly better on the picture than word version of a semantic association test. We propose that these differences arise directly from the nature of the mapping between input modality and semantic memory. Words and sounds have an arbitrary relationship with meaning while pictures benefit from a degree of systematicity with conceptual knowledge about the object.     

Design fluency subsequent to onset of aphasia: a distinct pattern of executive function difficulties?

ABSTRACT

Background: Executive function problems commonly co-occur with aphasia and influence language and communication performance as well as aphasia treatment outcomes and prognosis. Prior research, however, has focused on a restricted set of executive skills.

Aims: This study examined further the integrity of executive functioning and its relationship to language performance in individuals with aphasia by utilising a design fluency measure, which assesses executive skills like initiation, planning, and cognitive flexibility. To examine domain-general versus domain-specific executive problems and determine the distinctiveness of the aphasic group’s performance pattern, adults with right hemisphere brain damage (RHD) were included. The hypotheses examined were: (a) compared to adults with no brain damage, the aphasic and RHD groups would display design fluency impairments; (b) the design fluency performances of aphasic and RHD groups would be quantitatively but not qualitatively similar; and (c) the design fluency performances of the aphasic and RHD groups would be related to their language abilities, as well as their performance of other executive and cognitive measures.

Methods and Procedures: Participants with aphasia, RHD, or no brain damage completed the Ruff Figural Fluency Test (RFFT; Ruff, 1996), the results of which were quantitatively (i.e., number of unique designs, a perseverative error ratio) and qualitatively analysed (i.e., number and maximum length of orderly patterns, design complexity, number, and types of non-repetition errors), along with a formal cognitive-linguistic test battery and a verbal fluency task.

Outcomes and Results: The traditional, quantitative RFFT scores of the aphasia, and RHD groups were significantly lower than those of the control group. Only the RHD group significantly differed from the control group when qualitative RFFT variables were analysed. RFFT performances correlated with language and other cognitive test scores, with some differences in the number and nature of these associations across the aphasic and RHD groups.

Conclusions: The current design fluency findings indicated that executive function deficits involving initiation, planning, self-monitoring, and cognitive flexibility commonly co-occur with aphasia. These results supported previous research by identifying executive function impairments in many, however, not all individuals with aphasia, and by confirming influential associations between executive function and language, and communication measures. Inclusion of individuals with RHD indicated that such executive function difficulties and a potent relationship between executive functioning and language skills are not only unique to those with aphasia but also prevalent in other patient populations and consistent with the contribution of domain-general factors in acquired cognitive impairments.     

Aphasia assessment and therapy using hypertext-related tasks

Abstract

This paper discusses the potential usefulness of hypertext tools in communication disorders, particularly in aphasia assessment and therapy. The assessment of language comprehension abilities can be enhanced by evaluating patient performance on information-retrieval tasks. Hypertext tools can be used to gather information about patients' planning abilities and their semantic understanding of the available information. The paper explores the use of hypertext for generating therapy material which works with existing methods of aphasia therapy, and highlights its importance in evaluating verbal and non-verbal abilities. Patient performance on hypertext-related tasks can be quantified with the proposed parameters which quantify the degree of language deficit through information retrieval and understanding processess. These parameters need to be tested for their importance in outcome management:whether they are sensitive enough to measure changes or not. The role of hypertext applications in developing therapy exercise is discussed. The advantages of hypertext tools in single case-studies is highlighted, and an active role for hypertext applications in aphasia management is suggested.     

Early recovery profiles of language and executive functions after left hemisphere stroke in bilingualism

ABSTRACT

Background: The nature, rate and pattern of recovery in bilingual persons with aphasia has been investigated over many years but several controversies remain. Recent evidence suggests that the relationship between executive function (EF) processes and language recovery may be distinct in bilinguals. An improved understanding of such underlying linguistic and cognitive processes may enhance assessment and treatment particularly in the acute phase. There is limited knowledge regarding how these processes interact and there remains little guidance as to the choice of an appropriate assessment battery. There is a need to develop a simple, effective battery which is sensitive to recovery processes, and in a multicultural and multilingual context, is able to distinguish normal from pathological profiles.

Aims: The research study aimed to identify an assessment battery for language and EF that is sensitive to the recovery process for South African bilingual persons with aphasia at two time periods within the first 12 weeks post stroke.

Methods and Procedures: A longitudinal comparison study was conducted at two acute rehabilitation centres. A sample of 10, second language English-speaking participants with aphasia (PWA) were assessed at two time periods within the first 12 weeks post stroke using the Comprehensive Aphasia Test (CAT) and a non-verbal EF battery. A matched control group of 19 neurologically intact bilingual, second language English speakers was assessed on the same battery on two occasions.

Outcomes and Results: A between-group analysis identified statistically significant differences between the bilingual aphasic and control groups for language assessment as well as on the EF assessment (measuring updating, inhibition and shifting). The battery of tests also distinguished testing period and was appropriate for a variety of cultural groups. Distinctive profiles emerged across time for both language and EF subtests for the PWA.

Conclusion: The combined battery appeared appropriate for the context and the results confirmed prior research suggesting that executive functioning may offer some explanations for differential recovery profiles. Exploring this distinct clinical profile may strengthen the decision-making process with regard to the type and language medium of therapy. Persistent EF deficits suggest the need for a cautionary interpretation of a bilingual advantage in the acute stage. Effective management in the acute phase of aphasia should be based on an understanding of recovery patterns, what is driving that pattern, and which cognitive deficits are contributing to the language behaviour. Delineating separate EFs and their linguistic correlates in bilinguals may aid management choices.     

Perseveration in aphasia

We developed a battery of tests to evaluate the relationship of perseveration to aphasia, and tested 44 subjects (18 with aphasia, 13 with right hemispheric lesions, 13 normal controls). Several major findings emerged: left hemispheric, posteriorly located, aphasia producing lesions also produced abundant perseverations, both verbal and non-verbal, which were primarily recurrent in type; right hemispheric lesions produced few perseverations, and these were primarily of the continuous type; more than half of the verbal recurrent perseverations of aphasia on a naming task were semantic in nature. We conclude that recurrent perseveration has a special, perhaps integral, link to language disorders of aphasia, particularly fluent aphasia associated with posterior lesions.     

Verbal coding and visual memory in aphasics

Fluent and non-fluent aphasics, non-aphasic brain-damaged patients, schizophrenics, and normal controls were tested in a non-verbal visual retention task (object-drawings, snowflakes). All groups of neurological and psychiatric patients scored lower than normal controls under a rehearsal condition. Differences levelled off when a distractor task was interpolated. While fluent aphasics were impaired with both the object-drawings and the snowflakes, non-fluent aphasics were impaired only with the latter. Results are discussed with respect to the verbal-encoding hypothesis and other theories of aphasia.     

Construct validity,external validity,and reliability for a battery of language-specific attention tasks

Background: Multiple language problems have been attributed to attentional impairments in people with aphasia. As a result, a number of investigations have examined the effectiveness of attentional treatments for improving impaired language processing. With few exceptions, all of the studies have used domain-general (nonspecific) attention training with nonlinguistic tasks as the therapeutic modality. Unfortunately, despite the well-documented associations between language and attention, these treatments have not yielded substantial improvements in language outcomes. It may be that the lack of specificity in these approaches for recruiting language-related attentional processes is a contributing factor. To address this issue, a Language-Specific Attention Treatment (L-SAT) (Peach, 2012) was proposed using language tasks that are purported to recruit attention for language processing. Further investigation into the attentional requirements of these tasks is needed.

Aims: To establish the construct validity and reliability of the baseline and probe tasks (hereafter, probe tasks) used in L-SAT in a group of healthy participants as well as to determine the external validity of these tasks in participants with aphasia.

Methods & Procedures: Twenty healthy participants and six participants with aphasia were assessed using standardized language and attention tests and an experimental battery of eight language-specific attention tasks that serve as the probe measures for this program. Correlational analyses were performed to examine the construct and external validity of the experimental tasks as well as their reliability.

Outcomes & Results: All of these language tasks were found to be independent of one another in healthy participants and to correlate strongly with at least one attention measure, with the exception of one task, which showed moderate correlations with several attention measures. Examination of the correlations among the probe tasks and the attention measures revealed a highly interpretable pattern that is consistent with the processing requirements of each task. i.e., the attentional demands suggested by these findings are reasonable and consistent with the language tasks themselves. Excellent inter- and intra-rater reliability were found for these tasks in both healthy participants and the PWA. Acceptable test-retest reliability was found in both groups for all but three of the tasks.

Conclusions: The results suggest that these probe tasks provide a valid method for recruiting language-directed attentional abilities, and therefore, may be effective for indexing attentional processing in participants with aphasia. L-SAT, which incorporates these tasks into a hierarchically organized treatment program, may offer a promising approach to treating aphasic impairments associated with attentional deficits.     

Recognition of thematic and taxonomic conceptual relations in patients with aphasia

Background: There is mounting evidence that there exist conceptual non-verbal deficits in patients with aphasia. In the current paper, taxonomic and thematic conceptual relations are the focus of interest. There is a debate surrounding this topic regarding whether they are part of the same semantic system or there are independent systems dedicated to each kind of relations.

Aims: Our aim was to study and look for possible dissociations in a group of fluent and non-fluent aphasic patients on their ability to recognise conceptual relations (taxonomic and thematic).

Methods & Procedures: Previous studies have usually proposed forced-choice tasks, which give the patients closed response options and do not allow the researcher to assess the criteria for the choice the participants have made. In the following study we assigned different types of conceptual tasks (forced choice and free choice) to a group of 25 stroke patients (7 fluent and 18 non-fluent aphasic patients), as well as 30 healthy control participants. We assessed the hit rates and the response criteria followed by the patients.

Outcomes & Results: The results showed that although all aphasic patients experienced difficulties in establishing both types of conceptual relations in verbal tasks, dissociations were observed particularly in non-verbal tasks showing poor performance in thematic relations. This was especially noticeable in non-fluent aphasic patients. Meanwhile, fluent aphasic patients showed more difficulty in establishing taxonomic relations in the pictorial free-choice task and a tendency to use thematic criteria.

Conclusion: These results support the claim that there exist separate systems for both kinds of conceptual relations. Implications for the assessment of semantic deficits in aphasic patients were discussed.     

Integrity and function of gestures in aphasia

Background: Gestures can provide an excellent natural alternative to verbal communication in people with aphasia (PWA). However, despite numerous studies focusing on gesture production in aphasia, it is still a matter of debate whether the gesture system remains intact after language impairment and how PWA use gestures to improve communication. A likely source for the contradicting results is that many studies were conducted on individual cases or in heterogeneous groups of individuals with additional cognitive deficits such as conceptual impairment and comorbid conditions such as limb apraxia.

Aims: The goal of the current study was to evaluate the integrity and function of gestures in PWA in light of cognitive theories of language–gesture relationship. Since all such theories presuppose the integrity of the conceptual system, and the absence of comorbid conditions that selectively impair gesturing (i.e., limb apraxia), our sample was selected to fulfill these assumptions.

Methods & Procedures: We examined gesture production in eight PWA with preserved auditory comprehension, no comorbidities, and various degrees of expressive deficit, as well as 11 age- and education-matched controls, while they described events in 20 normed video clips. Both speech and gesture data were coded for quantitative measures of informativeness, and gestures were grouped into several functional categories (matching, complementary, compensatory, social cueing, and facilitating lexical retrieval) based on correspondence to the accompanying speech. Using rigorous group analyses, individual-case analyses, and analyses of individual differences, we provide converging evidence for the integrity and type of function(s) served by gesturing in PWA.

Outcomes & Results: Our results indicate that the gesture system can remain functional even when language production is severely impaired. Our PWA heavily relied on iconic gestures to compensate for their language impairment, and the degree of such compensation was correlated with the extent of language impairment. In addition, we found evidence that producing iconic gestures was related to higher success rates in resolving lexical retrieval difficulties.

Conclusions: When comprehension and comorbidities are controlled for, impairment of language and gesture systems is dissociable. In PWA with good comprehension, gesturing can provide an excellent means to both compensate for the impaired language and act as a retrieval cue. Implications for cognitive theories of language–gesture relationship and therapy are discussed.