The Influence of Aging and Neurological Impairment on Bilingual Lexical-Semantic Representation and Processing

While there is a growing body of research investigating bilingual lexical-semantic representation and processing in younger adults, few studies have employed on-line experimental methods to examine lexical-semantic representation and processing in older bilingual adults or bilingual speakers with acquired neurological impairment. Understanding the nature of bilingual language processing in older adults will provide a platform from which to better understand acquired language impairments in bilinguals, such as dementia and aphasia, and will enhance understanding of changes potentially associated with cognitive aging. Investigation of lexical-semantic processing in bilingual adults with acquired neurological injuries will improve the knowledge base from which to develop effective cognitive neuropsychological language intervention approaches for bilingual aphasia, and will further inform understanding of the neural underpinnings and functional architecture of bilingual language in healthy speakers. Thus, the aims of this thesis were to employ on-line experimental techniques to determine whether there were differences in lexical-semantic representation and processing between healthy younger and older bilingual adults, and to examine lexical-semantic processing in bilingual individuals with acquired neurological impairments. Specifically, this thesis employed a semantic priming experiment to investigate whether semantic representation is shared or separate; a cognate repetition priming experiment to explore the cross-linguistic connections between cognates and noncognates; and a synonym judgement task to compare the processing of within- and cross-language synonyms in bilingual adults. The first study in this thesis (chapter 2) employed a semantic priming paradigm to investigate whether semantic representation is shared or separate in younger bilingual adults. Although the participants showed no cross-linguistic priming, the finding of solely within-language priming (within the speaker’s dominant language) was deemed to be indicative of shared semantic representation in a group of less-proficient bilinguals, and lent support to the revised hierarchical model (RHM: Kroll & Stewart, 1994). In the second study (chapter 3), this same paradigm was employed with a group of older bilingual adults who showed priming both within and across languages, providing further support for the RHM and suggesting that the basic integrity of semantic representation is maintained in older bilingual adults. The third and fourth studies (reported in chapter 4) investigated the representation and cross-linguistic connections between cognates in comparison to noncognates using a repetition priming paradigm. The younger bilingual adults produced the anticipated cognate advantage for same language repetitions and a language-specific cognate advantage for different language repetitions. The older bilingual adults, however, showed a language-specific cognate advantage for same language repetitions but produced faster reaction times for noncognates for different language repetitions. The reversal of the cognate advantage was attributed to poorer inhibitory mechanisms in older adults, causing difficulties in selecting between form-similar lexical competitors. The fifth study (chapter 5) compared within-language and cross-language connections using a synonym judgement task with both younger and older healthy bilingual adults. Both groups showed faster processing of translation equivalents over within-language synonyms, confirming the notion that translation equivalents are more closely connected than within-language synonyms. The older bilingual adults showed a greater discrepancy between processing times for translation equivalents and within-language synonyms, suggesting that there are subtle changes in lexical-semantic connections with increased age. Chapter 6 reports the performance of two bilingual adults with neurological injury, on the semantic priming and cognate repetition priming experiments. The participant with bilingual aphasia produced semantic priming effects in only three of four conditions, suggesting a weaker connection between the English lexicon and semantic system, possibly as a result of both premorbid proficiency and postmorbid impairment. In the cognate repetition priming experiment, this participant produced results that generally mirrored those of the older bilingual adults. The participant with a cerebellar lesion only produced semantic priming effects in two conditions (one within-language and one cross-language), suggesting impaired lexical access mechanisms. On the cognate repetition priming experiment, this participant produced similar results to those of the older adults. The results from this participant lend further support to the role of the cerebellum in language processing. In summary, the findings of this thesis suggest that the general integrity of bilingual lexical-semantic representations are maintained and accessible with increased age, in relation to the representation of semantic meaning, cognates and noncognates, and cross-linguistic connections between within-language synonyms and translation equivalents. There are, however, subtle changes that occur in relation to bilingual lexical access in older bilingual adults, particularly for lexical items that are similar in form. The bilingual individuals with neurological impairment showed changes in accessing lexical-semantic representations that were over and above those that can be attributed to normal aging processes. It is anticipated that these findings will enhance our understanding of language processing mechanisms in older bilingual adults and bilinguals with neurological impairment, and can potentially be used to inform the development of impairment-level treatment methods for bilingual aphasia

Community-based interventions for building social inclusion of refugees and asylum seekers in Australia: A systematic review

As refugee and asylum seeker numbers increase in Australia, their effective integration into society is facilitated by inclusion in social, economic and community life. This systematic review of the literature explored community-based programs that contribute to inclusion and social participation of refugees and asylum seekers in Australia. Four scholarly databases were searched for articles published between 2007 and 2017 resulting in five articles which met inclusion criteria. Although the studies identified were of variable quality, the findings suggest a number of factors that facilitate program effectiveness. These included where: (a) English language and communications skills were considered; (b) programs built on refugees’ own skills and experience prior to resettlement; (c) volunteers and mentors were involved; and (d) participants engaged in diverse projects that enabled new connections. The review highlights the paucity of well-researched interventions that build social inclusion of refugees and asylum seekers in Australia. Emerging evidence suggests that community-based programs can positively increase social inclusion and connectedness amongst refugees and asylum seekers. Additional well-designed programs and evaluation of such programs are needed to better understand and identify effective interventions targeting social inclusion of refugees and asylum seekers

Improved word comprehension in Global aphasia using a modified semantic feature analysis treatment

Limited research has investigated treatment of single word comprehension in people with aphasia, despite numerous studies examining treatment of naming deficits. This study employed a single case experimental design to examine efficacy of a modified semantic feature analysis (SFA) therapy in improving word comprehension in an individual with Global aphasia, who presented with a semantically based comprehension impairment. Ten treatment sessions were conducted over a period of two weeks. Following therapy, the participant demonstrated improved comprehension of treatment items and generalisation to control items, measured by performance on a spoken word picture matching task. Improvements were also observed on other language assessments (e.g. subtests of WAB-R; PALPA subtest 47) and were largely maintained over a period of 12 weeks without further therapy. This study provides support for the efficacy of a modified SFA therapy in remediating single word comprehension in individuals with aphasia with a semantically based comprehension deficit

Assessment and rehabilitation of acquired communication disorders in Aboriginal and Torres strait islander adults with stroke or traumatic brain injury: a retrospective chart review

Purpose: Speech-language pathologists’ (SLP) management practices for Aboriginal and Torres Strait Islander adults with acquired communication disorder (ACD), following stroke or traumatic brain injury (TBI), are not well understood. This study explores SLPs’ management approaches for ACDs for Aboriginal and Torres Strait Islander adults post-stroke or TBI. Materials and methods: SLPs’ documented notes were analysed from a two-year retrospective medical record review of Aboriginal and Torres Strait Islander adults (≥18 years), admitted to a regional Queensland hospital with principal diagnoses of stroke or TBI. Results: SLPs frequently used informal approaches to assess ACDs. English-language formal assessment tools were also used in conjunction with the informal approaches. ACD diagnosis was more common in stroke than TBI patients. One-third of patients with ACD received inpatient rehabilitation at the study site. SLPs infrequently documented cultural or linguistic adaptions to assessment or interventions. Conclusions: Informal approaches to assess ACDs were commonly employed which may be because they are perceived to be more culturally appropriate. Clinical guidelines for stroke and TBI should accommodate the diversity of cultures and languages. Better consideration of Aboriginal and Torres Strait Islander communication styles and incorporation of these into SLP ACD management approaches may facilitate accurate diagnosis and culturally safe rehabilitation services

What do people with aphasia think about their health care? Factors influencing satisfaction and dissatisfaction

Background: Patient experience and satisfaction play an integral role in driving and directing quality improvement in health care. Although there is an increasing body of literature examining patient satisfaction with health careincluding that of stroke patientsfew studies have sought to capture the views of patients with aphasia. As a result, the experiences and opinions of people with aphasia on this subject remain unheard. In order to evaluate and improve health care for people with aphasia, there is a need to explore their experiences and resulting levels of satisfaction or dissatisfaction with their health care. Aims: This study aimed to explore the factors influencing the satisfaction and dissatisfaction of people with aphasia with regards to their health care. Methods & Procedures: A qualitative, descriptive phenomenological research approach was used. Semi-structured in-depth interviews with 50 participants with aphasia were analysed using qualitative content analysis to identify both categories and themes of health-care satisfaction. Outcomes & Results: Seven categories (areas of care) were identified as influencing participant satisfaction and dissatisfaction: (1) Forming Relationships; (2) Manner and Methods of Service Delivery; (3) Information, Communication and Knowledge; (4) Structure and Relevance of Therapy; (5) Organisational Management; (6) Individual Support; and (7) Positivity and Improvement. In addition, three core themes (described as Information and Communication, Dignity and Respect, and Control and Independence) and two secondary themes (Trust and Support and Understanding) were identified as being overarching areas of influence, appearing across the seven areas of care. Conclusions: This study has identified specific factors and values contributing to the satisfaction and dissatisfaction of people with aphasia with their health care. The findings may enable health providers to better understand the needs of people with aphasia and to implement appropriate improvements to health care and service delivery

Clinical profile of Aboriginal and Torres Strait Islander adults with stroke and traumatic brain injury at a regional Australian hospital: a retrospective chart audit

Background: The clinical profile of Aboriginal and Torres Strait Islander adults admitted to hospital with neurological injury is not well documented. Understanding these profiles may enable health professionals to provide more culturally responsive health care for this patient group. This study aimed to report the clinical profile of Aboriginal and Torres Strait Islander adults admitted to a regional Queensland hospital due to stroke or traumatic brain injury (TBI). Method: A 2-year retrospective medical record review of Aboriginal and Torres Strait Islander adults (≥18 years) admitted to a regional Queensland hospital with principal diagnoses of stroke or TBI. Results: There were 132 Aboriginal and Torres Strait Islander adult stroke (51.5%) or TBI (48.5%) admissions. The mean ages were 56.7 years for stroke and 42.7 years for TBI. The majority of patients (83.3%) were of Aboriginal descent with others identifying as Torres Strait Islander only, or both Aboriginal and Torres Strait Islander. Patients were from 26 diverse home locations across northern Australia, primarily Outer Regional or Remote/Very Remote geographical locations. All patients’ language backgrounds were documented as English only. Over 90% of stroke and 50% of TBI patients presented with medical co-morbidities. Conclusions: Patients had diverse geographical locations and cultural backgrounds, with many likely impacted by dislocation from home and country, as well as potential delays in receiving treatment. Despite this diversity, English was documented in patients’ medical records as their only language. The majority of patients also presented with multiple medical co-morbidities. Health professionals should consider these factors to ensure patients receive optimum and culturally responsive health care

Speech-language pathology services for Indigenous Australian adults with acquired communication disorders: a systematic quantitative literature review

This review aimed to describe: a) experiences of Indigenous Australian adults with ACDs; b) current speech-language pathology (SLP) practices with this population, and c) research methodologies employed to explore these factors in previous research. A systematic quantitative literature review was conducted across five databases using a priori search inclusion/exclusion criteria and search parameters relevant to the aims. Studies published in peer-reviewed journals up to February 2016 were considered in the review. Six studies met criteria for inclusion. Two described experiences of Indigenous Australian adults with ACDs (as well as significant others). Four studies related to current SLP practice with this population. Experiences specific to Indigenous Australian adults with ACDs living outside the state of Western Australia, or those actively engaged in the acute hospital setting have not been included in studies to date. Research relating specifically to SLP services for Indigenous Australian adults with ACDs following neurological injury is an emerging area, with all of the studies generated since 2012. SLPs report several barriers to service provision including a lack of knowledge, confidence and culturally appropriate resources; and challenges working with Indigenous Liaison Officers and interpreters. Future research should explore how speech-language pathologists diagnose and manage ACDs in this population, how SLPs engage with relevant stakeholders, and should address the specific needs of the Torres Strait Islander population. Qualitative research approaches, including collaboration with Indigenous Reference Groups and engagement of Indigenous research assistants contributes to culturally safe research approaches and is congruent with ethical guidelines for this population

The influence of aging and aphasia on bilingual semantic organization

Background: In managing bilingual aphasia, effective therapy techniques should be based on a clear understanding of bilingual language organization and the impact of aphasia on bilinguallexico-semantic relations. Whilst several studies have employed semantic priming to investigate the nature of bilingual semantic representation in younger adult bilinguals, few studies have investigated on-line semantic processing in older adult bilinguals or bilingual speakers with aphasia. In younger bilingual adults, evidence of cross-language priming is posited to be indicative of shared semantic representation across languages. The present study employed a bilingual semantic priming task to investigate whether cross-language priming effects would be preserved in older adult bilinguals and following neurological injury. \ud \ud Method: Twenty bilingual Italian/English speakers (13 female, 7 male) aged between 47 and 80 years (mean = 62 years) participated in the experiment. The experiment was also completed by one 70-year-old female Italian/English speaker with bilingual aphasia following a left (VA. Participants were presented with pairs of auditory stimuli in which the first stimulus was a real Italian or English word and the second stimulus was either a real word or nonword. There were four conditions in which word pairs were related: Italian-Italian, English-English, English-Italian and Italian-English and four corresponding unrelated and nonword conditions. Participants were required to make speeded lexical decisions on the second stimulus in each pair and indicated real words with a button press. No response was required for nonwords.\ud \ud Results: For the older bilingual adults, mean reaction times from the related and unrelated conditions were analysed using a linear mixed model with the within-subjects factors of relatedness, language congruence and target language and the covariate English exposure. The analysis revealed significant main effects for relatedness, language congruence and target language as well as a target language by English exposure interaction. Further pair-wise comparisons demonstrated that priming occurred in all of the within-language and cross-language conditions. This pattern was shown by participants with both less English exposure and more English exposure. In contrast, the participant with bilingual aphasia showed a reaction time advantage for related pairs only in the two within-language conditions. No such pattern was found in the cross-language conditions.\ud \ud Discussion: The results indicate that both cross-language and Within-language priming is found in older adult bilinguals which suggests that shared bilingual semantic representation is unaffected by aging mechanisms. The lack of cross-language priming, however, in the participant with bilingual aphasia suggests that neurological insult may disturb cross-language semantic connections whilst within-language semantic links appear to be preserved. The absence of cross-language priming suggests separate semantic storage for each language in the participant with aphasia.\ud \ud Conclusion: The present study results suggest that aphasia may disrupt cross-linguistic semantic connections whereas withinlanguage semantic links may be preserved. Further research is required to verify whether this pattern is consistently demonstrated in bilingual aphasia and to explore the implications for devising effective language therapy techniques

"... Trial and error ...": speech-language pathologists' perspectives of working with Indigenous Australian adults with acquired communication disorders

Purpose: This study explored speech-language pathologists' (SLPs) perspectives about factors that influence clinical management of Aboriginal and Torres Strait Islander adults with acquired communication disorders (e.g. aphasia, motor speech disorders). Method: Using a qualitative phenomenological approach, seven SLPs working in North Queensland, Australia with experience working with this population participated in semi-structured in-depth interviews. Qualitative content analysis was used to identify categories and overarching themes within the data. Result: Four categories, in relation to barriers and facilitators, were identified from participants' responses: (1) The Practice Context; (2) Working Together; (3) Client Factors; and (4) Speech-Language Pathologist Factors. Three overarching themes were also found to influence effective speech pathology services: (1) Aboriginal and Torres Strait Islander Cultural Practices; (2) Information and Communication; and (3) Time. Conclusion: This study identified many complex and inter-related factors which influenced SLPs' effective clinical management of this caseload. The findings suggest that SLPs should employ a flexible, holistic and collaborative approach in order to facilitate effective clinical management with Aboriginal and Torres Strait Islander people with acquired communication disorders

Domain-general cognitive control and domain-specific language control in bilingual aphasia: a systematic quantitative literature review

For successful language production in a target language, bilingual individuals with aphasia must inhibit interference from the non-target language. It is currently unknown if successful inhibition of a non-target language involves general cognitive control (domain-general cognitive control) or whether it is control specific to linguistic mechanisms (domain-specific language control) during language production. The primary aim of this systematic quantitative literature review was to identify and synthesize available evidence, in relation to bilinguals with aphasia, for these two mechanisms. We conducted a literature search across five databases using a set of inclusion/exclusion criteria designed for the review. We extracted data from twenty studies reporting original research in bilinguals with aphasia. The results provided evidence for both domain-general cognitive control and domain-specific language control mechanisms, although most studies showed the involvement of domain-general cognitive control. Available neuroimaging data indicated that the neural regions involved in domain-general language control in bilinguals with aphasia were the anterior cingulate cortex, caudate nucleus, basal ganglia, and the frontal lobe. Theoretical implications for the bilingual inhibitory control model, clinical implications for assessment and treatment of cognitive control abilities in bilinguals with aphasia as well the need for future research are discussed