Direct and Indirect Treatment Effects in Multilingual People with Aphasia

Background: Successfully assessing and treating aphasia in multilingual people requires a detailed understanding of the mechanisms underlying language processing in the multilingual population, and the potential impairments to those mechanisms. The balance between spreading activation of language processes via treatment and controlling interference of competing items within the lexico-semantic networks appears to be a key factor in determining whether treatment effects generalise within and across languages in multilingual people with aphasia (Kiran, Sandberg, Gray, Ascenso, & Kester, 2013). This balance can be exploited through treatment, which, if carefully chosen, should maximise potential within- and cross-language generalisation. One treatment that has been shown to consistently result in within-language generalisation, to varying degrees, is Verb Network Strengthening Treatment (VNeST), in which thematic role assignment to given verbs is repeatedly trained, thus strengthening semantic verb networks (Edmonds, 2016). Due to the shared semantic network across languages of multilingual people (e.g., Paradis, 1993), VNeST should result in generalisation across languages of multilingual individuals with aphasia, in addition to within-language generalisation, especially when trained verbs share argument structure across languages, and when basic sentence structure is similar across languages. To date, conflicting evidence has been observed in multilingual individuals with aphasia regarding within-language and cross-language generalisation relative to the underlying and competing mechanisms of spreading activation and interference control. Aim: We investigated under which conditions generalisation is likely to occur in multilingual individuals with aphasia, using a treatment with high potential for generalisation (VNeST), in a language pair with overlapping basic word order and mostly overlapping verb argument structure. Furthermore, we investigated whether any treatment gains were maintained after treatment was discontinued. Method: Three multilingual participants with aphasia whose first-acquired language was English, and who all acquired Modern Hebrew in elementary school and reached moderate-high pre-stroke proficiency in adulthood, participated in this study. All participants received VNeST in each of their languages, in consecutive treatment blocks. English and Hebrew abilities were tested before and after each treatment block, and 4-5 weeks after treatment was discontinued, using a large battery of language tests that included comprehension and production tasks for single-words, sentences, oral connected speech and written narratives. Functional communication skills in each language were also assessed via questionnaire. Results: We found that direct treatment effects were measured in both languages, for all participants with moderate-severe aphasia in any given language, but not in mild aphasia. Within-language generalisation was also observed for all participants, but not equally for both languages. Rather, the amount and type of generalisation was qualified by order of acquisition, relative proficiencies, attrition, aphasia type and severity, and motivational factors. Cross-language generalisation was observed in each participant in one direction only, with contradictory patterns across participants. For two participants with pre-stroke high proficiency in both languages, we found support for the strong suppression of interference in the less impaired English during treatment of the more impaired Hebrew, resulting in either no cross-language generalisation to English, or a decrease in post-treatment English language performance, which we attribute to the involvement of damage to the language control network (Ansaldo & Saidi, 2014). Conversely, in the same two participants, cross-language generalisation was observed in the more impaired Hebrew after treatment in the less impaired English, likely due to a weak suppression of interference of the more impaired Hebrew, and therefore a stronger effect of spreading activation from treatment in English (Kiran et al., 2013). We observed the opposite pattern in a participant whose attrited Hebrew had never reached full proficiency pre-stroke, with treatment in his more impaired Hebrew demonstrating cross-language generalisation to his less impaired English. We attribute this to strong spreading activation of an attrited language, both generally through exposure as well as specifically through treatment. Conversely, a decrease in performance in the more impaired Hebrew after treatment in the less impaired English was attribute to rarely using Hebrew in the environment once treatment in English began, together with fluctuating motivation. Treatment gains began to decline for all participants after treatment was discontinued, with the most widespread decline in the least communicative participant, in his rarely-used language (Hebrew). Conclusion: Our study supports the competing mechanisms theory of Kiran et al. (2013), relative to factors such as order of acquisition, damage to the language control network, language of the environment, attrition, and motivational factors. Clinically, we found that VNeST is a valuable treatment option in multilingual participants with aphasia, resulting in direct treatment effects and within-language generalisation, including for a moderately proficient language that had undergone attrition for many years. Notably, we found that when treating a multilingual participant with aphasia in one language only, not only can cross-language generalisation occur or not occur, but treatment in one language can also result in a decrease in performance in the untreated language, especially if (a) the language control network is damaged, and (b) treatment is provided to the more impaired language only. Therefore, carefully monitoring language gains and losses throughout treatment is essential, in order to modify treatment plans as therapy progresses. Finally, it is necessary to consider a low dosage maintenance treatment plan relative to participants’ language and communicative environment, so that treatment gains can be appropriately maintained allowing multilingual patients with aphasia to maximise their potential in each language

Variables and Mechanisms Affecting Response to Language Treatment in Multilingual People with Aphasia

Background: Despite substantial literature exploring language treatment effects in multilingual people with aphasia (PWA), inconsistent results reported across studies make it difficult to draw firm conclusions. Methods: We highlight and illustrate variables that have been implicated in effecting cross-language treatment effects in multilingual PWA. Main contribution: We argue that opposing effects of activation and inhibition across languages, influenced by pertinent variables, such as age of language acquisition, patterns of language use, and treatment-related factors, contribute to the complex picture that has emerged from current studies of treatment in multilingual PWA. We propose a new integrated model—Treatment effects in Aphasia in Multilingual people (the TEAM model)—to capture this complexity

Strengthening the semantic verb network in multilingual people with aphasia: within- and cross-language treatment effects

In multilingual people, semantic knowledge is predominantly shared across languages.Providing semantic-focused treatment to people with aphasia has been posited to strengthenconnectivity within association cortices that subserve semantic knowledge. In multilingual people, such treatment should result in within- and cross-language generalisation to all languages, although not equally. We investigated treatment effects in two multilingual participants with aphasia who received verb-based semantic treatment in two pre-stroke highlyproficient languages. We compared within- and cross-language generalisation patterns across languages, finding within- and cross-language generalisation after treatment in the less-impaired, pre-morbidly more-proficient first-acquired language (L1). This observation supports the theory that connectivity is greater between the lexicon of a pre-morbidly more-proficient L1 and the shared semantic system than the lexicon of a pre-morbidly less-proficient later-acquired language. Our findings of within- and cross-language generalisation patterns could also be explained by both the Competing Mechanisms Theory and the theory of lingering suppression

Variables and Mechanisms Affecting Response to Language Treatment in Multilingual People with Aphasia

Background: Despite substantial literature exploring language treatment effects in multilingual people with aphasia (PWA), inconsistent results reported across studies make it difficult to draw firm conclusions. Methods: We highlight and illustrate variables that have been implicated in affecting cross-language treatment effects in multilingual PWA. Main contribution: We argue that opposing effects of activation and inhibition across languages, influenced by pertinent variables, such as age of language acquisition, patterns of language use, and treatment-related factors, contribute to the complex picture that has emerged from current studies of treatment in multilingual PWA. We propose a new integrated model—Treatment Effects in Aphasia in Multilingual people (the TEAM model)—to capture this complexity

Language mixing patterns in a bilingual individual with non-fluent aphasia

Background: Language mixing in bilingual speakers with aphasia has been reported in a number of research studies, but the reasons for the mixing and whether it reflects typical or atypical behaviour has been a matter of debate. Aims: In this study, we tested the hypothesis that language mixing behaviour in bilingual aphasia reflects lexical retrieval difficulty. Methods & procedures: We recruited a Hebrew-English bilingual participant with mild-moderate non-fluent agrammatic aphasia and assessed his languages at three timepoints. We analysed the participant’s Hebrew and English production for retrieval during single-word naming, sentences, and discourse, and identified all instances of language mixing. Outcomes & Results: We found that there was a greater frequency of language mixing during production of more difficult lexical items, namely the post-morbidly less proficient language (compared to the more proficient language), function words (compared to content words), and single-word naming (compared to retrieval in the context of connected speech tasks), but not for verbs (compared to nouns). Conclusions: In this bilingual participant with non-fluent aphasia, language mixing behaviour closely resembles lexical retrieval difficulty. Thus, we suggest that bilingual speakers with aphasia may mix their languages as a strategy to maximise communication

Ageing as a Confound in Language Attrition Research: Lexical Retrieval, Language Use, and Cognitive and Neural Changes

Adult-onset native-language attrition most often occurs following a move to an environment where a non-native language is spoken. To date, the focus of attrition research has been in identifying what aspects of language are lost and which factors are crucial for the retention or attrition of the native language. Attrition is a gradual and fairly subtle process with no clear beginning or end. To best assess the effects of attrition, researchers tend to choose study participants who have lived in a non-native environment for a decade or longer (e.g., de Bot & Clyne, 1994; Schmid, 2002). The assumption is that the longer they have been removed from the native-language environment, the greater the degree of language attrition that should be observable. However, this principle regarding length of time and its relationship to language use overlaps with another, largely ignored, phenomenon: language changes associated with ageing. Are language changes due to long-term disuse conflated with age-related language changes in older adults who experience language attrition? This chapter explores changes to the adult lexicon as a result of attrition and ageing since the lexicon is considered a vulnerable part of the language system in both attrition and ageing. We consider neurophysiological changes that may play a role in language attrition and in non-pathological ageing to speculate whether the neurobiological sources of these two processes are similar or different. If attrition and ageing exert independent effects on lexical retrieval decline, we must consider the effects of each of these factors for word retrieval for older adult bilinguals immersed in a non-native-language environment

Primary Progressive Aphasias in Bilinguals and Multilinguals

Primary progressive aphasia (PPA) is the result of neurodegeneration affecting language abilities that continue to decline as the disease progresses. There are three main variants of PPA: non‐fluent, semantic, and logopenic. Deficits may occur in different areas of language, such as lexical retrieval, auditory comprehension, syntactic structure, processing morphological components, and repetition abilities. However, the impact on language is not comparable across all individuals with PPA; rather it differs for each of the different variants based on the underlying pattern of neural change. In bilinguals or multilinguals with PPA, the language decline has an added layer of complexity. Decline may occur across the different languages in parallel, or differentially, and a number of factors may affect the pattern of decline. Recognizing the factors that most affect language decline in bilinguals and multilinguals with PPA, along with identifying the neural changes occurring in the brain, can increase our understanding of language organization in the bilingual or multilingual brain. It should be noted that language decline is not the only decline associated with PPA, as changes in cognition and behaviour have also been observed, particularly in the later stages (e.g. Rosen et al. 2006). However, language is the most salient decline in PPA so we focus on language in this chapter

Hereditary orotic aciduria identified by newborn screening

Introduction: Hereditary orotic aciduria is an extremely rare, autosomal recessive disease caused by deficiency of uridine monophosphate synthase. Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria. Newborn screening has the potential to identify and enable treatment of affected individuals before they become significantly ill.Methods: Measuring orotic acid as part of expanded newborn screening using flow injection analysis tandem mass spectrometry.Results: Since the addition of orotic acid measurement to the Israeli routine newborn screening program, 1,492,439 neonates have been screened. The screen has identified ten Muslim Arab newborns that remain asymptomatic so far, with DBS orotic acid elevated up to 10 times the upper reference limit. Urine organic acid testing confirmed the presence of orotic aciduria along with homozygous variations in the UMPS gene.Conclusion: Newborn screening measuring of orotic acid, now integrated into the routine tandem mass spectrometry panel, is capable of identifying neonates with hereditary orotic aciduria