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

Abstract

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.

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

“…Additionally, the greater improvement in the less-impaired language is also consistent with the Competing Mechanisms Theory, according to which patterns of within- and cross-language generalisation will be determined by the relative strengths of the spreading activation mechanism and the interference control mechanism, depending on relative post-stroke abilities of each language (e.g., Goral & Lerman, 2020; Green, 1998; Kiran et al, 2013). In their landmark paper on within- and cross-language generalisation patterns, Kiran and colleagues (2013) suggest that within-language generalisation that occurs without cross-language generalisation is more likely in participants whose post-stroke language impairment is differential rather than parallel.…”

“…However, considerable empirical data challenges this hypothesis (e.g., Abutalebi, Rosa, Tettamanti, Green & Cappa, 2009; Ansaldo & Saidi, 2014; Croft, Marshall, Pring & Hardwick, 2011; Faroqi-Shah, Frymark, Mullen & Wang, 2010; Goral, Rosas, Conner, Maul & Obler, 2012; Goral, Naghibolhosseini & Conner, 2013; Kiran, Sandberg, Gray, Ascenso & Kester, 2013; Knoph, Simonsen & Lind, 2017; Lerman, Edmonds & Goral, 2018). Therefore, several researchers have hypothesised that patterns of generalisation are likely related to differences in proficiency and use of each language (e.g., Edmonds & Kiran, 2006; Goral et al, 2012; Nadeau, 2019), the balance between the language network and the language control network (e.g., Goral et al, 2013; Kiran et al, 2013; Li, Li & Kiran, 2020), and the specific type of treatment provided (Goral & Lerman, 2020).…”

“…Potentially, the most efficient way to rehabilitate language impairment in multilingual people with aphasia would be to provide treatment that generalises not only to untrained stimuli and untrained contexts in the treated language (within-language generalisation) but also to untrained stimuli and untrained contexts in the untreated language (cross-language generalisation – e.g., Boyle, 2004; Goral & Lerman, 2020; Lerman et al, 2018). Data from both monolingual and multilingual people with aphasia indicate that within-language generalisation of single-words often occurs, especially after semantic treatment (rather than phonological treatment, for example) and to semantically-related words more than non-semantically-related words (e.g., Faroqi-Shah et al, 2010; Greenwald, Raymer, Richardson & Rothi, 1995; Howard, Patterson, Franklin, Orchard-Lisle & Morton, 1985; Kiran et al, 2013; Law, Wong, Sung & Hon, 2006; Marshall, Pound, White-Thomson & Pring, 1990; Nickels & Best, 1996; Peach & Reuter, 2010; Webster & Whitworth, 2012).…”

Executive control in bilingual aphasia: a systematic review

“…Bilingualism has implications for the diagnosis and rehabilitation of aphasia. Treatment of both languages is not always feasible, and the likelihood of cross-linguistic transfer depends on many factors (Goral & Lerman, 2020). In addition, it is difficult to ascertain the premorbid level of proficiency in each language.…”

Multilevel factors predict treatment response following semantic feature-based intervention in bilingual aphasia

“…Previous bilingual aphasia rehabilitation research has mainly focused on the efficacy of language treatment and the effects of bilingualism-related variables on response to treatment in this population. Studies addressing these questions have provided some evidence for positive treatment outcomes in particular in the treated language (see ; also see Faroqi-Shah et al, 2010 for a review) and evidence for modulatory effects of language proficiency on overall response to treatment (see Goral & Lerman, 2020 for a review).…”