Universal and language-specific connected speech characteristics of bilingual speakers with Alzheimer’s Disease: insights from case studies of structurally distinct languages

Purpose: Connected speech analysis has been effectively utilized for the diagnosis and disease monitoring of individuals with Alzheimer’s Disease (AD). Existing research has been conducted mostly in monolingual English speakers with a noticeable lack of evidence from bilinguals and non-English speakers, particularly in non-European languages. Using a case study approach, we characterized connected speech profiles of two Bengali-English bilingual speakers with AD to: determine the universal features of language impairments in both languages, identify language-specific differences between the languages, and explore language impairment characteristics of the participants with AD in relation to their bilingual language experience. Method: Participants included two Bengali-English bilingual speakers with AD and a group of age-, gender-, education- and language-matched neurologically healthy controls. Connected speech samples were collected in L1 (Bengali) and L2 (English) using a novel storytelling task (i.e., “Frog, where are you?”). These samples were analyzed using an augmented Quantitative Production Analysis and Correct Information Unit analyses for productivity, fluency, syntactic and morpho-syntactic features, lexical and semantic characteristics. Results: Irrespective of the language, AD impacted speech productivity (speech rate and fluency) and semantic characteristics in both languages. Unique language-specific differences were noted on syntactic measures (reduced sentence length in Bengali), lexical distribution (fewer pronouns and absence of reduplication in Bengali) and inflectional properties (no difficulties with noun or verb inflections in Bengali). Among the two participants with AD, the individual who showed lower proficiency and usage in L2 (English) demonstrated reduced syntactic complexity and morpho-syntactic richness in English. Conclusion: Evidence from these case studies suggest that language impairment features in AD are not universal across languages, particularly in comparison to impairments typically associated with language breakdowns in English. This study underscores the importance of establishing connected speech profiles in AD for non-English speaking populations, especially for structurally different languages. This would in turn lead to the development of language-specific markers that can facilitate early detection of language deterioration and aid in improving diagnosis of AD in individuals belonging to underserved linguistically diverse populations

Connected speech characteristics of Bengali speakers with Alzheimer’s Disease: evidence for language-specific diagnostic markers

Background & Aim: Speech and language characteristics of connected speech provide a valuable tool for identifying, diagnosing and monitoring progression in Alzheimer’s Disease (AD). Our knowledge of linguistic features of connected speech in AD is primarily derived from English speakers; very little is known regarding patterns of linguistic deficits in speakers of other languages, such as Bengali. Bengali is a highly inflected pro-drop language from the Indo-Aryan language family. It is the seventh most spoken language in the world, yet to date, no studies have investigated the profile of linguistic impairments in Bengali speakers with AD. The aim of this study was to characterize connected speech production and identify the linguistic features affected in Bengali speakers with AD. Methods: Participants were six Bengali speaking AD patients and eight matched controls from the urban metropolis, Kolkata, India. Narrative samples were elicited in Bengali using the Frog Story. Samples were analyzed using the Quantitative Production Analysis and the Correct Information Unit analyses to quantify six different aspects of speech production: speech rate, structural and syntactic measures, lexical measures, morphological and inflectional measures, semantic measures and measure of spontaneity and fluency disruptions. Results & Conclusions: In line with the extant literature from English speakers, the Bengali AD participants demonstrated decreased speech rate, simplicity of sentence forms and structures, and reduced semantic content. Critically, differences with English speakers’ literature emerged in the domains of Bengali specific linguistic features, such as the pro-drop nature of Bengali and its inflectional properties of nominal and verbal systems. Bengali AD participants produced fewer pronouns, which is in direct contrast with the overuse of pronouns by English AD participants. No obvious difficulty in producing nominal and verbal inflections was evident. However, differences in the type of noun inflections were evident; these were characterized by simpler inflectional features used by AD speakers. This study represents the first of its kind to characterize connected speech production in Bengali AD participants and is a significant step forward towards the development of language-specific clinical markers in AD. It also provides a framework for cross-linguistic comparisons across structurally distinct and under-explored languages

Importance of task selection for connected speech analysis in patients with Alzheimer’s disease from an ethnically diverse sample

Features of linguistic impairment in Alzheimer’s disease (AD) are primarily derived from English-speaking patients. Little is known regarding such deficits in linguistically diverse speakers with AD. We aimed to detail linguistic profiles (speech rate, dysfluencies, syntactic, lexical, morphological, semantics) from two connected speech tasks – Frog Story and picture description – in Bengali-speaking AD patients. The Frog Story detected group differences on all six linguistic levels, compared to only three with picture description. Critically, Frog Story captured the language-specific differences between the groups. Careful consideration should be given to the choice of connected speech tasks for dementia diagnosis in linguistically diverse populations

Spoken Discourse Assessment and Analysis in Aphasia: An International Survey of Current Practices

Purpose: Spoken discourse analysis is commonly employed in the assessment and treatment of people living with aphasia, yet there is no standardization in assessment, analysis, or reporting procedures, thereby precluding comparison/meta-analyses of data and hindering replication of findings. An important first step is to identify current practices in acquiring, analyzing, and reporting spoken discourse information in aphasia. Thus, this study surveyed current practices, with the goal of working toward standardizing assessment, analysis, and reporting, first in research settings with subsequent implementation in clinical settings. Method: A mixed-methods (quantitative, qualitative) survey was publicized to researchers and clinicians around the globe who have collected and/or analyzed spoken discourse data in aphasia. The survey data were collected between September and November 2019. Results: Of the 201 individuals who consented to participate, 189 completed the entire survey. The majority of respondents reported barriers to utilizing discourse including transcription, coding, and analysis. The most common barrier was time (e.g., lack of time). Respondents also indicated that there was a lack of, and a need for, psychometric properties and normative data for spoken discourse use in the assessment and treatment of persons with aphasia. Quantitative and qualitative results are described in detail. Conclusions: The current survey study evaluated spoken discourse methods in aphasia across research and clinical settings. Findings from the current study will be used to guide development of process standardization in spoken discourse, and for the creation of a psychometric and normative property database

Connected speech profiles in bilinguals with AD (Dutta et al., 2024)

Purpose: Connected speech analysis has been effectively utilized for the diagnosis and disease monitoring of individuals with Alzheimer’s disease (AD). Existing research has been conducted mostly in monolingual English speakers with a noticeable lack of evidence from bilinguals and non-English speakers, particularly in non-European languages. Using a case study approach, we characterized connected speech profiles of two Bengali–English bilingual speakers with AD to determine the universal features of language impairments in both languages, identify language-specific differences between the languages, and explore language impairment characteristics of the participants with AD in relation to their bilingual language experience.Method: Participants included two Bengali–English bilingual speakers with AD and a group of age-, gender-, education-, and language-matched neurologically healthy controls. Connected speech samples were collected in first language (L1; Bengali) and second language (L2; English) using a novel storytelling task (i.e., Frog, Where Are You?). These samples were analyzed using an augmented quantitative production analysis and correct information unit analyses for productivity, fluency, syntactic and morphosyntactic features, and lexical and semantic characteristics.Results: Irrespective of the language, AD impacted speech productivity (speech rate and fluency) and semantic characteristics in both languages. Unique language-specific differences were noted on syntactic measures (reduced sentence length in Bengali), lexical distribution (fewer pronouns and absence of reduplication in Bengali), and inflectional properties (no difficulties with noun or verb inflections in Bengali). Among the two participants with AD, the individual who showed lower proficiency and usage in L2 (English) demonstrated reduced syntactic complexity and morphosyntactic richness in English.Conclusions: Evidence from these case studies suggests that language impairment features in AD are not universal across languages, particularly in comparison to impairments typically associated with language breakdowns in English. This study underscores the importance of establishing connected speech profiles in AD for non–English-speaking populations, especially for structurally different languages. This would in turn lead to the development of language-specific markers that can facilitate early detection of language deterioration and aid in improving diagnosis of AD in individuals belonging to underserved linguistically diverse populations.Supplemental Material S1. Existing studies exploring language in bilingual AD (based on Stilwell et al., 2016, and Calabria et al., 2017).Supplemental Material S2. Best Practice Guidelines for Reporting Spoken Discourse in Aphasia and Neurogenic Communication Disorders.Supplemental Material S3. A complete list and definitions of variables derived from the Quantitative Production Analysis (QPA) and Correct Information Unit (CIU) analyses.Dutta, M., Mello, T. M. D., Cheng, Y., Dash, N. S., Nandi, R., Dutt, A., & Bose, A. (2024). Universal and language-specific connected speech characteristics of bilingual speakers with Alzheimer’s disease: Insights from case studies of structurally distinct languages. Journal of Speech, Language, and Hearing Research, 67(4), 1143–1164. https://doi.org/10.1044/2024_JSLHR-23-00254</p