Discourse Production Across the Adult Lifespan: Microlinguistic Processes.

Successful spoken discourse requires a speaker to be informative to deliver a coherent, meaningful message. The informativeness of discourse can be conveyed by the variety of vocabulary produced (i.e., lexical diversity [LD]), the typicality of vocabulary items used (i.e., core lexicon [CL]), and the amount of relevant content produced (i.e., information units). Yet, it is well documented that older adults produce less informative content compared to younger adults despite relatively subtle changes to LD. The typicality of core lexical items has not been assessed in healthy aging. Paradoxically, these results indicate that some aspects of discourse informativeness remain stable or even improve across the adult lifespan, while other aspects decline. The purpose of the current study is to understand how microlinguistic processes of informativeness change across the adult lifespan. The cross-sectional study included narrative language samples from two wordless picture books collected from 420 healthy participants between 20 and 89 years old. LD and percent of correct information units (%CIUs) were analyzed, as well as CL nouns and verbs. The results indicate that %CIUs and CL nouns demonstrate a quadratic decline starting around the ages of 40 and 60, respectively. LD shows a slight linear decline as a function of age. CL verbs are resistant to age-related changes but are influenced greater by education. The differing findings across the microlinguistic measures can be explained by the weakened connections within the language system and the differential characteristics of the measures. The findings contribute to the aging literature by systematically identifying the trajectory of how variables of informativeness change with age.

A preliminary investigation on core lexicon analysis in dementia of the Alzheimer's type.

BACKGROUND: Core lexicon (CL) analysis is a time efficient and possibly reliable measure that captures discourse production abilities. For people with aphasia, CL scores have demonstrated correlations with aphasia severity, as well as other discourse and linguistic measures. It was also found to be clinician-friendly and clinically sensitive enough to capture longitudinal changes in aphasia. To our knowledge, CL has never been investigated in individuals with neurologically progressive disease. AIMS: As a preliminary investigation, we sought to investigate (1) whether CL scores correlate with dementia severity, (2) whether CL scores correlate with measures of discourse quality, and (3) whether CL scores correlate with other measures of lexical/semantic access. METHODS & PROCEDURES: Twelve participants with a cognitive impairment associated with dementia of the Alzheimer's type (DAT) completed several measures of language and cognitive ability, as well as provide a language sample from the wordless picture book, Picnic. RESULTS & CONCLUSION: Results are informative, as they provide insight into characteristics of CL and provide support for potential use of CL in individuals with neurologically progressive disease. The results indicated that CL scores do correlate with dementia severity and several measures of language ability, indicating they may provide a useful measure of language abilities in DAT, but more research is needed. WHAT THIS PAPER ADDS: What is already known on the subject Core lexicon (CL) analysis is an assessment measure of discourse ability, most closely related to informativeness or productivity, used in aphasiology that is easier to use and less time consuming than previous measures of informativeness, such as correct information units or type-token ratio (TTR). For people with aphasia, CL analysis correlates with aphasia severity, measures of informativeness, as well as other measures of discourse quality. It has also been shown to be faster and more reliable between scorers than other informativeness measures. What this study adds Core lexicon analysis is a new simple and online method for assessing the informativeness of a discourse sample without the need to record or transcribe the language sample. CL is receiving a lot of attention in aphasia, correlating with everything from aphasia severity to measures of productivity and lexical access, as well as measures of informativeness. Unfortunately, no one has investigated CL analysis in dementia. The study demonstrates the first evidence that CL analysis may be a useful measure for determining dementia severity and language quality in people with dementia. What are the clinical implications of this work? Core lexicon analysis may provide clinicians and researchers with an easy method for assessing the discourse of people with a cognitive impairment associated with dementia of the Alzheimer's type. This will improve initial assessment, as well as improve ongoing language assessment that may provide clues into their functional ability to communicate effectively.

Light verb production in healthy ageing and dementia.

BACKGROUND: Light verbs are highly frequent and semantically impoverished words. It is currently not known whether light verb production in discourse tasks differs by age or for people with dementia of the Alzheimer's type (DAT). AIMS: The purpose of the current study was two-fold: (1) to determine whether there is a relationship between age and the proportion of light verbs produce during a narrative discourse task; and (2) to determine whether people with DAT produce a different proportion of light verbs compared with neurotypical adults. METHODS & PROCEDURES: A total of 469 neurotypical adults and 12 participants with DAT produced narratives from a wordless picture book. OUTCOME & RESULTS: The results indicated that light verb production increases as a function of age, even when controlling for education, and people with DAT produced a higher light verb-word ratio compared with neurotypical adults when matched for age and education. CONCLUSION & IMPLICATION: Light verb use may increase as a function of age due to declines in retrieval ability. These declines are not only more pronounced in people with DAT, but also semantic knowledge deficits may contribute to a reliance on light verbs. WHAT THIS PAPER ADDS: Light verbs are typically some of the first verbs learned due to their simple semantic construction and high frequency. However, two things are unknown: (1) how light verbs changed across the adult lifespan; and (2) whether cognitive impairment changes light verb production. The study found that light verb production increases as a function of age, and that people with DAT used a higher ratio of light verbs to words in a narrative task compared with neurotypical adults. However, despite the findings, more research is needed to determine their clinical utility. Future research may wish to investigate whether light verbs (1) facilitate comprehension in older adults or (2) may be used in cognitive-linguistic assessments for cognitive impairments.

Improving Functional Communication Outcomes in Post-Stroke Aphasia via Telepractice: An Alternative Service Delivery Model for Underserved Populations.

Many persons with aphasia (PWA) have limited access to speech-language treatment (SLT) due to limited funding, speech-language pathologist shortages, geographical barriers, physical disabilities, transportation barriers, and the COVID-19 pandemic. The purpose of this study was to determine if telepractice is an effective and feasible service delivery model for PWA. Ten PWA completed 8 hours of remote treatment over 4 weeks. Synchronous telepractice sessions employed Oral Reading for Language in Aphasia (ORLA) and Conversational Script Training (CST). Pre- and post-assessment outcome measures included the Communication Activities of Daily Living-3 (CADL-3) and the Communication Confidence Rating Scale for Aphasia (CCRSA). Participants completed a telepractice satisfaction survey following post-assessment. All participants demonstrated improvements in CCRSA scores, total words produced correctly on trained CST stimuli, and total words produced correctly on trained ORLA stimuli. No differences were noted in CADL-3 scores. All participants were highly satisfied with telepractice as a service delivery model.

Development of a measure of function word use in narrative discourse: core lexicon analysis in aphasia.

BACKGROUND: Although discourse-level assessments contribute to predicting real-world performance in persons with aphasia (PWA), the use of discourse measures is uncommon in clinical settings due to resource-heavy procedures. Moreover, assessing function word use in discourse requires the arduous procedure of defining grammatical categories for each word in language transcripts. AIMS: The purpose of this exploratory study was twofold: (1) to develop core function word lists as a clinician-friendly means of evaluating function word use in discourse; and (2) to examine the ability of the core function word measure to differentiate PWA from cognitively healthy adults and persons with fluent aphasia from non-fluent aphasia. METHODS & PROCEDURES: The 25 most commonly used function words (core function words) were extracted from narrative language samples from 470 cognitively healthy adults, which were divided into seven age groups (20s, 30s, 40s, 50s, 60s, 70s and 80s). The percent agreement of core function words for 11 PWA (fluent aphasia = 5; non-fluent aphasia = 6) and 11 age- and education-matched controls were then calculated. Percent agreement for the core function words produced was compared between the controls and the PWA group, and between participants with fluent aphasia and non-fluent aphasia. OUTCOMES & RESULTS: The results indicated that PWA produced fewer core function words from the lists than the control group, and that core function word use was strongly correlated with aphasia severity. Persons with non-fluent aphasia produced fewer core function words than those with fluent aphasia, although this could be a confound of aphasia classification from the use of the Western Aphasia Battery (WAB)-Revised. CONCLUSIONS & IMPLICATIONS: Core function word lists consisting of a limited number of items for quantifying function word use in discourse remain in a nascent stage of development. However, the findings are consistent with previous studies analysing the total production of function words in language samples produced by PWA. Therefore, core function words may potentially serve as a clinician-friendly manner of quantifying function words produced in discourse. What this paper adds What is already known on the subject Function word analysis in discourse requires arduous processes of identifying the error production and grammatical category of function words in discourse. Previous studies have demonstrated that core lexicon measures are an efficient, simple means of quantifying discourse in PWA. However, function words have never been considered for generating an independent core lexicon list. What this paper adds to existing knowledge As an exploratory study, we focused primarily on developing a clinician-friendly measure to evaluate function word production in discourse, motivated by the idea of an adaptation strategy within the core lexicon framework. Our findings demonstrated that by using a simple scoring system that the core lexicon measure provides, we differentiated the control group from the PWA group, and persons with fluent aphasia from persons with non-fluent aphasia. Additionally, we found significant correlations between function word production and aphasia severity determined by WAB Aphasia Quotient (AQ). What are the potential or actual clinical implications of this work? The results add empirical evidence for the utility of core function word lists for quantifying function word usage in discourse in PWA. Counting the presence and absence of function words in discourse will allow clinicians to avoid labour-intensive preparatory work, and to obtain useful diagnostic information in a less time-consuming way.

Measuring word retrieval in narrative discourse: core lexicon in aphasia.

BACKGROUND: Discourse analysis procedures are time consuming and impractical in a clinical setting. Critical to clinicians are simple and informative discourse measures that require minimal time and labour to complete. Many studies, however, have overlooked difficulties that clinicians face. We recently developed core lexicon lists for nouns, verbs, adjectives and adverbs for two narrative discourse tasks with healthy control groups. Core lexicon lists consist of important lexical items required to produce coherently meaningful discourse in response to discourse tasks. Measuring core lexicon is useful for quantifying word retrieval impairments at the discourse level in clinical populations. AIMS: To apply an age-based core lexicon list for nouns, verbs, adjectives and adverbs for the wordless picture books Good Dog Carl (1985) and Picnic (1984) and to determine how well the lists measured linguistic impairments in persons with aphasia (PWA). MATERIALS & METHODS: Lemma forms were extracted from 470 control participants who were divided into seven age groups. Twenty-five core lexicons were identified for four word classes (nouns, verbs, adjectives and adverbs) among the seven age groups. The nouns, verbs, adjectives and adverbs for each PWA (N = 11) were then compared with the core lexicon for their respective age group. Per cent agreement was computed by comparing the number of total items within each list to the number of items that PWA produced. A Spearman's correlation coefficient was computed between the WAB-R AQ and the per cent agreement for each word type for PWA. OUTCOMES & RESULTS: The percentage of agreement for each word type among the age cohorts ranged between 56% and 96%. Of the four word types, core verbs significantly correlated with the WAB AQs for both discourse tasks. A post-hoc analysis found significant differences between fluent and non-fluent aphasia for core verbs. CONCLUSIONS & IMPLICATIONS: Core lexicon analysis appears to be a practical way to capture impairments in word retrieval at the discourse level. Core verbs may be a better indicator to understand holistic language performances for PWA. Use of the core lexicon checklist can serve as an option to reconcile ecological validity with clinical usability.

Discourse-based treatment in mild traumatic brain injury.

BACKGROUND: Individuals with traumatic brain injury (TBI) present with numerous discourse deficits associated with impairments to the linguistic system and other cognitive systems. Individuals with TBI may produce discourse that is lacking important information and poorly organized, as well as containing numerous coherence disrupting elements. Yet there are few studies directly addressing discourse deficits in individuals with TBI to guide clinicians. AIMS: The purpose of the study was to determine if discourse processing treatment improved the discourse production in individual with TBI. Aims of the study included determining if the discourse processing treatment improved completeness and informativeness in TBI discourse samples. METHODS & PROCEDURES: The study included three participants with mild-to-moderate TBI. The study utilized an A-B with maintenance design that incorporated components of functional practice, structured cues in the form of comprehension questions and story guide, and meta-cognitive and meta-linguistic processes. Discourse samples were obtained for baseline, treatment, and maintenance one-week and one-month post treatment. Stimuli included 12 sequential pictures, as well as a single picture and a recount probe. OUTCOMES & RESULTS: All participants demonstrated small gains in completeness and informativeness for treated items, and 2 of 3 participants demonstrated a medium therapeutic effect for untreated stimuli. Participants also produced discourse with fewer errors for both treated and untreated stimuli after treatment with no therapeutic effect to a small effect for the generalization stimuli. CONCLUSIONS: The study demonstrated that the discourse processing treatment is capable of producing small therapeutic effects that persisted one-month post treatment in adults with mild-to-moderate TBI.

Working Memory in Aphasia: Considering Discourse Processing and Treatment Implications.

Evidence suggests that persons with aphasia (PWAs) present with working memory impairments that affect a variety of language tasks. Most of these studies have focused on the phonological loop component of working memory and little attention has been paid to the episodic buffer component. The episodic buffer, as a limited capacity, multimodal system that binds and integrates information from the phonological loop, visuospatial sketchpad, and long-term memory would likely be involved in discourse processing. The purposes of this article were to (1) review discourse level deficits associated with aphasia, (2) describe how a deficit at the level of the episodic buffer could cause such deficits, (3) to review discourse treatment approaches for PWAs, and (4) present preliminary results from a novel discourse treatment study for PWAs.

Semantic Knowledge Use in Discourse: Influence of Age.

Semantic memory is relatively stable across the lifespan (Rönnlund, Nyberg, & Bäckman, 2005; Spaniol, Madden, & Voss, 2006); however, most research has been conducted at the single concept level. Few researchers have examined how semantic knowledge is used in discourse. The purpose of the study, then, was to determine the proportion of semantic knowledge and category domains used in discourse produced by younger and older participants. Cognitively healthy, younger (n=30, 20-39) and older (n=30; 60-89) participants told stories that were transcribed and coded for 10 domains of semantic knowledge and also living and nonliving things. Results indicated group differences for the proportion of semantic knowledge type, sound, and for the category type, living things. These findings extend previous research on semantic features into the realm of discourse and indicate the importance of studying semantic features and categories within discourse.

Semantic Knowledge Use in Discourse Produced by Individuals with Anomic Aphasia.

BACKGROUND: Researchers have demonstrated that people with aphasia (PWA) have preserved semantic knowledge (Dell et al., 1997; Jefferies & Lambon Ralph, 2006). However, Antonucci (2014) demonstrated that some PWA have impaired access to certain types of knowledge more than others. Yet, all these studies used single concepts. It has not been demonstrated whether PWA have difficulty accessing certain types of features within a discourse sample. AIMS: The main goals of this study were to determine if semantic knowledge and two category types were used differently within discourse produced by participants with anomic aphasia and healthy controls. METHOD & PROCEDURES: Participants with anomic aphasia (n=19) and healthy controls (n=19) told stories that were transcribed and coded for 10 types of semantic knowledge and two category types, living and nonliving things. OUTCOMES & RESULTS: A Poisson regression model was conducted. The results indicated a significant difference between the groups for the semantic knowledge types, sound and internal state, but no difference was found for category types. Yet the distribution of semantic knowledge and category types produced within the discourse samples were similar between the groups. CONCLUSION: PWA might have differential access to certain types of semantic knowledge within discourse production, but it does not rise to the level of categorical deficits. These findings extend single-concept research into the realm of discourse.