Evolution of phonemic word fluency performance in post-stroke aphasia

Normative Data for Single-Letter Controlled Oral Word Association Test in Older White Australians and Americans, African-Americans, and Hispanic/Latinos

Background

The Controlled Oral Word Association Test (COWAT) is a commonly used measure of verbal fluency. While a normal decline in verbal fluency occurs in late adulthood, significant impairments may indicate brain injury or diseases such as Alzheimer's disease. Normative data is essential to identify when test performance falls below expected levels based on age, gender, and education level.

Objective

This study aimed to establish normative performance data on single-letter COWAT for older community-dwelling adults.

Methods

Over 19,000 healthy men and women, without a diagnosis of dementia or a Modified Mini-Mental State Examination score below 77/100, were recruited for the ASPREE trial. Neuropsychological assessments, including the COWAT with letter F, were administered at study entry.

Results

Median participant age was 75 years (range 65-98), with 56.5% being women. The majority of participants had 9-11 years of education in Australia and over 12 years in the U.S. The COWAT performance varied across ethno-racial groups and normative data were thus presented separately for 16,335 white Australians, 1,084 white Americans, 896 African-Americans, and 316 Hispanic/Latinos. Women generally outperformed men in the COWAT, except for Hispanic/Latinos. Higher education levels consistently correlated with better COWAT performance across all groups, while the negative association with age was weaker.

Conclusions

This study provides comprehensive normative data for the COWAT stratified by ethno-racial groups in Australia and the U.S., considering age, gender, and education level. These norms can serve as reference standards for screening cognitive impairments in older adults in both clinical and research settings.

Acoustic and phonemic processing are impaired in individuals with aphasia

Acoustic and phonemic processing are understudied in aphasia, a language disorder that can affect different levels and modalities of language processing. For successful speech comprehension, processing of the speech envelope is necessary, which relates to amplitude changes over time (e.g., the rise times). Moreover, to identify speech sounds (i.e., phonemes), efficient processing of spectro-temporal changes as reflected in formant transitions is essential. Given the underrepresentation of aphasia studies on these aspects, we tested rise time processing and phoneme identification in 29 individuals with post-stroke aphasia and 23 healthy age-matched controls. We found significantly lower performance in the aphasia group than in the control group on both tasks, even when controlling for individual differences in hearing levels and cognitive functioning. Further, by conducting an individual deviance analysis, we found a low-level acoustic or phonemic processing impairment in 76% of individuals with aphasia. Additionally, we investigated whether this impairment would propagate to higher-level language processing and found that rise time processing predicts phonological processing performance in individuals with aphasia. These findings show that it is important to develop diagnostic and treatment tools that target low-level language processing mechanisms.

Validation and Normative Data on the Verbal Fluency Test in a Peruvian Population Ranging from Pediatric to Elderly Individuals

In neuropsychological evaluation, verbal fluency is a crucial measure of cognitive function, but this measure requires standardized and normative data for use. The present study aimed to obtain validation and normative data for the verbal fluency task in the Peruvian population, with participants ranging from 6 to 94 years and varying in age, educational level, and sex. We recruited 2602 healthy individuals and used linear regression analysis to determine the effect of age, sex, and educational level. We also evaluated internal consistency between categories and phonological tasks with Cronbach's alpha and Pearson's correlation analysis and calculated test-retest reliability after three months. We found significant effects of age, educational level, and sex on phonological and semantic fluency. Participants with more than 12 years of education had the highest scores overall. Regarding age, middle-aged participants (between 31 and 40 years old) had the highest scores; scores gradually decreased outside of this age range. Regarding sex, men performed better than women. These results will increase the ability of clinicians to precisely determine the degree to which verbal fluency is affected in patients of different ages and educational levels.

Validity evidence for the Cognitive Screening Test in Stroke Patients

Abstract Cognitive deficits are common among post-stroke patients. Cognitive impairments of this sort are mediated by age and education. In Brazil, the only specific cognitive screening tool designed for post-stroke patients is the Cognitive Screening Test (Triagem Cognitiva - TRIACOG). The goal of this study was to investigate validity evidence related to external variables for the TRIACOG. Our sample included 153 adults and elderly people (M = 60.08, SD = 9.61) from Porto Alegre and metropolitan area, comprising 87 post-stroke patients and 66 healthy individuals. Three-way ANOVAs were used to assess main effects and interactions between the variables group (clinical/control), age and education. An influence of group and age on scores in the TRIACOG was found. We emphasize the relevance of these results to the selection of cut-off points for the tasks and cognitive functions assessed by the instrument, considering education and age, so as to allow more accurate identification of deficits in post-stroke patients.

Verbal fluency difficulties in aphasia: A combination of lexical and executive control deficits

BACKGROUND

Verbal fluency tasks are routinely used in clinical assessment and research studies of aphasia. People with aphasia produce fewer items in verbal fluency tasks. It remains unclear if their output is limited solely by their lexical difficulties and/or has a basis in their executive control abilities. Recent research has illustrated that detailed characterization of verbal fluency performance using temporal characteristics of words retrieved, clustering and switching, and pause durations, along with separate measures of executive control stands to inform our understanding of the lexical and cognitive underpinnings of verbal fluency in aphasia.

AIMS

To determine the locus of the verbal fluency difficulties in aphasia, we compared semantic and letter fluency trials between people with aphasia and healthy control participants using a wide range of variables to capture the performance between the two groups. The groups were also tested on separate measures of executive control to determine the relationship amongst these tasks and fluency performance.

METHODS & PROCEDURES

Semantic (animal) and letter (F, A, S) fluency data for 60s trials were collected from 14 people with aphasia (PWA) and 24 healthy adult controls (HC). Variables, such as number of correct responses, clustering and switching analyses, were performed along with temporal measures of the retrieved words (response latencies) and pause durations. Participants performed executive control tasks to measure inhibitory control, mental-set shifting and memory span.

OUTCOMES & RESULTS

Compared with HC, PWA produced fewer correct responses, showed greater difficulty with the letter fluency condition, were slower in getting started with the trials, showed slower retrieval times as noted in within- and between-cluster pause durations, and switched less often. Despite these retrieval difficulties, PWA showed a similar decline in the rate of recall to HC, and had similar cluster size. Executive control measures correlated primarily with the letter fluency variables: mostly for PWA and in one instance for HC.

CONCLUSIONS & IMPLICATIONS

Poorer performance for PWA is a combination of difficulties in both the lexical and executive components of the verbal fluency task. Our findings highlight the importance of detailed characterization of fluency performance in deciphering the underlying mechanism of retrieval difficulties in aphasia, and illustrate the importance of using letter fluency trials to tap into executive control processes.

WHAT THIS PAPER ADDS

What is already known on the subject PWA typically show impaired performance in verbal fluency tasks. It is debated whether this impaired performance is a result of their lexical difficulties or executive control difficulties, or a combination of both. This debate continues because previous studies have mostly used semantic fluency condition without including letter fluency condition; used a limited range of variables (e.g., number of correct responses); and not included separate executive control measures to explain the performance pattern in aphasia. This research addresses these outstanding issues to determine the specific contribution of lexical and executive control processes in verbal fluency in aphasia by including: both semantic and letter fluency conditions; a wide range of variables to identify the relative contribution of lexical and executive control mechanisms; and independent measures of executive control. What this paper adds to existing knowledge Using the multidimensional analysis approach for verbal fluency performance from both semantic and letter fluency conditions, this is the first study to systematically demonstrate that PWA had difficulties in both lexical and executive control components of the task. At the individual level, PWA had greater difficulty on the letter fluency condition compared with semantic fluency. We observed significant correlations between the executive control measures and verbal fluency measures primarily for the letter fluency condition. This research makes a significant contribution to our understanding of lexical and executive control aspects in word production in aphasia. What are the potential or actual clinical implications of this work? From a clinical perspective, this research highlights the importance of using a full range of verbal fluency and executive control measures to tap into the lexical as well as executive control abilities of PWA, and also the utility of using letter fluency to tap into the executive control processes in PWA.

Concurrent Validity and Reliability of the Core Lexicon Measure as a Measure of Word Retrieval Ability in Aphasia Narratives

Purpose General agreement exists in the literature that clinicians struggle with quantifying discourse-level performance in clinical settings. Core lexicon analysis has gained recent attention as an alternative tool that may address difficulties that clinicians face. Although previous studies have demonstrated that core lexicon measures are an efficient means of assessing discourse in persons with aphasia (PWAs), the psychometric properties of core lexicon measures have yet to be investigated. The purpose of this study was (a) to examine the concurrent validity by using microlinguistic and macrolinguistic measures and (b) to demonstrate interrater reliability without transcription by raters with minimal training. Method Eleven language samples collected from PWAs were used in this study. Concurrent validity was assessed by correlating performance on the core lexicon measure with microlinguistic and macrolinguistic measures. For interrater reliability, 4 raters used the core lexicon checklists to score audio-recorded discourse samples from 10 PWAs. Results The core lexicon measures significantly correlated with microlinguistic and macrolinguistic measures. Acceptable interrater reliability was obtained among the 4 raters. Conclusions Core lexicon analysis is potentially useful for measuring word retrieval impairments at the discourse level. It may also be a feasible solution because it reduces the amount of preparatory work for discourse assessment.

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.

Semantic fluency in aphasia: clustering and switching in the course of 1 minute

BACKGROUND

Verbal fluency tasks are included in a broad range of aphasia assessments. It is well documented that people with aphasia (PWA) produce fewer items in these tasks. Successful performance on verbal fluency relies on the integrity of both linguistic and executive control abilities. It remains unclear if limited output in aphasia is solely due to their lexical retrieval difficulties or has a basis in their executive control abilities. Analysis techniques, such as temporal characteristics of word retrieved, clustering and switching, are better positioned to inform the debate surrounding the lexical and/or executive control contribution for success in verbal fluency.

AIMS

To investigate the differences in quantitative (i.e., number of correct words) and qualitative (i.e., switching, clustering and word-retrieval times) performances on animal fluency task as a function of time between PWA and healthy control speakers (CS).

METHODS & PROCEDURES

Animal fluency data for 60 s were collected from 34 PWA and 34 CS, and responses were time stamped. The 60-s period was divided into four equal intervals of 15 s each (i.e., 15, 30, 45 and 60 s). The number of correct words, cluster size, number of switches, within-cluster pause and between-cluster pause were evaluated as a function of four 15-s time intervals between PWA and CS.

OUTCOMES & RESULTS

Compared with CS, PWA produced fewer words, had smaller cluster sizes and switched a fewer number of times. A decrease in the number of switches correlated with an increase in between-cluster pause durations. PWA showed longer within- and between-cluster pauses than CS. The two groups showed specific differences in the temporal pattern of the responses: as time evolved both PWA and CS showed decreased productivity for the number of correct words, but PWA reached the asymptote earlier in the time course than CS, neither group showed a change in cluster size, and the number of switches decreased as a function of time only for CS.

CONCLUSIONS & IMPLICATIONS

The findings suggest that for PWA the search and retrieval process is less productive and more effortful. This is indicated by smaller cluster size, fewer switches associated with increased between-cluster pause durations, as well as overall slowed retrieval times for the words. This shows that the difficulties with verbal fluency performance in aphasia have a strong basis in their lexical retrieval processes, as well as some difficulties in the executive component of the task.

Phonemic verbal fluency task in adults with high-level literacy

OBJECTIVE:

To establish normative parameters for the F-A-S form of the phonemic verbal fluency test, in a population of Brazilian Portuguese speaking adults with high-level literacy.

METHODS:

The sample comprised 40 male and female volunteers aged 19 to 59 years, and at least 8 years of formal education. Volunteers were first submitted to the Mini-Mental State Examination and the Clock Drawing cognitive screening tests, then to the F-A-S Verbal Phonemic Fluency Test; in this test, examinees were given 60 seconds to generate as many words as possible beginning with each of the three test letters.

RESULTS:

The means for number of words beginning the letters F, A and S and for total number of words beginning with either letter generated per minute corresponded to 15.3, 14.4, 13.9 and 43.5, respectively.

CONCLUSION:

Reference values obtained from young adults with high levels of literacy submitted to the F-A-S Verbal Phonemic Fluency Test in this study were similar to those reported in the international literature. These reference values can be used for clinical assessment of language disorder and neuropsychological evaluation.

OBJETIVO:

Obter parâmetros de normalidade na tarefa de fluência verbal fonêmica, versão F-A-S, em uma população de alto letramento de adultos falantes do português brasileiro.

MÉTODOS:

A amostra foi constituída por 40 voluntários, de ambos os sexos, com idade entre 19 e 59 anos, e com mais de 8 anos de estudo. Todos os voluntários foram inicialmente submetidos ao Miniexame do Estado Mental e ao Teste do Desenho do Relógio, para fins de rastreio cognitivo, e, então, ao Teste de Fluência Verbal Fonêmica F-A-S. Neste último, os indivíduos foram orientados a produzirem o maior número de palavras que conseguissem, iniciadas com cada uma das três letras ditas pelo examinador, em um intervalo de 60 segundos cada.

RESULTADOS:

As médias das palavras produzidas com as letras F-A-S foram as seguintes: "F" = 15,3 palavras por minuto; "A" = 14,4 palavras por minuto; e "S" = 13,9 palavras por minuto. A média do total de palavras emitidas iniciada com todas as letras do teste foi de 43,5 palavras.

CONCLUSÃO:

Foram obtidos valores de referência para o Teste de Fluência Verbal Fonêmica F-A-S para indivíduos adultos jovens de alto grau de letramento semelhantes aos de estudos internacionais. Tais valores podem ser utilizados na avaliação clínica de transtornos da linguagem e na avaliação neuropsicológica.

Verbal fluency in Alzheimer's disease and Aphasia

This study examined the impact of two neurological diseases on access to semantic knowledge and the status of semantic representations. Patients with Alzheimer's disease (AD) and Aphasia (APH) were compared with control groups using the supermarket fluency task. We measured several aspects: number of category names produced, number of categories sampled to produce the words, the number of words per category sampled, number of exemplars and kinds of errors recorded. Both AD and APH groups produced significantly fewer words on the fluency task than control groups. As compared with the APH and control groups, in the AD group verbal fluency was characterized by a tendency to generate more category names with fewer exemplars within a category. The findings are consistent with the view that a bottom-up disruption in semantic knowledge occurs in AD and a general semantic disruption occurs in Aphasia.

Recommendations for the use of common outcome measures in traumatic brain injury research

This article summarizes the selection of outcome measures by the interagency Traumatic Brain Injury (TBI) Outcomes Workgroup to address primary clinical research objectives, including documentation of the natural course of recovery from TBI, prediction of later outcome, measurement of treatment effects, and comparison of outcomes across studies. Consistent with other Common Data Elements Workgroups, the TBI Outcomes Workgroup adopted the standard 3-tier system in its selection of measures. In the first tier, core measures included valid, robust, and widely applicable outcome measures with proven utility in TBI from each identified domain, including global level of function, neuropsychological impairment, psychological status, TBI-related symptoms, executive functions, cognitive and physical activity limitations, social role participation, and perceived health-related quality of life. In the second tier, supplemental measures were recommended for consideration in TBI research focusing on specific topics or populations. In the third tier, emerging measures included important instruments currently under development, in the process of validation, or nearing the point of published findings that have significant potential to be superior to some older ("legacy") measures in the core and supplemental lists and may eventually replace them as evidence for their utility emerges.

Normative data for healthy elderly on the phonemic verbal fluency task - FAS

Phonemic verbal fluency tests assess the production of words beginning with specific letters. Of these letters, the most frequently used are F, A and S. It is a sensitive test for assessing frontal lobe functions.

Objective

To provide normative data for the elderly Brazilian population on the FAS test and to investigate the effects of age and schooling on test performance.

Methods

The individuals were divided into three age groups (60-69, 70-79 and =80 years), and into four groups according to education (1-3, 4-7, 8-11 and 12 years). All subjects were assessed by the Mini Mental State Examination and the FAS. Data were analyzed with Student's t test, ANOVA, simple linear regression and Spearman's correlation.

Results

We evaluated 345 cognitively healthy volunteers, 66.66% being female, aged 60 to 93 years, with an educational level ranging from one to 24 years. The average (number of items) ±SD for the whole sample was 28.28±11.53. No significant effect of gender was observed (p=0.5). Performance on the MMSE and education exerted a direct influence on FAS scores (p<0.001), with education being the most significant factor. A positive correlation was found between FAS and the MMSE (r=0.404; p<0.001).

Conclusion

The performance of Brazilian elderly on the phonemic verbal fluency tests-FAS is significantly influenced by education, where individuals with higher educational level present better performance than those with fewer years of schooling. Age and gender did not prove significant with the FAS.