Analysis of sociodemographic and linguistic influences on verbal fluency performance in Basque and Catalan bilingual adults

BackgroundVerbal 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.AimsTo 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 & ProceduresSemantic (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 & ResultsCompared 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 & ImplicationsPoorer 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 ADDSWhat is already known on the subjectPWA 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 knowledgeUsing 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.

Most studies of dyslexia focus on domains of impairment (e.g., reading and phonology, among others), but few examine possible strengths. In the present study, we investigated semantic fluency as a cognitive strength in English-speaking children with dyslexia aged 8-13. Ninety-seven children with dyslexia completed tests of letter and semantic verbal fluency, standardized measures of reading and cognitive functions, and task-free resting-state functional magnetic resonance imaging (rs-fMRI). First, we adjusted performance on semantic fluency by letter fluency and created a residual score that was used to separate participants into high (residual >0) or average (residual <0) semantic performance groups. We then employed a psycholinguistic clustering and switching approach to the semantic fluency task and performed dynamic task-free rs-fMRI connectivity analysis to reveal group differences in brain dynamics. High and average semantic fluency groups were well-matched on demographics and letter fluency but differed on their psycholinguistic patterns on the semantic fluency task. The high semantic fluency group, compared to the average semantic fluency group, produced a higher number of words within each cluster, a higher max cluster size, and a higher number of switches. Differential dynamic rs-fMRI connectivity (shorter average dwell time and greater brain state switches) was observed between the high and average groups in a large-scale bilateral frontal-temporal-occipital network. These data demonstrate that a subgroup of children with dyslexia perform above average on semantic fluency tasks and their performance is strongly linked to distinct psycholinguistic patterns and differences in a task-free resting-state brain network, which includes regions previously implicated in semantic processing. This work highlights that inter-individual differences should be taken into account in dyslexia and reveals a cognitive area of strength for some children with dyslexia that could be leveraged for reading interventions.

To compare longitudinal verbal fluency performance among Latinx Spanish speakers who develop Alzheimer's disease to those who do not develop dementia in absolute number of words produced on each task and their ratio to combine both scores. Participants included 833 Latinx Spanish-speaking older adults from a community-based prospective cohort in Manhattan. We performed growth curve modeling to investigate the trajectories of letter and semantic fluency, and their ratio (i.e., 'semantic index'), between individuals who developed Alzheimer's disease and those who did not (i.e., controls). The semantic index quantifies the proportion of words generated for semantic fluency in relation to the total verbal fluency performance. Letter fluency performance did not decline in controls; we observed a linear decline in those who developed Alzheimer's disease. Semantic fluency declined in both groups and showed an increased rate of change over time in the incident Alzheimer's disease group; in comparison, the control group had a linear and slower decline. There were no group differences in the longitudinal trajectory (intercept and slope) of the semantic index. A decline in letter fluency and a more rapid and accelerating decline over time in semantic fluency distinguished people who developed Alzheimer's disease from controls. Using the semantic index was not a superior marker of incident Alzheimer's disease compared to examining the two fluency scores individually. Results suggest the differential decline in verbal fluency tasks, when evaluated appropriately, may be useful for early identification of Alzheimer's disease in Latinx Spanish speakers, a historically understudied population.

Verbal fluency (VF) is an informative cognitive task. Lesion and functional imaging studies implicate distinct cerebral areas that support letter versus semantic fluency and the understanding of neural and cognitive mechanisms underlying task performance. Most lesion studies include chronic stroke patients. People with primary progressive aphasia (PPA) provide complementary evidence for lesion-deficit associations, as different brain areas are affected in stroke versus PPA. In the present study we sought to determine imaging, clinical and demographic correlates of VF in PPA. Thirty-five patients with PPA underwent an assessment with letter and category VF tasks, evaluation of clinical features and an MRI scan for volumetric analysis. We used stepwise regression models to determine which brain areas are associated with VF performance while acknowledging the independent contribution of clinical and demographic factors. Letter fluency was predominantly associated with language severity (R2 = 38%), and correlated with the volume of the left superior temporal regions (R2 = 12%) and the right dorsolateral prefrontal area (R2 = 5%). Semantic fluency was predominantly associated with dementia severity (R2 = 47%) and correlated with the volume of the left inferior temporal gyrus (R2 = 7%). No other variables were significantly associated with performance in the two VF tasks. We concluded that, independently of disease severity, letter fluency is significantly associated with the volume of frontal and temporal areas whereas semantic fluency is associated mainly with the volume of temporal areas. Furthermore, our findings indicated that clinical severity plays a critical role in explaining VF performance in PPA, compared to the other clinical and demographic factors.

Introduction:Verbal fluency is a cognitive function that can be easily assessed at the bedside and provide valuable data for clinical assessment of various cognitive functions. We decided to provide a standardized test to assess verbal fluency in the Persian language, including both phonemic and semantic fluency subtests.Methods:First, three phonemes (/p/, /d/, and /ʃ/) and three categories (animals, fruits, and kitchen appliances) were selected based on a pilot study and a panel of specialists. Then, we selected 500 Persian-speaking participants (47.8% male) aged 18 to 65 years via a convenient sampling method from the general population. Participants were grouped according to age, gender, and education. They performed the verbal fluency test.Results:The Mean±SD number of generated words in letter fluency and semantic fluency was 8.3±4.1 and 18.0±5.5, respectively. Age, educational level, and mother tongue were associated with letter fluency. Semantic fluency was associated with age, gender, education level, and mother tongue.Conclusion:For a more reliable clinical assessment, we suggest using all three letters (phonemes) and three semantic categories for each subject, calculating the mean of the produced words, and comparing them with the suggested cut-off points provided for each subcategory. Age was negatively correlated with the number of generated words in letter fluency (r=−0.33; P<0.001) and semantic fluency tasks (r=−0.26; P<0.001). In the letter fluency task, there was no statistically significant difference between males and females according to the number of generated words (P=0.057). However, in semantic fluency, female participants generated more words (P=0.005). Mother tongue (Farsi) showed a significant effect both on letter fluency (t=5.55, P<0.001) and semantic fluency (t=9.41, P<0.001). Level of education had a significant association with both letter fluency (F=117.23, P<0.001) and semantic fluency (F=64.48, P<0.001).HighlightsThe study subjects generated 8.3±4.1 words in one minute in the letter fluency test.Letter fluency was associated with educational level and mother tongue.The Mean±SD number of generated words in semantic fluency (18±5.5) was higher than letter fluency.Semantic fluency was associated with age, gender, education level, and mother tongue.Plain Language SummaryPractitioners use neuropsychological tests to diagnose mental problems. Verbal fluency is a test in which participants have to generate as many words as possible from a specified category in a given time. This category can be phonemic (letter), which means words beginning with a specified letter or semantic, including objects such as animals or fruits. The number of words produced by participants is essential, and if it is fewer than normal, it shows psychological or neurological conditions such as Alzheimer disease. The norms are variable in different languages, cultures, and educational levels. We found that the Mean±SD numbers of generated words in letter fluency and semantic fluency were 8.3±4.1 and 18.0±5.5, respectively. These values can be used for neuropsychological testing in the Iranian population.

Event Abstract Back to Event Verbal fluency performance in Bengali-English bilingual aphasia Abhijeet Patra1 and Arpita Bose1* 1 University of Reading, School of Psychology and Clinical Language Sciences, United Kingdom Introduction: Research has shown that impairments in executive control may influence word production abilities in aphasia[1,2]. However, studies investigating the contribution of lexical retrieval and executive control processes during word production are mostly limited to monolingual aphasia[3,4]. Very little is known about bilinguals with aphasia (BWA). A better approach to understand the relationship between lexical retrieval and executive control processes might be to use a task that simultaneously draw upon these processes. In a verbal fluency task, lexical and executive contribution for semantic and letter fluency conditions are different; semantic fluency largely depends on lexical retrieval abilities, whilst letter fluency largely depends on executive control abilities. Characterisation of verbal fluency performance beyond number of correct responses (CR) (e.g., Fluency Difference Score FDS; cluster size; number of switches; temporal measures such as within- and between-cluster pauses), have enabled researchers to specifically speculate the components of performance that depends on lexical retrieval vs. executive control processes[5,6,7]. Previous research has shown that in semantic fluency, BWA produced fewer CR, smaller cluster sizes, and fewer number of switches compared to bilingual healthy adults (BHA)[5,6]. These studies have emphasised the greater role of lexical processes in performance differences between BWA and BHA. However, in absence of comparison to letter fluency, it remains inconclusive if it is only the lexical processes that are compromised in BWA. We compared semantic and letter fluency conditions between Bengali-English BWA and BHA to determine: a) if poor performance in aphasia is due to lexical retrieval and/or executive control difficulties; b) are the differences more exaggerated on measures which depend heavily on the executive control processes. Bengali is a South-Asian language spoken by 180.5 million speakers in the world[8]. Despite that aphasia research reporting Bengali speakers remain under-presented (only one study)[9]. We attempt to fill this gap in the literature. Methods & Procedure: Semantic (animals, fruits and vegetables) and letter fluency (/p/, /k/, /m/) 60-seconds trails were collected from eight non-fluent Bengali-English BWA and eight Bengali-English BHA in their dominant language (Bengali). The groups were matched for age, gender, years of education, and bilingualism measures (language proficiency, usage, dominance). We measured: CR, FDS ((CR.semantic fluency - CR.letter fluency)/CR.semantic fluency), cluster size, number of switches, within-and between-cluster pause. Results and Discussion: Table 1 presents results summary. Overall, on both fluency conditions, compared to BHA, BWA produced fewer number of CR, had higher FDS, made fewer switches, and had longer between-cluster pauses. These results are indicative of difficulty in the executive control component of the verbal fluency task in addition to their lexical difficulties[4,7]. Both groups performed similarly on cluster size and within-cluster pauses. Fewer number of CR, and fewer switches for BWA are consistent with the literature[5,6]. No difference in cluster size and within-cluster pause suggest similar search strategies used by BWA and BHA while accessing the mental lexicon. Our results demonstrate that inclusion of letter fluency and a full range of verbal fluency measures are necessary to understand the effect of lexical and executive control processes in verbal fluency performance. Acknowledgements We would like to thank all our participants for their time and effort. We also would like to acknowledge Felix trust, UK for the PhD fellowship.

To test the hypothesis that different neurocognitive networks underlie verbal fluency deficits in frontotemporal lobar degeneration (FTLD). Letter ("FAS") and semantic ("animal") fluency tests were administered to patients with a behavioral/dysexecutive disorder (bvFTLD; n = 71), semantic dementia (SemD; n = 21), and progressive nonfluent aphasia (PNFA; n = 26). Tests measuring working memory, naming/lexical retrieval, and semantic knowledge were also obtained. MRI voxel-based morphometry (VBM) studies were obtained on a subset of these patients (bvFTLD, n = 51; PNFA, n = 11; SemD, n = 10). Patients with SemD were disproportionately impaired on the semantic fluency measure. Reduced output on this test was correlated with impaired performance on naming/lexical retrieval tests. VBM analyses related reduced letter and semantic fluency to anterior and inferior left temporal lobe atrophy. Patients with bvFTLD were equally impaired on both fluency tests. Poor performance on both fluency tests was correlated with low scores on working memory and naming/lexical retrieval measures. In this group, MRI-VBM analyses related letter fluency to bilateral frontal atrophy and semantic fluency to left frontal/temporal atrophy. Patients with PNFA were also equally impaired on fluency tests. Reduced semantic fluency output was correlated with reduced performance on naming/lexical retrieval tests. MRI-VBM analyses related semantic fluency to the right frontal lobe and letter fluency to left temporal atrophy. Distinct neurocognitive networks underlie impaired performance on letter and semantic fluency tests in frontotemporal lobar degeneration subgroups.

Normative Data for two Verbal Fluency Tests in a Spanish-Speaking Adult Population Living in the U.S./México Border Region

Depression induced cognitive impairment, also referred to as the dementia syndrome of depression or pseudodementia, has been well characterized, yet the extent to which the more common mild depressive symptoms influence cognition has not been well studied. We sought to identify the influence of mild depressive symptoms on verbal fluency performance in a large sample of healthy community dwelling older adults. Letter and semantic fluency testing was conducted on 188 participants (ages 60-92 years) with no known history of neurologic or psychiatric disease. Depressive symptoms were assessed with the Geriatric Depression Scale (GDS). A total of 39 subjects obtained GDS scores consistent with mild depressive symptoms (GDS=10-19), and 149 subjects were identified as not depressed (GDS<10). ANOVA indicated that subjects with mild depressive symptoms performed significantly worse than normal controls on letter fluency (p <.05), but there was no significant difference between the groups on semantic fluency. Analysis of the nondepressed group stratified into young-old, middle-old, and oldest-old revealed a significant decline in semantic (p <.001) but not letter fluency with age. The nondepressed young-old showed the expected advantage for word list generation to semantic as compared to letter categories, yet this pattern was reversed in the older age groups, where letter fluency scores exceeded semantic fluency scores. Our results suggest that the presence of even mild depressive symptoms may confound using letter versus category discrepancies in the differential diagnosis of dementia. Further, our findings suggest that the commonly used strategy of examining letter-semantic fluency discrepancies may not be relevant for individuals of advanced age. Age-stratified normative data for fluency testing in older adults is also provided.

In Alzheimer’s dementia (AD), greater declines in semantic fluency (SF) relative to letter fluency (LF) have been assumed to reflect semantic disintegration. However, the same pattern is observed in typical aging and neurodegenerative disorders besides AD. We examined this assumption by comparing different aspects of SF and LF performance in older adults with and without dementia, and identifying which verbal fluency measures most clearly distinguish AD from typical aging. Verbal fluency data were compared from 109 individuals with AD and 66 typically aging adults. Correct items, clusters, and errors were analyzed using both raw counts and proportions. Regression analyses examined Task-by-Group interactions and the impact of demographic variables on verbal fluency measures. ROC analyses examined the sensitivity and specificity of the different outcome measures. In regressions, interactions were found for raw but not proportional data, indicating that different group patterns were driven largely by the number of correct items produced. Similarly, in ROC analyses, raw SF totals showed stronger discriminability between groups than either raw discrepancy scores (SF–LF) or discrepancy ratios (SF/LF). Age and cognitive status (MMSE) were the strongest individual predictors of performance. Findings suggest that AD entails quantitative declines in verbal fluency, but qualitatively similar patterns of performance relative to typically aging adults. Thus, SF declines in AD seem to be at least partially attributable to an exaggeration of the underlying mechanisms common to typical aging, and do not necessarily implicate semantic disintegration.

Amyloid pathology is associated with semantic loss in patients with subjective cognitive decline

Verbal fluency provides a unique index of the functional architecture of control functions because it reflects the interactions between executive processes and lower-level language processes. However, an evaluation of the number of correct words alone does not enable one to determine precisely which processes are impaired. This study investigates post-stroke fluency impairments, focusing on previously unexplored indices and their neuroanatomical correlates using voxel-based lesion symptom mapping (VLSM). In total, 337 patients and 851 controls performed letter and semantic fluency tests. Analyses included overall performance (correct responses) and strategic indices (errors, time course, frequency, switches, and cluster size). Stroke patients produced fewer correct responses, more rule-breaking errors, fewer words after 15″, fewer infrequent words, fewer switches, and smaller clusters in letter fluency. Switching was strongly associated with letter fluency, while clustering was more related to semantic fluency. VLSM identified left-hemisphere structures, particularly frontal tracts (e.g., anterior thalamic and frontostriatal tracts), associated with switching, and a smaller set of left-hemisphere structures linked to clustering. Conceptually, the findings suggest stroke-related fluency disorders primarily arise from impairments in executive strategic search, as indicated by switching impairments, with weaker impairment on lexicosemantic abilities. The rarity of rule-breaking and perseverative errors indicates that inhibition and working memory deficits do not significantly contribute to poor fluency. The patients' production of infrequent words and fluency worsened over time, although the precise contributions of the three core processes to these additional changes require further investigation. Our results highlight the importance of detailed fluency evaluations in stroke patients for optimized rehabilitation.

To evaluate the functional neuroanatomies underlying letter and category fluency, 18 normal controls were studied with oxygen-15 water regional cerebral blood flow positron emission tomography. Three counterbalanced conditions each consisted of 6 trials (45 s each): letter fluency (generating words when cued with a particular letter), semantic fluency (generating words when cued with a particular category), and a control condition (generating days of the week and months of the year). Relative to the control, participants activated similar brain regions during both fluency tasks, including the anterior cingulate, left prefrontal regions, thalamus, and cerebellum; reductions were found in parietal and temporal regions. In a direct comparison of the 2 fluency tasks, inferior frontal cortex and temporoparietal cortex (hypothesized to participate in a phonologic loop for accessing word pronunciation) were activated more during letter than semantic fluency, whereas left temporal cortex (associated with access to semantic storage) was activated more during semantic than letter fluency. This study identifies subtle differences in the neural networks underlying letter and semantic fluency that may underlie the dissociation of these abilities in patients.

The aim of this study was to examine the sensibility of NIRS in observation of brain activation during a verbal fluency test. Twenty-three participants were given letter fluency and semantic fluency tests and the hemodynamism was measured by NIRS. Thirty-three pairs of optodes were attached, so they can measure signals from 52 channels consisting of adjacent pairs of emitters and detectors. Results were investigated in terms of the change of blood flow volume value of OxyHb for word generation. The results showed a significant interaction between task (letter fluency and semantic fluency) and cortical area (prefrontal and temporal) in the analysis of variance. Here, the prefrontal area showed marked activation in the left hemisphere during letter fluency task, whereas the temporal area showed activation in the semantic fluency task performance. These findings by NIRS confirmed different cerebral functions between semantic and letter fluency tasks, which were coincident with the findings by previou...

Background: Alzheimer's disease (AD) is the most common type of dementia. Patients with AD have impaired semantic knowledge of nouns and verbs as well as the ability to verb retrieval. Objectives: The aim of this study was to compare verbal fluency and verb fluency and to investigate the association between severity and types of fluency (verbal-verb) in patients with AD. Patients and Methods: This cross-sectional study was performed on 30 patients (14 males, 16 females) with AD. The participants were assessed using the Mini Mental State Examination (MMSE) and a neurologist made the diagnosis of AD. In order to examine verb and verbal fluency, the subjects were asked to name any words that they remember in one minute. Scoring was based on the correct number of items and data analysis was performed by SPSS 16. Results: There was a significant positive correlation between letter fluency and verb fluency (P = 0.013), letter fluency and semantic fluency (P < 0.001), and verb fluency and semantic fluency (P = 0.002) in patients with AD. The results showed significant differences between letter fluency (P < 0.001), verb fluency (P = 0.034), and semantic fluency (P < 0.001) among patients with different severity of AD. In addition, the most frequently produced words in letter fluency were /a/, /s/, and /f/, consecutively. The mean ratio of semantic fluency to letter fluency was 3:5. Conclusions: In patients with AD, verb fluency was impaired more than semantic fluency was. Verb fluency task is an important criterion in diagnosis of early dementia. Therefore, the investigation of verb fluency in susceptible individuals with dementia might prevents the progression of the disorder.