Differential Performance on Noun- and Verb-Verbal Fluency Tasks in People with Aphasia

Introducción.Las tareas de fluidez fonológica y semántica son de uso frecuente en la evaluación neuropsicológica por su fácil aplicación y buena sensibilidad al deterioro cognitivo. En Argentina es limitado el cuerpo de evidencia psicométrica para dichas tareas, con especial desconocimiento de la estabilidad temporal de sus medidas. La producción psicométrica es aún menor para la variante fluidez de acción (emisión de verbos en infinitivo en un minuto). En efecto, este estudio analiza la fiabilidad test-retest de tres tareas de fluidez en adultos argentinos.Sujetos y métodos.La muestra se compuso de 85 argentinos (medida de edad, 63,7) de población general no clínica, un 75,3% mujeres, de nivel de instrucción medio-alto. Se efectuó un diseño longitudinal-prospectivo administrando tareas de fluidez fonológica, semántica y de acción en dos momentos distintos con un intervalo hasta de cuatro meses. Se analizó el coeficiente de correlación intraclase (CCI), método estadístico sugerido para estudios de fiabilidad test-retest. Para interpretar el CCI se adoptaron los criterios de Fleiss.Resultados.Las tareas de fluidez fonológica y semántica demostraron buena fiabilidad, con un CCI de 0,77 y 0,79. La fluidez de acción obtuvo excelente fiabilidad, con un CCI de 0,9.Conclusión.Las tareas de fluidez relevadas poseen apropiada estabilidad temporal, por lo que se sugiere su uso en investigaciones neuropsicológicas prospectivas (cuando se evalúe el lenguaje en distintos momentos) o cuando se requiera un seguimiento de la evolución de pacientes afásicos en neurorrehabilitación. Basándose en su excelente fiabilidad, se recomienda utilizar con más frecuencia la variante de acción.

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. 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). 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. 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. 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.

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.

Although evidence has indicated that subjective cognitive decline (SCD) may be an early sign of Alzheimer's disease (AD), the objectification of cognitive impairment in SCD is challenging, mainly due to the lack of sensitivity in assessment tools. The present study investigated the potential contribution of two verbal fluency tasks with high executive processing loads to the identification of cognitive impairment in SCD. A total of 60 adults with SCD and 60 healthy controls (HCs) performed one free action (verb) fluency task and two fluency tasks with more executive processing load-an alternating fluency task and an orthographic constraint fluency task-and the results were compared. In the free action fluency task, the performance of the participants with SCD and the HCs was similar. However, HCs performed significantly better than SCD in the alternating fluency task, which required mental flexibility, and the orthographic constraint fluency task, which required inhibition. The study findings suggest that verbal fluency tasks with high executive processing load could be useful in detecting cognitive deficits at the preclinical stage of AD. The inclusion of such tests in assessment batteries should be considered in order to improve the detection of subtle cognitive impairment in preclinical major neurocognitive disorder populations.

The objective of the present study was to establish whether performance in an action fluency task is of value in the differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). After collecting normative data on performance in an action fluency task and a conventional animal fluency task in a cohort of French-speaking healthy controls, we assessed AD and DLB patients. Only the action fluency score differed significantly between the two demented groups, with DLB patients performing worse than AD patients. However, a composite action and animal fluency score was found to be more effective for discriminating between these two groups.

Inspired by the hypothesized neural dissociation between the retrieval of nouns and verbs, several studies now support the construct validity of Action (verb) Fluency as a measure of frontostriatal systems function. Relative to traditional noun- and letter-cued verbal fluency tests, Action Fluency is more sensitive to HIV-1-associated neuropsychological impairment, which may reflect inefficiencies engaging motor representations during action retrieval in this population. Accordingly, impaired Action Fluency might adversely impact instrumental activities of daily living (IADL) by disrupting the production and organization of script-based action schemas upon which successful IADL performance depends. The present study thus sought to evaluate the ecological validity of Action Fluency as a predictor of IADL among persons with HIV-1 infection. Action, Letter (FAS), and Noun (animal) fluency were compared in 21 HIV-1-infected participants with self-reported IADL dependence relative to 76 demographically comparable HIV-1-infected participants who reported no IADL declines. Results revealed significant between-group differences in Action and Letter Fluency, but not Noun Fluency. Action Fluency achieved an overall hit rate of 76% and was more sensitive than Letter Fluency in classifying IADL dependent participants. Individuals with impaired Action Fluency performance had a fivefold risk of concurrent IADL dependence as compared to those who performed within normal limits. Findings suggest that Action Fluency may possess incremental ecological validity in the identification of HIV-1-associated neurocognitive disorders. The HNRC is supported by Center award MH 62512 from the National Institute of Mental Health. The research described was also supported by grants DA12065 and MH59745 from the National Institutes of Health. Note that, the views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, nor the United States Government. The authors thank Jennifer Marquie Beck for her assistance with data coding.

Verbal fluency in Parkinson’s disease patients on/off dopamine medication

Action (verb) fluency is a newly developed verbal fluency task that requires the examinee to rapidly generate as many verbs (i.e., "things that people do") as possible within 1 min. Existing literature indicates that action fluency may be more sensitive to frontal-basal ganglia loop pathophysiology than traditional noun fluency tasks (e.g., animal fluency), which is consistent with the hypothesized neural dissociation between noun and verb retrieval. In the current study, a series of analyses were undertaken to examine the psychometric properties of action fluency in a sample of 174 younger healthy participants. The first set of analyses describes the development of demographically adjusted normative data for action fluency. Next, a group of hypothesis-driven correlational analyses reveals significant associations between action fluency and putative tests of executive functions, verbal working memory, verbal fluency, and information processing speed, but not between action fluency and tests of learning or constructional praxis. The final set of analyses demonstrates the test-retest stability of the action fluency test and provides standards for determining statistically reliable changes in performance. In sum, this study enhances the potential clinical applicability of action fluency by providing demographically adjusted normative data and demonstrating evidence for its reliability and construct validity.

Previous research suggests that lexical and semantic verbal fluency are differentially sensitive to the effects of cortical and subcortical dementias, but little is known about action fluency performance in dementias. The present study compared lexical, semantic, and action fluency in groups of patients with Parkinson's disease (PD) with and without dementia and an elderly control group. Findings revealed an interaction between fluency type and subject group. Although the demented PD (PDD) group performed significantly more poorly than their non-demented counterparts and normal controls on all three fluency tasks, a disproportionate disparity in scores was noted on the action fluency task. The findings suggest that action fluency may be particularly sensitive to PD-associated dementia and may be an early indicator of the conversion from PD to PDD. As reported elsewhere, PD without dementia was not associated with significant impairment on any of the fluency tasks.

Action verbal fluency: Normative data for the elderly

Action (verb naming) fluency as an executive function measure: convergent and divergent evidence of validity

A gamma band specific role of the subthalamic nucleus in switching during verbal fluency tasks in Parkinson’s disease

Semantic and verbal fluency tasks are widely used as a measure of frontal capacities. It has been well described in literature that patients affected by schizophrenic and bipolar disorders present a worse execution in these tasks. Some authors have also noted the importance of educational years. Our objective is to analyze whether the effect of cognitive malfunction caused by apathology is superior to the expected effect of years of education in phonemic verbal fluency (PVF) and semantic verbal fluency (SVF) task execution.A total of 62 individuals took part in this study, out of which 23 were patients with schizophrenic paranoid disorder, 11 suffered from bipolar disorder with psychotic symptomatology, 13 suffered from bipolar disorder without psychotic symptomatology, and 15 participants were nonpathological individuals. All participants were evaluated with the PVF and SVF tests (animals and tools). The performance/execution results were analyzed with a mixed-model ANCOVA, with educational years as a covariable.The effect of education seems to be more determined by PVF FAS tests than by SVF. With PVF FAS tasks, the expected effect of pathology disappears when the covariable EDUCATION is introduced. With SVF tasks, the effect continues to be significant, even though the EDUACTION covariable dims such effect.These results suggest that SVF tests (animals category) are better evaluation tools as they are less dependent on the patients’ education than PVF FAS tests.

Verb naming fluency in hypokinetic and hyperkinetic movement disorders

Action verbal fluency normative data for the elderly