Clustering and Switching Patterns in Semantic Fluency and Their Relationship to Working Memory in Mild Cognitive Impairment

BACKGROUND AND PURPOSE: Semantic verbal fluency test is a neuropsychological assessment that can sensitively detect neuropathological changes. Considering its multifactorial features tapping various cognitive domains such as semantic memory, executive function, and working memory, it is necessary to examine verbal fluency performance in association with underlying cognitive functions. The objective of the current study was to investigate semantic fluency patterns of people with mild cognitive impairment (MCI) based on clustering and switching and their relationship with working memory. METHODS: Twenty-six individuals with MCI and 23 normal elderly adults participated in this study. A semantic verbal fluency test (animal version) was administered and the performance was analyzed using the following measures: number of correct words, cluster size, and number of switches. Scores of digit forward (DF) and backward span tasks were employed as working memory measures. RESULTS: Analyses of variance revealed significant group differences in the numbers of correct words and switches. Multivariate logistic regression and receiver-operating characteristic analyses showed that the number of switches more sensitively distinguished MCI existence than the number of correct words. Stepwise linear regression analysis showed that DF task and age significantly predicted the number of correct words while only the DF task significantly predicted the number of switches. CONCLUSIONS: Decrement in semantic verbal fluency in MCI seems to be associated with impaired switching abilities. Working memory capacity might serve as the underlying cognitive factor related to decreased verbal fluency in MCI.

Patrones de correlación de fluencias semánticas y fonológicas en niños en edad escolar / Correlational Patterns in Semantic and Phonological Fluency in School Aged Children

Resumen Las tareas de fluidez verbal semántica (FVS) y fluidez verbal fonológica (FVF) son medidas sensibles para detectar y diagnosticar diversas patologías tanto en la población adulta como en la infantil. Dado que las tareas de FVS y FVF permiten detectar problemas específicos de determinadas facultades lingüísticas o cognitivas, el objetivo de este trabajo es indagar las posibles relaciones existentes entre FVS y FVF en una población de niños argentinos de nivel escolar primario de 3°, 5° y 7° grado y edades comprendidas entre los 8 y 12 años. Los 86 niños participantes respondieron a una tarea de FVS en la que se evaluaron cinco categorías (animales, partes del cuerpo, medios de transportes, ropa e instrumentos musicales) y una tarea de FVF en la que respondieron a los fonemas /f/, /a/, /s/. Se realizó un análisis de correlaciones cuyo resultado muestra que existe una asociación de mediana intensidad entre ambas tareas. Además, se llevaron a cabo un análisis factorial exploratorio y uno confirmatorio, que detectaron dos factores diferenciados: un factor verbal semántico y un factor verbal fonológico. Los resultados obtenidos muestran que los procesos fonológicos y semánticos se encuentran diferenciados desde edades tempranas, aunque por su correlación es posible concluir que ambos procesos confluyen en un mismo almacén de búsqueda en la memoria verbal.

Abstract Semantic verbal fluency tasks (SVF) and phonological verbal fluency tasks (PVF) are highly sensitive measures used to detect and diagnose different pathologies in adult and child populations. The results of numerous investigations point out differential performances between these two tasks both in adults and children. Based on this evidence, we intend to identify the possible connections between SVF and PVF in a group of Argentinian children aged 8 to 12 years old who attended to 3rd, 5th and 7th school primary levels. Participants answered to a SVF task which tested five categories (animals and body parts for living things and transports, cloth and musical instruments for inanimate objects domain) and a PVF task where the phonemes /f, a, s/ were assessed. A correlations analysis was carried out. The result showed there is a mild association between both tasks. In addition, an exploratory factor analysis and a confirmatory factor analysis were conducted. Two differential factors were detected: a semantic verbal factor and a phonological verbal factor. Our results show that phonological and semantic are different processes and function separately in early development, although due to their correlation it is possible to conclude that both processes converge in the same store in verbal memory.

Fluidez verbal semántica y fonológica en una muestra de niños de Argentina / Fluência semântica e fonológica em uma amostra de crianças Argentinas / Phonological and semantic verbal fluency tasks in a sample of Argentinean children

El objetivo del presente trabajo es obtener información del patrón evolutivo de desempeño en tareas de fluidez verbal para una muestra de niños argentinos de nivel primario de 3°, 5° y 7° grado. Se evaluó a los participantes con una tarea de fluidez semántica, en la que se evaluaron las categorías de animales, frutas y verduras, y partes del cuerpo para el dominio de seres vivos, y medios de transporte, instrumentos musicales y ropa para el de objetos inanimados. Asimismo fueron evaluados con una tarea de fluidez fonológica en la que se testearon los fonemas /f/, /a/ y /s/. Los datos obtenidos dan cuenta de diferencias de rendimiento entre las tareas de fluidez con un mejor desempeño en las tareas de fluidez semántica. Asimismo, en las tareas de fluidez semántica se observa un mejor rendimiento en el dominio de seres vivos. Las diferencias obtenidas en ambas tareas se identifican al comparar los grupos según escolaridad, siendo únicamente los niños de 3° grado los que, con menor cantidad de ejemplares recuperados, se disocian significativamente de los de 5° y 7° grado. Estos hallazgos son discutidos a la luz de posibles diferencias en función del desarrollo cognitivo, de las funciones ejecutivas y del sistema semántico.

No presente trabalho oferecemos dados de tarefas de fluência verbal para crianças argentinas de 3°, 5° e 7 ° ano do ensino fundamental. Os participantes foram avaliados com uma tarefa de fluência semântica, que testou as categorias de animais, frutas e legumes e partes do corpo para o domínio dos seres vivos e meios de transporte, instrumentos musicais e roupas para os objetos inanimados. As crianças também foram avaliadas com uma tarefa de fluência fonológica que testou os fonemas /f/, /a/ e /s/. Os dados obtidos apontam para diferenças de desempenho entre as tarefas e mostraram um melhor desempenho nas de fluência semântica. Além disso, nas tarefas de fluência semântica os participantes tiveram um melhor desempenho no domínio dos seres vivos. Tanto para fluência semântica quanto fonológica, as diferenças estiveram presentes quando os grupos foram comparados pelo nível de escolaridade, de modo que os alunos de 3° ano se dissociam significativamente dos 5° e 7 ° anos, produzindo menor quantidade de exemplares. Os resultados são discutidos à luz de possíveis diferenças originadas no desenvolvimento cognitivo, as funções executivas e o sistema semântico.

The aim of this work is to obtain data about the evolutionary pattern of performance in verbal fluency tasks for a sample of Argentinean primary school aged children (3rd, 5th y 7th grade) in semantic and phonological verbal fluency tasks. For the semantic fluency task, children were assessed in different categories: animals, fruits and vegetables, and body parts for living things domain, and means of transport, musical instruments and clothes for inanimate objects. For the phonological fluency assessment, children were tested with /f/, /a/and /s/phonemes. Both fluency tasks showed differences between grades, indicating the influence of education. Besides, irrespective of the grade, children performed better on the semantic fluency tasks. Results in the semantic fluency task also showed a better performance for the living things domain over the inanimate objects domain. Further analysis on the results showed that 3rd grade children have the worst performance, compared to 5th and 7th grade children. The results of our work are discussed taking in account cognitive mechanisms, executive functions and semantic memory development.

The Difference of Verbal Fluency Task Performance between Alzheimer's Disease and Subcortical Vascular Dementia: CREDOS (Clinical Research Center for Dementia of South Korea) Study

BACKGROUND: The verbal fluency test consists of two separate tests of semantic fluency and phonemic fluency. The performance patterns of these tests differ with the type of dementia. We studied the patterns of verbal fluency between Alzheimer's disease (AD) and subcortical vascular dementia (SVaD), and assessed the clinical utility of these tests. METHODS: The 1,475 selected participants comprised 73 normal control subjects, 673 patients with amnestic mild cognitive impairment (aMCI), 535 AD patients, 42 patients with subcortical vascular mild cognitive impairment (svMCI), and 152 SVaD patients. We analyzed the z-score for the total number of animal items as a semantic fluency index and the z-score of the phonemic total score as a phonemic fluency index. RESULTS: The performance of semantic fluency was lower than that of phonemic fluency in all groups. The SVaD group showed the worst scores and abnormal performances on both tests, while the AD group presented abnormal performance only for semantic fluency. Dividing the patients with dementia according to severity revealed a different pattern between AD and SVaD for the clinical dementia rating (CDR) stage of 0.5. The performance of the AD group declined gradually with CDR. However, the SVaD group performed very poorly in both tests even for very mild dementia (CDR stage of 0.5). The aMCI and svMCI groups exhibited similar performance patterns. CONCLUSIONS: The pattern of semantic and phonemic fluency was not clinically useful at the MCI stage, but it could be helpful in differentiating AD and SVaD in the early stage of dementia.

Usefulness of Verbal Fluency Performance as Follow-up Screening Tool in Patients With Mild to Moderate Alzheimer's Disease

BACKGROUND: Impaired verbal fluency in Alzheimer's disease (AD) has been well documented. Furthermore, crosssectional studies suggest that semantic fluency is disproportionately impaired relative to phonemic fluency in AD. The aim of this study was to determine the ability of fluency measures as follow-up screening tool for mild to moderate AD. METHODS: Participants were recruited from AD patients in mild to moderate stages. We annually evaluated semantic (animal, supermarket) and phonemic (giyeok, siot, ieung) fluency and tested other extensive neuropsychological measures for two years. RESULTS: A total of 33 AD patients were included at baseline and 1-year follow-up, who were aged 70.18+/-5.97 years at baseline. Eleven patients completed a 2-year follow-up. Phonemic fluency total score was not significantly changed during the study period. However, semantic fluency total score tended to decline annually, and significantly declined at 2-year follow-up compared to baseline. In addition, difference score (semantic fluency minus phonemic fluency) was significantly decreased at every follow-up compared to previous year. In Pearson correlation analyses between changes of verbal fluency and other neuropsychological measures, changes of semantic fluency appeared to be significantly correlated with neuropsychological measures much more than changes of phonemic fluency. CONCLUSIONS: Significant longitudinal declines in semantic fluency compared to phonemic fluency seem to be consistent with previous cross-sectional studies. These patterns of changes in verbal fluency were observed even at an interval of one year follow-up in our study. The verbal fluency might be useful follow-up screening test for mild to moderate AD in the memory clinic setting.