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Clustering and switching analysis of verb fluency in individuals with Alzheimer’s disease

Análise de clustering e switching da fluência de verbos em indivíduos com doença de Alzheimer

Bárbara Costa Beber; Franceia Veiga Liedtke; Felipe Schroeder de Oliveira; Lucas Müller-Silveira; Emily Viega Alves; Márcia Lorena Fagundes Chaves; Jerusa Fumagalli de Salles

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To investigate verb fluency performance in individuals with Alzheimer’s disease compared with healthy older adults by analyzing total correct responses, number of clusters, average cluster size, and number of switches.


This is a case-control study of 39 healthy older adults and 29 older adults with a diagnosis of Alzheimer’s disease. Verb fluency performance was analyzed in terms of total number of correct verbs retrieved, number of clusters, average cluster size, and number of switches. To obtain the study outcomes, we previously conducted a procedure for categorization of the verbs that would compose the clusters. The classification of verbs was adapted for this study, including assessment by raters and analysis of inter-rater reliability.


Individuals with Alzheimer’s disease showed significantly poorer performance than healthy controls in the number of switches and total number of correct verbs retrieved. The two groups did not differ significantly in the other measures.


In this study, individuals with Alzheimer’s disease showed impaired verb fluency, characterized by a reduced number of verbs retrieved and fewer transitions between verb categories. The findings suggest that, in Alzheimer’s disease, verb fluency is more sensitive to cognitive deficits resulting from executive dysfunction than from semantic disruption.


Alzheimer’s Disease; Cognition; Language; Neuropsychology; Dementia



Investigar o desempenho na tarefa de fluência de verbos de pessoas com doença de Alzheimer em comparação à idosos saudáveis, a partir da análise do número total de palavras corretas evocadas, do número de clusters, do tamanho médio dos clusters e do número de switches.


Este é um estudo de caso-controle no qual participaram 39 idosos saudáveis e 29 participantes com diagnóstico de doença de Alzheimer. O desempenho da fluência de verbos dos participantes foi analisado quanto ao total de verbos gerados corretamente, número de clusters, tamanho médio dos clusters e número de switches. Para a obtenção dos desfechos do estudo foi realizado um processo prévio de definição das categorias de verbos que constituiriam clusters. A classificação dos verbos foi adaptada para a este estudo, incluindo a análise de juízes com investigação do índice de concordância.


Dentre as variáveis de interesse comparadas entre os grupos estudados, houve um desempenho estatisticamente inferior no grupo de pessoas com doença de Alzheimer quanto ao número de switches e total de verbos gerados corretamente. Nas demais medidas, os grupos foram semelhantes.


Neste estudo pessoas com doença de Alzheimer apresentaram déficit no desempenho da tarefa de fluência verbal de verbos, caracterizado por uma redução do número total de verbos gerados e uma menor variabilidade de categorias de verbos. Os achados sugerem que, na doença de Alzheimer, a fluência de verbos é mais sensível aos déficits cognitivos decorrentes de disfunção executiva do que aos déficits semânticos.


Doença de Alzheimer; Cognição; Linguagem; Neuropsicologia; Demência


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