[Verbal fluency tasks in a Spanish sample of young adults (20-49 years of age): normative data of clustering and switching strategies].

INTRODUCTION: The aim of this study is to establish normative data on phonological and semantic verbal fluency tests, measuring total production of words, clusters and switching of words in a healthy young adult Spanish population.
MATERIAL AND METHODS: We assessed 53 healthy adults between 20-49 years old (32.8 +/- 9.5) with 8-18 years of formal education (9 +/- 3.3 years). The semantic fluency category included: animals, fruits, clothes and the initial letters F, A, S in 1 minute of time. Clustering and switching strategies were examined and scored according to a protocol elaborated ad hoc by the authors. Pearson correlations between number of "clusters", "switching" and total number of words was used and we evaluated the possible influence of age, years of schooling and gender in each one of the categories in 1 minute and in intervals of 15 seconds.
RESULTS: The variable years of formal education was the only demographical factor that significantly influenced semantic verbal fluency (r = 0.43; p = 0.04). Switching and clustering were positively correlated with the number of words generated. Clustering was highly correlated with total number of words generated on semantic fluency (r = 0.846; p < 0.01). In contrast, switching was more highly correlated than clustering with total number of words generated on phonemic fluency (r = 0.864; p < 0.01).
CONCLUSIONS: Rules for scoring switching and clustering in our population are provided. Optimal fluency performance requires some type of balance between clustering and switching strategies and should be taken into account in studies regarding verbal fluency.