Original article
Verbal fluency in depressive patients with bipolar disorder

Introduction: Verbal fluency tasks are frequently applied in diagnosis of memory disorder and executive functions in people from different clinical groups. Various ways to analyze the task performance are suggested. The results are correlated with individual and clinical variables, and task procedure (task features). Numerous studies showed differences in level of verbal fluency performance in people with damages of anterior and posterior areas of brain, and pathology of right or left hemisphere. Less research concerns verbal fluency in people with bipolar disorder (BD).

Material and methods: Twenty depressive patients suffering from BD and twenty healthy controls have been examined. We have applied two kinds of phonemic fluency tasks (letters K and F) and two kinds of semantic fluency tasks (categories “animals” and “tools”). We have analyzed the number of correctly generated words, clusters and switches, also dependence between the kind and the results of tasks (phonemic fluency - high frequency letters and low frequency letters; semantic fluency - the number of classes: big/small). We have estimated the influence of individual variables on the level of verbal fluency.

Results: In depressed phase patients with BD achieve significantly lower results than controls, and the differences concern the number of generated words, clusters, and switches from high frequency categories. The level of semantic fluency was higher than the level of phonemic fluency in both groups. Individual variables (education, job) modified the level of performance in people with BD only.

Conclusions: Depressive individuals with BD present difficulties resulted more from deficit of executive functions and less from generation of semantic content, which can be related to dysfunction of prefrontal areas and their connections with posterior areas of brain.