Effects of Bipolar Disorder on the Verbal Fluency Skills of Native Speakers

Bipolar disorder (BD) is a chronic psychiatric condition characterized by episodes of mania, hypomania, and depression. Due to the cognitive impairments associated with BD, patients frequently experience difficulties in attention, memory, and executive functions, which in turn adversely affect specific aspects of their language abilities, such as word retrieval, verbal fluency, and the organization of coherent speech. The present study aims to determine the extent to which the verbal fluency skills of native Turkish-speaking individuals with BD are impaired compared to healthy controls and to identify whether there are differences in verbal fluency skills and their subcategories between bipolar I disorder (BD I) and bipolar II disorder (BD II) groups.

A cross-sectional comparative design was employed in this study, including 39 euthymic patients diagnosed with BD I or BD II and 39 healthy controls. Verbal fluency was assessed using a standardized task comprising semantic fluency, semantic switching, phonemic fluency, and automatic speech subtests. All assessments were conducted under blinded conditions, and scoring was performed by independent raters. Group comparisons were carried out using ANOVA, Kruskal-Wallis, and ANCOVA analyses; age was controlled for through covariance analysis. Additionally, sensitivity analyses were conducted within the 25-55 age range.

The control group demonstrated significantly higher performance than the BD groups across all semantic and phonemic verbal fluency tasks. No statistically significant differences were observed between the groups in automatic speech tasks. When comparing the BD I and BD II groups, a statistically significant difference was found only in the action (verb) category, with the BD II group outperforming the BD I group.

The findings indicate that bipolar disorder is associated with marked impairments in semantic and phonemic verbal fluency, while automatic speech abilities appear to be relatively preserved. Moreover, the observed difference between BD subtypes-particularly in the action (verb) category-suggests that the type of the disorder may differentially influence cognitive-linguistic functioning.