Predictors of Verbal Fluency Decline in People with Cognitive Dysfunctions

Background: Verbal fluency impairment is a prospective risk for dementia and conversion from Mild Cognitive Impairment (MCI) to dementia. In elderly may be related to the deficits in other cognitive domains and also with age and duration of cognitive decline. The AIM: The purpose of this study was to analyze the results of Verbal Fluency Tests (VFT) in people with cognitive decline in relation to age, duration of the cognitive decline and the level of cognitive dysfunction. Methods: 279 (177 females and 102 males) people with cognitive decline (MCI and dementia), aged 50-91 years were included in the study. For the evaluation of general cognitive abilities Mini Mental State Examination (MMSE) and for assessment of verbal fluency– Verbal Fluency Test (phonological and categorical) was applied. Statistical analysis was performed using nonparametric tests. Factor analysis of the main components of Verbal Fluency Test and MMSE were used and one-way ANOVA test in the prediction analysis was applied. Results: All dimensions of verbal fluency subscales and MMSE are explained by one factor, which indicate their similar etiological mechanism. The longer duration of the cognitive impairment the worse results in VFT and MMSE. Worse results of MMSE were associated with worse performance on VFT, the most important critical moment of deterioration was associated with scores in the range of 25-23 and 17-18 MMSE points, however there are some differences between verbal fluency categories. The most significant periods of duration of the disease for VFT performance were months 6 and 9, and for the category of categorical fluency months 6,9, as well as 26, 31-32 and 36. No significant associations between the age and VFT and MMSE results were observed. Conclusions: Verbal fluency decline is related to global cognitive functioning. Longer duration time of the disease was associated with the level of verbal fluency and cognitive decline, while the age of patients is not an important factor. The verbal fluency deterioration occurs in leaps and bounds, the critical moments for verbal fluency decline may be established based on the duration of the illness and global functioning measured by MMSE.