An analysis of verbal fluency task performance profiles in patients with vascular brain pathology

Abstract

Aim: Considering the data on the important role of verbal fluency tasks in neuropsychological diagnosis and the models of hemispherically specialised modulation of processes essential for different types of verbal fluency, we made an attempt to identify differences in correct and incorrect performance of 5 verbal fluency tasks between patients with vascular cerebral pathology, including hypertension, and healthy individuals. We also analysed task performance profiles within the groups. Materials and methods: The study included healthy volunteers (n = 36), hypertensive individuals (n = 33), and patients after left (n = 15) or right hemisphere stroke (n = 30) – 114 subjects in total. We used the Frenchay Aphasia Screening Test (FAST) to exclude patients with significant language difficulties/aphasia. We used 5 verbal fluency tasks: semantic (Animals), phonemic (“k”), verb fluency and two emotional tasks: Joy and Fear. We used general linear models for repeated measures for the analysis of correctly and incorrectly performed tasks. Results: The profiles of correct responses for all 5 tasks were similar in all groups, with quantitative intergroup differences. The highest number of correct responses appeared in the semantic, phonemic and verb fluency tasks, whereas the lowest number in the emotional tasks. Hypertensive individuals scored statistically insignificantly lower than healthy individuals, whereas patients after right/left hemisphere stroke scored significantly lower compared to both these groups. Despite a large number of errors, healthy individuals had the highest scores. Patients after right hemisphere stroke showed little differentiation in the number of correct responses in subsequent tasks. There were no intergroup differences in the level of performance of emotional tasks with different valences (positive and negative). Healthy and hypertensive individuals were characterised by a distinct heterogeneity of correct and incorrect responses in various tasks. Patients with brain pathology, regardless of its lateralisation, performed these tasks at a similar level, with left hemisphere damage resulting in the highest number of errors, mainly in semantic and phonemic tasks, and with right hemisphere pathology associated with errors in all types of tasks. The difficulties in patients with left hemisphere damage may result from weaker phonological and lexical processes, including access to semantic features of a word, while the low scores of patients with right hemisphere damage may be a consequence of impaired attention and executive processes. Conclusions: Patients with vascular pathology of the brain hemispheres achieved significantly lower scores in all types of fluency, while hypertensive individuals scored insignificantly lower than healthy subjects. This means that the method can be useful in differentiating between healthy individuals and patients with central nervous system damage, as well as those at risk. Future research should focus on a detailed analysis of the types of errors made by patients with hemispheric damage in various types of verbal fluency tasks. An analysis of the location of the pathology in the anterior-posterior dimension of each hemisphere could reveal specific features of verbal fluency.