Verbal fluency in cerebral small vessel disease and Alzheimer's disease

Patterns of verbal fluency deficits have been explored across different neurodegenerative disorders. This study sought to investigate the specific pattern of verbal fluency performance in cerebral small vessel disease (SVD), which is the most common cause of vascular cognitive impairment, and compare this with Alzheimer's disease (AD). Participants with SVD (n = 45), AD (n = 24) and healthy controls (n = 80) completed assessments of semantic and phonemic fluency. Mixed-model analyses of covariance were used to compare performance on the different fluency tasks between the groups, and a discriminant function analysis was conducted to examine group differentiation. The SVD group was impaired in both fluency tasks when compared to the controls. In contrast, the AD group displayed impairment in semantic fluency only. Discriminant function analysis revealed that fluency scores correctly classified 80% of SVD patients and 92% of AD patients. The pattern of performance observed in the SVD group may reflect deficits in executive function and processing speed impacting equivalently on semantic and phonemic fluency. The differences between the SVD and AD groups highlighted in this study may be useful for distinguishing between these conditions.