Abstract
Verbal fluency is often included as part of cognitive assessment in Parkinson's disease (PD). It has been related not only to executive processes, but also to semantic processing ability. Thus, verbal fluency represents an important domain for monitoring cognitive decline in cortical and subcortical disorders. Although differences in verbal fluency have been reported when comparing PD and controls, little attention has been devoted to understanding whether motor symptom severity might be associated with verbal fluency performance. The aim of the present study was to investigate the relationship between motor symptom severity and phonetic and category verbal fluency. Thirty-one PD patients with lower (n=15) and higher (n=16) UPDRS motor scores were assessed in phonetic (letters) and category (animal) verbal fluency. The results show that the more impaired group was able to generate fewer words in both tests, indicating that the progression of disease severity in PD has an impact on verbal fluency, especially in phonetic fluency. Looking more closely at performance revealed that the more impaired patients exhibited reduced switching in the phonemic fluency task which has been partly attributed to slower movement initiation. In the category fluency task the more impaired patients had more difficulty with clustering words which could be related to slowness in thinking (bradyphrenia) observed in PD patients in the later stages of the disease.
