Assessment of phonemic verbal fluency in Portuguese patients with multiple sclerosis.

Background: Executive dysfunction occurs in 15% to 20% of multiple sclerosis (MS) patients and verbal fluency tests are frequently used to assess this deficit. The Word List Generation (WLG) is one of the most used measures in MS. This study aims to compare the performance of WLG of MS patients and healthy controls and to analyze the influence of clinical and demographic factors on the performance of MS patients.

Methods: One hundred and nine MS patients and an age- and gender-matched group of 138 healthy controls were evaluated with WLG Portuguese version, as well as other tests from the Brief Repeatable Battery of Neuropsychological Tests (BRBN-T), subtests from WAIS, a phonemic fluency test (M, R, and P), and measures of psychological symptomatology and cognitive fatigue. The MS group (70.6% females) was mainly diagnosed with RRMS (89.2%).

Results: The MS group performed significantly lower than healthy controls on the WLG. In the MS group, this performance was significantly correlated with the level of education. Significant differences were found between the two groups regarding cognitive fatigue, with MS patients reporting higher levels than healthy controls. However, this variable was not related to the performance on the WLG for MS patients.

Conclusions: This study suggests that MS is associated with large levels of cognitive decline on the phonemic verbal fluency tests. These results are consistent with other studies and highlight the importance of verbal fluency and cognitive speed measures in the neuropsychological assessment of MS. Deficits on this task seem to be highly related to the level of education of the patient rather than other demographic and clinical factors.