What (more) can verbal fluency tell us about multiple sclerosis?

Abstract

Clinical symptoms of multiple sclerosis (MS) are variable and may include cognitive impairment, which can be assessed with the verbal fluency test (VFT). This test is evaluated by counting words spoken during a 2-min period, which is not a functional approach. The objectives of this observational study were to: (1) determine new parameters that reflect communication and cognitive functions in persons with multiple sclerosis (PwMS) considering the evaluation of real-time word production in the VFT; (2) compare the results with those of a control group; and (3) evaluate the impact of including errors. A phonological fluency test ("letter P") and a semantic fluency test ("animals") were used. The real-time word production was recorded. The main variables studied were the total number of words, first word delay, moment of inflection of the curve corresponding to the change in the cognitive process, speed of word production before inflection, and maximum delay between 2 consecutive words. These variables were studied by taking into account or not errors. We included 68 PwMS and 33 healthy controls. VFT results were impaired in PwMS. The total number of words, first word delay, speed before inflection, and maximum delay were relevant to the study of phonologic fluency. For studying semantic fluency, the total number of words, first word delay, speed before inflection, and inflection time of the curve seemed relevant. Taking into account errors was significant only for total number of words. Taking into account errors in evaluating real-time word production in PwMS is of interest only for the total number of words performed but has no impact on the variables studied. These variables should be used to quantitatively evaluate verbal fluency with the objective of evaluating functionally relevant parameters (communication).