Microstructural analysis of verbal fluency performance in relapsing-remitting multiple sclerosis based on the impact of disability level

Abstract

Verbal fluency (VF) evaluates language and cognitive abilities. This study compared VF in Relapsing-Remitting Multiple Sclerosis (RRMS) and healthy controls (HC), examining variables including correct responses (CR), mean cluster size (MCS), switches (S), and fluency difference score (FDS). RRMS participants were subgrouped by Expanded Disability Status Scale (EDSS), to explore the relationship between MS severity and VF. Twenty-four RRMS participants and matched HCs underwent Mini-Mental State Exam and VF Test. Statistical analysis compared VF between RRMS subgroups based on severity levels, and in HC. RRMS significantly impacted the CR, and S (CRSF p = 0.01, SSF p = 0.002; CRPF=0.002, SPF p = 0.002), while there was no significant difference in FDS between RRMS groups (p = 0.9). No significant relationship was found between EDSS scores, and VF subtests (CRSF p = 0.061, MCSSF p = 0.46, SSF p = 0.051, CRPF p = 0.521, MCSPF p = 0.966, SPF p = 0.599). In RRMS, our results demonstrate impairments in all VF parameters except the MCSSF+PF, and FDS. This study suggests that intact MCSSF+PF may reflect preserved verbal memory and word recall, while significant switching differences may indicate impaired cognitive flexibility. Similar FDS to those of HC suggest that no performance discrepancy in subtests in RRMS. Intact MCS might be a distinctive pattern in the early clinical stage of MS.