Word finding, prosody and social cognition in multiple sclerosis.

ABSTRACT

BACKGROUND: Impairments in speech and social cognition have been reported in people with multiple sclerosis (pwMS), although their relationships with neuropsychological outcomes and their clinical utility in MS are unclear. OBJECTIVES: To evaluate word finding, prosody and social cognition in pwMS relative to healthy controls (HC). METHODS: We recruited people with relapsing MS (RMS, n = 21), progressive MS (PMS, n = 24) and HC (n = 25) from an outpatient MS clinic. Participants completed a battery of word-finding, social cognitive, neuropsychological and clinical assessments and performed a speech task for prosodic analysis. RESULTS: Of 45 pwMS, mean (SD) age was 49.4 (9.4) years, and median (range) Expanded Disability Severity Scale score was 3.5 (1.0-6.5). Compared with HC, pwMS were older and had slower information processing speed (measured with the Symbol Digit Modalities Test, SDMT) and higher depression scores. Most speech and social cognitive measures were associated with information processing speed but not with depression. Unlike speech, social cognition consistently correlated with intelligence and memory. Visual naming test mean response time (VNT-MRT) demonstrated worse outcomes in MS versus HC (p = .034, Nagelkerke's R2  = 65.0%), and in PMS versus RMS (p = .009, Nagelkerke's R2  = 50.2%). Rapid automatised object naming demonstrated worse outcomes in MS versus HC (p = .014, Nagelkerke's R2  = 49.1%). These word-finding measures showed larger effect sizes than that of the SDMT (MS vs. HC, p = .010, Nagelkerke's R2  = 40.6%; PMS vs. RMS, p = .023, Nagelkerke's R2  = 43.5%). Prosody and social cognition did not differ between MS and HC. CONCLUSIONS: Word finding, prosody and social cognition in MS are associated with information processing speed and largely independent of mood. Impairment in visual object meaning perception is potentially a unique MS disease-related deficit that could be further explored and cautiously considered as an adjunct disability metric for MS.