A multilevel linguistic analysis reveals linguistic impairments in persons with multiple sclerosis

Background: Multiple sclerosis results in sensorimotor and cognitive deficits. Previous studies have provided limited evidence of linguistic deficits, largely due to a lack of comprehensive assessments. This study addressed this gap by applying a Multilevel procedure of Linguistic Analysis (MLA) of discourse production in persons with MS (PwMS). Methods: 20 PwMS and 20 healthy controls, matched for age, education and sex, were administered tasks assessing cognitive skills and narrative discourse production abilities. The speech samples were analyzed using the MLA to assess both micro- and macrolinguistic skills. Results: The MLA highlighted significant linguistic deficits in PwMS, including frequent phonological errors, reduced grammatical accuracy, limited lexical informativeness, and impaired discourse cohesion and coherence. Microlinguistic difficulties were found to correlate with macrolinguistic impairments, confirming their interconnected nature. Fatigue level significantly affected performance in PwMS. Interestingly, no significant correlations emerged between linguistic and cognitive measures. Conclusions: The comprehensive assessment of the narrative abilities of PwMS showed their impairments span lexical, grammatical, and discourse-level processes. These findings are discussed considering recent neuroimaging evidence about the neural underpinnings of discourse production and underscore the importance of incorporating training programs that target both micro- and macrolinguistic components of narrative production into clinical care's paths.