The influence of manual dexterity on processing speed assessment in multiple sclerosis: A comparison of the PST and oral SDMT

Cognitive impairment (CI) is a common symptom in persons with Multiple Sclerosis (PwMS), specifically information processing speed (IPS) impairment. The Symbol Digit Modalities Test (SDMT), which requires in-person testing, is a well-established measure for screening for IPS and CI in clinic settings. The Processing Speed Test (PST), a self-administered iPad-based tool, has been proposed as an alternative. Preliminary studies suggest that the PST can effectively differentiate PwMS from healthy controls and correlates with MRI results. This study aims to investigate if the relationship between the PST and oral SDMT is affected by manual dexterity or level of disability. A cohort of 100 PwMS completed both the PST and SDMT, as well the 9-Hole Peg Test (9HPT) and Expanded Disability Status Scale (EDSS). The strong positive correlation found between the PST and SDMT was maintained across all subgroups based on 9HPT performance and EDSS functional system scores. Our findings indicate that the PST is comparable to the SDMT for PwMS regardless of manual dexterity. This validates PST as a time-efficient, self-administered alternative that can reduce clinical burden in MS care.