Cognitive processing speed in multiple sclerosis clinical practice: association with patient‐reported outcomes, employment and magnetic resonance imaging metrics

Background and purpose To analyze the relationship between cognitive processing speed, patient‐reported outcome measures (PROMs), employment and magnetic resonance imaging (MRI) metrics in a large multiple sclerosis cohort. Methods Cross‐sectional clinical data, PROMs, employment and MRI studies within 90 days of completion of the Processing Speed Test (PST), a technology‐enabled adaptation of the Symbol Digit Modalities Test, were collected. MRI was analyzed using semi‐automated methods. Correlations of PST score with PROMs and MRI metrics were examined using Spearman’s rho. Wilcoxon rank sum testing compared MRI metrics across PST score quartiles and linear regression models identified predictors of PST performance. Effects of employment and depression were also investigated. Results In 721 patients (mean age 47.6 ± 11.4 years), PST scores were significantly correlated with all MRI metrics, including cord atrophy and deep gray matter volumes. Linear regression demonstrated self‐reported physical disability, cognitive function, fatigue and social domains (adjusted R2 = 0.44, P