A new computerised cognitive test for the detection of information processing speed impairment in multiple sclerosis

Background: Cognitive impairment in multiple sclerosis (MS) primarily applies to information processing speed (IPS). Objective: To evaluate psychometric properties of a new digit/symbol substitution test in healthy subjects and patients with MS, and assess its ability to detect IPS impairment in patients with MS. Methods: A sample of MS patients, 60 relapsing-remitting (RRMS) and 41 primary progressive MS (PPMS), and 415 healthy controls (HCs) underwent an IPS battery, including assessment of reaction times of subtests of the Test of Attentional Performance battery and a newly developed in-house digit/symbol substitution task, the Computerised Speed Cognitive Test (CSCT). The CSCT was additionally evaluated in a second cohort of 31 RRMS and 12 progressive MS patients, for comparison with the Symbol Digit Modalities Test (SDMT). Results: The CSCT had good reliability in both HCs and patients with MS. It showed a weak practice effect at the 6-month time point. This test had good ecological validity in MS patients. There was a strong correlation between the CSCT with the SDMT and with other IPS tests in patients with MS. The CSCT had the best sensitivity for predicting IPS impairment and was one of the most accurate tests among the IPS battery. Conclusion: The CSCT appeared as a good candidate for detecting IPS impairment in MS patients.