BackgroundNeuropsychological batteries are infrequently used to assess cognitive impairment in multiple sclerosis because they are time-consuming and require trained personnel. The Symbol Digit Modalities Test (SDMT) is suggested to be a useful screening tool to measure cognitive impairment in multiple sclerosis patients and is more valid and reliable over time than the Paced Auditory Serial Addition Test (PASAT). The purpose of this study was to evaluate which of these tests was more sensitive to cognitive impairment at one-year follow-up.MethodsA total of 237 patients with relapsing-remitting multiple sclerosis and 57 healthy controls underwent a complete neuropsychological assessment. One year later, we assessed 196 patients using the Brief Repeatable Battery of Neuropsychological Tests. We also administered other executive function and prospective memory tests, together with fatigue and depression questionnaires.ResultsA total of 33.8% of patients were classified as cognitively impaired. The SDMT and the PASAT 3 seconds test (PASAT3) had a sensitivity of 0.809 and 0.783, respectively, thereby classifying patients as cognitively impaired. Analysis of 196 patients one year later showed 31.6% had cognitive impairment compared with 27.6% at the first assessment. The sensitivity to detect cognitive impairment after one year was 0.824 for SDMT and 0.796 for PASAT3. When the predictors were removed from the comparative standard battery, SDMT still showed a slightly higher sensitivity. Both SDMT and PASAT3 correlated significantly with all tests, but SDMT showed higher correlation values. Furthermore, SDMT was completed by all subjects while PASAT3 was completed by 86.9% of patients and 94.7% of controls.ConclusionsSDMT is simpler to administer than PASAT3 and may be slightly more sensitive to MS cognitive impairment. It could thus be a suitable test to assess cognitive impairment routinely in people with relapsing-remitting multiple sclerosis.

Multiple sclerosis (MS) is a chronic central nervous system disorder characterized by white matter inflammation, demyelination and neurodegeneration. Although cognitive dysfunction is a common manifestation, it may go unnoticed in recently-diagnosed patients. Prior studies suggest MS patients develop compensatory mechanisms potentially involving enhanced performance monitoring. Here we assessed the performance monitoring system in early-stage MS patients using the error-related negativity (ERN), an event-related brain potential (ERP) observed following behavioral errors. Twenty-seven early-stage MS patients and 31 controls were neuropsychologically assessed. Electroencephalography recordings were obtained while participants performed: a) a stop task and b) an auditory oddball task. Behavior and ERP measures were assessed. No differences in performance were found between groups in most neuropsychological tests or in behavior or ERP components in the auditory oddball task. However, the amplitude of the ERN associated with stop errors in the stop task was significantly higher in patients. ERN amplitude correlated positively with scores on the Expanded Disability Status Scale and the Multiple Sclerosis Severity Score, and negatively with the time since last relapse. Patients showed higher neuronal recruitment in tasks involving performance monitoring. Results suggest the development of compensatory brain mechanisms in early-stage MS and reflect the sensitivity of the ERN to detect these changes.

IntroductionAntibodies targeting the inward-rectifying potassium channel KIR4.1 have been associated with multiple sclerosis (MS) but studies using diverse techniques have failed to replicate this association. The detection of these antibodies is challenging; KIR4.1 glycosylation patterns and the use of diverse technical approaches may account for the disparity of results. We aimed to replicate the association using three different approaches to overcome the technical limitations of a single technique. We also performed a systematic review to examine the association of anti-KIR4.1 antibodies with MS.MethodsSerum samples from patients with MS (n = 108) and controls (n = 77) were tested for the presence of anti-KIR4.1 antibodies using three methods: 1) by ELISA with the low-glycosylated fraction of recombinant KIR4.1 purified from transfected HEK293 cells according to original protocols; 2) by immunocytochemistry using KIR4.1-transfected HEK293 cells; and 3) by immunocytochemistry using the KIR4.1.-transfected MO3.13 oligodendrocyte cell line. We developed a systematic review and meta-analysis of the association of anti-KIR4.1 antibodies with MS according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.ResultsWe did not detect anti-KIR4.1 antibodies in the MS patients or in controls using ELISA. Neither did we detect any significant reactivity against the antigen on the cell surface using the KIR4.1-transfected HEK293 cells or the KIR4.1-transfected MO3.13 cells. We included 13 prospective controlled studies in the systematic review. Only three studies showed a positive association between anti-KIR4.1 and MS. Clinical and statistical heterogeneity between studies precluded meta-analysis of their results.ConclusionWe found no association between anti-KIR4.1 antibody positivity and MS. Although this lack of replication may be due to technical limitations, evidence from our study and others is mounting against the role of KIR4.1 as a relevant MS autoantigen.