Impact of Natalizumab on Cognitive Performances and Fatigue in Relapsing Multiple Sclerosis: A Prospective, Open-Label, Two Years Observational Study

Background and Objectives Natalizumab reduces the relapse rate and magnetic resonance imaging activity in patients with Relapsing-Remitting Multiple Sclerosis (RRMS). So far the influence of natalizumab on cognitive functions and fatigue in MS remains uncertain. The aim of this prospective, open-label, observational study was to evaluate the possible effects of natalizumab on cognition and fatigue measures in RRMS patients treated for up to two years. Methods Cognitive performances were examined by the Rao's Brief Repeatable Battery (BRB), the Stroop test (ST) and the Cognitive Impairment Index (CII), every 12 months. Patients who failed in at least 3 tests of the BRB and the ST were classified as cognitively impaired (CI). Fatigue Severity Scale (FSS) was administered every 12 months to assess patient's self-reported fatigue. One hundred and 53 patients completed 1 and 2 year-natalizumab treatment, respectively. Results After 1 year of treatment the percentage of CI patients decreased from 29% (29/100) at baseline to 19% (19/100) ( p  = 0.031) and the mean baseline values of CII (13.52±6.85) and FSS (4.01±1.63) scores were significantly reduced (10.48±7.12, p <0.0001 and 3.61±1.56, p  = 0.008). These significant effects were confirmed in the subgroup of patients treated up to two years. Conclusions These results demonstrate that a short-term NTZ treatment may significantly improve cognitive performances and fatigue in RRMS patients.