Effects of 2-year treatment with dimethyl fumarate on cognition and functional impairment in patients with relapsing remitting multiple sclerosis

Background A significant proportion of patients with multiple sclerosis (MS) show cognitive impairment. Objective To evaluate the effect of 2-year treatment with oral dimethyl fumarate (DMF) on cognition in relapsing remitting MS (RRMS). Methods In this prospective single-arm study RRMS patients treated with DMF underwent a wide battery of tests, including an extensive neuropsychological evaluation, clinical and patient-reported outcomes (PROs) and quality of life (QoL). Primary endpoints were the proportion of patients with cognitive impairment at baseline and of patients with cognitive worsening over 2 years. Results Overall, 217 patients (74.2% females, mean age 37.3 years) receiving DMF were recruited, and 156 (67.2%) completed the study. Of the 49 patients with cognitive impairment at baseline, 34 had 2-year data: 15 (44.1%) patients worsened and 19 (55.9%) did not. The cognitive impairment index improved in one third of patients at 2 years. Less than 20% of patients had relapses at 2 years (annualized relapse rate: 0.190). Few patients had disability progression. PROs (fatigue, depression, impairment in work/social activities), QoL, and most of neuropsychological tests significantly improved vs. baseline. Conclusion The 2-year treatment with DMF was associated with slowing of cognitive impairment and with significant improvements in QoL and psychosocial function.