 1. To assess the efficacy of Memantine in improving the performance in the individual neuropsychological tests for attention PASAT3, SDMT, Stroop, executive Raven, MATTIS and memory 1036, SRT, in the neuropsychological global scale BRB-N Z Sepulcre et al, submitted in quality of life SF36, disability EDSS, MSFC, MSSS and fatigue Krupp. 