Observational study based on a prospective multicentre cohort of patients with MS Objectives 1. To describe the longitudinal pattern of cognitive performance in MS, MS as measured by Brain on Track, compared with the performance of healthy controls. 2. To compare the variation in cognitive performance measured with Brain on Track with that obtained from brief screening tools and a neuropsychological battery. 3. To explore the association of cognitive decline over one year with new white matter lesions and cortical atrophy in the cerebral MRI and evaluate the hypothesis of predominantly cognitive relapses in MS by exploring the association of recent cognitive decline with new white matter lesions (WML) on MRI.
