Early Cognitive Impairment in Multiple Sclerosis

Cognitive impairment is one of the symptoms of Multiple Sclerosis (MS), and it may occur during the first years of the disease. It usually affects attention, information processing speed and short term memory. To date, the mechanisms of this specific symptom remain unclear (local or global inflammation, neurodegenerative processes). Magnetic Resonance Imaging (MRI) can be useful to understand the pathophysiology of cognitive impairment in MS. The investigators will combine conventional and non conventional MRI sequences to determine the respective role of white matter and grey matter injury and the cortical reorganization of neuronal networks.