Prospective Longitudinal 1-year Study of the Correlation Between Cognitive Functioning in Patients With Clinically Isolated Syndrome Suggestive of Multiple Sclerosis and Disconnection in the Brain Assessed by MRI

Inclusion Criteria: * Patients: * Men and Women * ≥16 years * Fluent French speaker * Clinically isolated neurological syndrome (CIS) compatible with a demyelinating inflammatory episode within the central nervous system, potentially beginning multiple sclerosis (MS) whatever the mode of presentation * Between 60 and 180 days from the onset * At least two clinically silent lesions on their T2-weighted brain or spinal MRI scan with a size of at least 3 mm, at least one of which being cerebral, ovoid, or periventricular * Having a medical insurance * Free and informed consent signed * Controls: * Men and Women * ≥18 years * Fluent French speaker * Having a medical insurance * Free and informed consent signed Exclusion Criteria: * Patients: * Prior documented neurological episode suggestive of MS. * Other ongoing neurological diseases. * Known chronic systemic diseases as judged by the investigator (for instance: lupus, Gougerot-Sjögren, sarcoidosis, sclerodermia, Crohn disease,…). * Other causes (trauma, tumor, radiotherapy, infections, vascular diseases, neuromyelitis optica). * Current dependence on alcohol or drugs. * Dosage change, stop or start of hypnotic or anxiolytic or antidepressive treatment less than 15 days * MRI contra-indications. * Steroid treatment less than one month (be taken orally or by infusion) at the dosage of 500mg daily. * Controls: * Known chronic psychiatric or neurologic diseases which could interfere with neuropsychological testing, not taking into account stable and mild depressive syndrome * Known chronic systemic diseases as judged by the investigator (for instance: lupus, Gougerot-Sjögren, sarcoidosis, scleroderma, Crohn disease…). * MS familial history * Current dependence on alcohol or drugs * Known cognitive impairment * Prior neuropsychological testing with the same tests less than one year * Dosage change, stop or start of hypnotic or anxiolytic or antidepressive treatment less than 2 months * Steroid treatment less than one month (be taken orally or by infusion) at the dosage of 500mg daily. * MRI contra-indications * Steroid treatment less than one month (be taken orally or by infusion) at the dosage of 500mg daily.