A Longitudinal Study of Brain Atrophy in MS Patients Over 5 Years

Inclusion Criteria: * Participation in natalizumab 1-year follow-up study * Participants were aged 18-65 * Have clinically definite MS according to the Polman criteria of either RR or RSP disease type * EDSS scores ≤6.5 * disease duration \<30 years * normal kidney function (creatinine clearance \>59 mL/min) * started therapy either with natalizumab or IM interferon beta-1a (IFNβ-1a) * Signed informed consent * Normal kidney functioning (creatinine clearance \>59) * None of the exclusion criteria Exclusion Criteria: * A clinically significant infectious illness (e.g., cellulitis, abscess, pneumonia, septicemia) within 30 days prior to 5-year follow-up visit * Nursing mothers or pregnant women who will need to undergo 5-year follow-up MRI * Unwillingness or inability to comply with the requirements of this protocol including the presence of any condition (physical, mental, or social) that is likely to affect the subject's ability to comply with the study protocol * Any other reasons that, in the opinion of the Investigator, indicate that the subject is unsuitable for enrollment into this study