Which statement correctly identifies a disease-modifying therapy for multiple sclerosis?

• A. Interferon beta-1a
• B. Prednisone
• C. Azathioprine
• D. Dexamethasone

Answer: (A)

Disease-modifying therapies for MS aim to reduce relapse frequency and slow the progression of disability by altering the immune response. Interferon beta-1a fits this role because it modulates the immune system rather than just treating acute symptoms. It dampens autoreactive T-cell activity, shifts cytokine balance toward an anti-inflammatory state, and helps maintain the blood-brain barrier. Clinically, this translates to fewer relapses and fewer new MRI lesions, contributing to slower disease progression in relapsing-remitting MS.

Corticosteroids like prednisone or dexamethasone address acute relapses to accelerate recovery but do not change the long-term course of the disease. Azathioprine is an immunosuppressant with some historical use in MS, but it is not a standard first-line disease-modifying therapy due to less robust efficacy and tolerability compared with established DMTs.