Patient description: The patient is a 20 year old Caucasian female presents to the clinic with one-sided vision lost and facial weakness, dysarthria and numbness lasting for 1 day. She visited her PCP and underwent brain MRI which revealed a single plaque in the brainstem. After few months, she experienced lower extremities weakness led to balance problem. The second MRI revealed another lesion in the left cerebral hemisphere. The diagnosis of Relapsing Remitting Multiple Sclerosis (RRMS) is confirmed after the second MRI. Her past surgical history is significant for a C-section 2 years ago and she has a one child. She is divorced and is not currently in any sexual relationship. She smokes 10 cigarettes per day and drinks alcohol occasionally. She is working as an editor in a publisher company and she is happy that she can keep working from home most of the time. She is under the treatment of RRMS from 7 months ago.

Clinical trial eligibility criteria: eligible ages (years): 25.0-65.0,  Secondary Progressive Multiple Sclerosis (SPMS) Patients with a confirmed diagnosis of multiple sclerosis (MS) that have entered the secondary progressive stage. Steady progression rather than relapse must be the major cause of increasing disability in the preceding 2 years. Progression can be evident from either an increase of at least 1 point if EDSS score <6, or an increase of 0.5 point if EDSS score ≥6, or clinical documentation of increasing disability 2. EDSS 4.0 5 (inclusive) 3. Aged 25 to 65 years old 4. Patients must be able and willing to comply with the terms of this protocol. 5. Written informed consent provided  Relapse within 3 months of baseline visit; 2. Patients that have been treated with steroids (intravenous and/or oral) due to MS relapse/progression within 3 months of baseline visit. These patients may undergo a further screening visit once the 3 month window has expired and may be included if no steroid treatment has been administered in the intervening period; (Note: Patients on steroids for another medical condition may be included in the trial provided the steroid prescription is not for MS relapse/progression) 3. Significant organ co-morbidity e.g. cardiac failure, renal failure, malignancy; 4. Screening levels of alanine aminotransferase (ALT) / aspartate aminotransferase (AST) or creatinine kinase (CK) ≥3 x upper limit of normal (ULN); 5. Current use of a statin; or any use within the last 6 months; 6. Medications that interact unfavourably with simvastatin as outlined in the current summary of product characteristics (SmPC); including but not limited to CYP3A4 inhibitors (e.g. itraconazole, ketoconazole, posaconazole, voriconazole, fluconazole, HIV protease inhibitors (e.g. nelfinavir), boceprevir, erythromycin, clarithromycin, telithromycin, telaprevir, nefazodone, fibrates (including fenofibrates), nicotinic acid (or products containing niacin), azole anti-fungal preparations, macrolide antibiotics, protease inhibitors, verapamil, amiodarone, amlodipine, gemfibrozil, ciclosporin, danazol, diltiazem, rifampicin, fusidic acid, grapefruit juice or alcohol abuse; 7. Primary progressive MS; 8. Diabetes mellitus type 1; 9. Uncontrolled hypothyroidism; 10. Female participants that are pregnant or breast feeding. Women of child bearing potential (WOCBP) who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period, and up to 4 weeks after the last dose of study drug; 11. Use of immunosuppressants (e.g. azathioprine, methotrexate, ciclosporine) or disease modifying treatments (avonex, rebif, betaferon, glatiramer) within the previous 6 months; 12. Use of mitoxantrone, natalizumab, alemtuzumab, daclizumab or other monoclonal antibody treatment, if treated within the last 12 months; 13. Use of fingolimod, fumarate, teriflunomide within the last 12 months; 14. Use of other experimental disease modifying treatment within the last 6 months; 15. Commencement of fampridine ≤6 months from day of randomisation; 16. Concurrent participation in another clinical trial of an investigational medicinal product or medical device; 17. Patients with rare hereditary problems of galactose intolerance, the lapp lactase deficiency or glucose-galactose malabsorption