Lipoic Acid for Secondary Progressive Multiple Sclerosis (MS)

Inclusion Criteria: * Diagnosis of SPMS * Age 40-70 years * Able to understand English and able to give informed consent Exclusion Criteria: * Unable to undergo MRI testing * For ambulatory subjects only, a self-reported medical or neurological condition other than MS that is a cause of progressive or fluctuating problems that affect walking(e.g. worsening neuropathy, uncontrolled lower extremity arthritis, uncontrolled heart or lung disease) * For ambulatory subjects only, fixed and/or stable conditions of less than 1 years duration that affect walking (e.g. joint replacement, lumbar stenosis, alcoholism, stroke, etc.) * Pregnant or breast-feeding. * Current major disease or disorder other than MS (such as cancer, kidney, heart or lung disease, post-traumatic stress disorder) that may interfere with study procedures * Natalizumab, mitoxantrone, azathioprine taken in the last 12 months * Other immunosuppressants or chemotherapies taken in the last 12 months * Scheduled (every 3 months or more frequently) IV steroids used in the last 12 months * IV or oral steroids taken in the past 60 days. * Lipoic acid taken in the past 60 days. * Subject has insulin-dependent diabetes or is not controlled on oral diabetes medications