Study of Exercise on Impact of Cognitive Functioning in Multiple Sclerosis Patients

Cognitive impairment affects roughly 50% of people with multiple sclerosis (MS). There are currently no satisfactory medical treatments for cognitive impairments related to MS and alternative forms of treatment are needed. Exercise training can improve cognition in older adults and people with mild cognitive impairments, including those with early Alzheimer's disease. Therefore, the investigators plan to conduct the first definitive study that will test the theory that moderately intense aerobic exercise can improve cognition in people with MS-related impairment - specifically in information processing speed - more so than non-aerobic stretching and toning (both forms of exercise will be performed 3 days per week for 6 months). Primary study hypothesis: The investigators hypothesize greater improvement in speed of information processing from pre- to post-treatment in the aerobic exercise group compared to the stretching and toning group (attention control). Secondary study hypothesis: The investigators hypothesize greater improvement in other cognitive domains and patient reported outcomes from pre- to post-testing in the aerobic exercise group compared to the stretching and toning group (attention control). The investigators plan to recruit 125 adults with MS who can walk without assistance and without rest for at least 100 meters and have mild weaknesses in information processing speed. The investigators will randomly assign 50% of participants to an aerobic exercise program and 50% to a non-aerobic exercise program (stretching and toning). In order to determine whether the intervention is successful, the investigators will compare cognitive functioning in both exercise groups before the exercise-training program, at the end of the 6-month training program and three months after the end of the training program. If our study findings support our hypotheses, this would be a relatively no-barriers treatment option to further explore for other people with MS includ