Assessing the Cognitive Benefits of Ozanimod and Their Brain-Biomarkers in MS

To assess MS patients' cognitive improvement while on ozanimod, the investigators will compare MS patients' baseline performance to the patients' performance following treatment on memory, processing speed, verbal ability and executive function. The investigators predict that cognitive performance will improve during the ozanimod treatment compared to the baseline. Baseline-treatment differences will be assessed using repeated-measures analysis of covariance (ANCOVA) while also controlling for effects of age, education, disease duration, and expanded disability status score (EDSS). The investigators predict that improved cognitive performance will be accompanied by improvements in brain structure (e.g., increased whole brain volume) and function metrics. Thus, each MS patients' brain volume, white matter connectivity, lesion load, and resting BOLD at baseline, during treatment, and after ozanimod treatment will be measured. For each structure and function MR metric, baseline-treatment differences will be assessed using repeated-measures ANCOVA while also controlling for effects of age, education, disease duration, EDSS and brain parenchymal fraction (the ratio of functional brain tissue to whole brain volume).