Results from a clinical trial of more than 250 participants with progressive multiple sclerosis (MS) revealed that ibudilast was better than a placebo in slowing down brain shrinkage. The study also showed that the main side effects of ibudilast were gastrointestinal and headaches. The study was supported by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health, and published in the New England Journal of Medicine.