Anyone diagnosed with multiple sclerosis (MS) can have a form of the disease known as primary-progressive multiple sclerosis (PPMS). Most commonly, PPMS is found in individuals over the age of 40. However, it can be diagnosed at any age. Today, there are up to 10,000 children in the United States with multiple sclerosis. Of the adults with the disease, it is thought that up to 5 percent of them had symptoms of the disease before they reached 18. Roughly 15 percent of those diagnosed with MS have the form of the disease known as PPMS.