The study, headed by Dr. Mark P. Gorman of Brigham and Women's Hospital and Massachusetts General Hospital in Boston, found those who had MS as children experienced 1.13 relapses annually compared with 0.4 relapses for those who didn't develop the disease until adulthood.

Symptoms of MS, an inflammatory disease in which the protective coating covering nerve cells degenerates, usually first appears in people between ages 20 and 40. Fewer than 11 percent of MS patients report symptoms appearing before age 18, according to background information in the article, leading some to theorize that MS progresses slower in those who have it in childhood.

"The higher relapse rate in the pediatric-onset group in our study may therefore suggest that patients with pediatric-onset MS are coming to medical attention closer to the true biological onset of their disorder than patients with adult onset during a more inflammatory phase, as has been previously suggested," Gorman and colleagues wrote.

The findings were published in the January issue of Archives of Neurology.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more about multiple sclerosis.