“Multiple sclerosis (MS) is one of the most widespread disabling neurological conditions of young adults around the world. It affects almost 1 million people in the United States, and about 2.9 million people worldwide.

There are relapsing-remitting and progressive types of MS, but the course is rarely predictable. Researchers still don’t fully understand the cause of MS or why the rate of progression is so difficult to determine.”

Healthline (Multiple Sclerosis: Facts, Statistics, and You)