Nearly three million people around the world have multiple sclerosis, or MS. In the United States alone, around one million adults live with the disease, a number that has doubled since 1975. MS is a progressive and debilitating disease that damages the nervous system, causing loss of mobility, sensory impairment, and multiple other symptoms. The book explains that the condition is caused by a range of factors, from genetics to where a person lives. Readers will learn that MS symptoms can vary in intensity, from mild in some people to very debilitating in others, and that episodes of symptoms can improve or worsen periodically through a person's life.