Multiple sclerosis (MS) affects an estimated 2.3 million people worldwide.

Although its exact prevalence in the United States is not known, the condition tends to be more common the farther from the equator that one travels.

MS affects the central nervous system (CNS) and can cause a range of symptoms — often involving problems with movement, sensation, balance, and vision.

Symptoms generally appear when an individual is in their 20s or 30s. Some can be managed, and, in some cases, progression of the disease can be slowed. However, there is still no cure.