Multiple sclerosis is a disease that affects the spinal cord and brain. This chronic condition may lead to many symptoms, such as balance issues, sensation problems, and other challenges with your leg movements, arm, and vision. Most cases tend to be mild with proper treatment. However, multiple sclerosis may also lead to severe disability and reduced life expectancy. The condition is typically diagnosed in those from 20 to 40 years old. It is more common in females than in males. Overall, multiple sclerosis is the most common causes of disability in young adults.