Multiple sclerosis is an autoimmune disease in which the immune system of the body attacks the myelin, a protective layer covering the nerve fibers. It can affect the brain, spinal cord, and even the optic nerve in the eye. Although there is no cure for this disease, with the help of treatments for multiple sclerosis, its various symptoms can be managed. The effects and symptoms of this disease are different among different patients.

1. Types of multiple sclerosis
The different types of multiple sclerosis are as follows:

• Clinically isolated syndrome (CIS)
  This type of multiple sclerosis involves a single episode of the syndrome that lasts for about 24 hours. It is caused as a result of demyelination, i.e. damage of myelin in the central nervous system.
• Relapsing-remitting multiple sclerosis (RRMS)
  It is the most common form of multiple sclerosis, affecting around 85 percent of all the patients. Various treatments for multiple sclerosis are administered to manage its symptoms along with slowing down the progress of the disease. It involves episodes, with new or increasing episodes, followed by remissions. During this remission period, symptoms are milder or might be absent. There is no progression of this disease.
• Primary-progressive multiple sclerosis (PPMS)
  In this type, from the onset of the symptoms, neurological functions gradually worsen. Patients might experience periods of stability. Sometimes, the symptoms worsen, and then they get better.
• Secondary-progressive multiple sclerosis (SPMS)
  In this type of multiple sclerosis, patients experience episodes of relapse and remission; however, over time, the disease advances steadily. The severity of symptoms varies among patients. Patients who experience milder symptoms do not require any of the treatments for multiple sclerosis.

2. Causes and risk factors of multiple sclerosis
The following factors can increase the risk of occurrence of this disease:

• Age
  Though this disease can occur at any age, most of the patients are diagnosed between the ages of 20 and 40.
• Family history
  A person whose parents or siblings have been affected by this disease is likely to suffer from this health condition. Doctors often consider these factors for a proper diagnosis before deciding on the treatments for multiple sclerosis.
• Infections
  Different viruses, including Epstein-Barr, have been linked to this health disorder.
• Other autoimmune diseases
  Patients suffering from type 1 diabetes, or thyroid or inflammatory bowel disease, are at a higher risk of developing this disease.
• Vitamin D and vitamin B12 deficiency
  This disease is found to be common among people who receive less sun exposure. This affects the production of vitamin D by the body. Hence, many experts believe that lower levels of vitamin D might affect the functions of the immune system. Additionally, the body requires vitamin B to produce myelin. Therefore, a deficiency of this vitamin might lead to the development of neurological diseases, including multiple sclerosis.

Though the exact causes are not known, a combination of all these genetic and environmental factors can increase the risk of development of multiple sclerosis among people.