What Are the Risk Factors for Multiple Sclerosis

What Are the Risk Factors for Multiple Sclerosis

• Age. Multiple sclerosis often occurs at age 20–40. Almost 85% of multiple sclerosis patients have the relapsing-remitting form, in which the symptoms of the disease are mild and in a cycle of recurrence and remission. The condition may persist for 10–15 years. After that, 95% of the patients develop secondary progressive multiple sclerosis, which worsens the symptoms of the disease.

• Family and genetics. Having a parent or sibling who has suffered from multiple sclerosis increases your risk of the disease. Gene polymorphic variants are associated with multiple sclerosis, among which HLA-RB1 variants are the most well documented. HLA genes encode a group of proteins known as the human leukocyte antigen complex, which are responsible for differentiating self from nonself. Mutations of HLA-RB1 genes cause the immune cells to attack the myelin shield of the nerve fiber, mistaking it as foreign, leading to multiple sclerosis.

• Infection. The majority of multiple sclerosis patients were infected previously by the Epstein-Barr virus. Infection by the Epstein-Barr virus alone does not lead to any serious illness. However, mutations of HLA-RB1 genes together with the infection increase the risk of multiple sclerosis.

• Vitamin D. People who live at higher latitudes have an increased risk of multiple sclerosis. The higher the latitude, the lower the strength of ultraviolet B from the sun's rays, and the weaker the ability of the skin to produce vitamin D. Multiple sclerosis patients often have lower blood levels of vitamin D compared to healthy individuals. Vitamin D regulates immune functions and prevents autoimmune disorders. Vitamin D deficiency increases the risk of multiple sclerosis.

• Smoking. The role of the blood-brain barrier is to prevent harmful substances from getting into the brain. Toxic chemicals from cigarette smoke can injure the structural integrity of the blood-brain barrier, allowing leukocytes to enter the nerve cells and cause damage to the myelin shield, increasing the risk of multiple sclerosis. Smoking cigarettes can exacerbate the risk of multiple sclerosis, particularly in individuals with HLA-RB1 gene variants.