Multiple sclerosis occurs when myelin, the protective coating around nerves, is attacked by an individual’s immune system—hence, it is considered an autoimmune disease—causing inflammation and in turn problems in nerve transmission. When myelin is damaged, the transmission and nerve impulses to and from the brain is disrupted, inflaming nerve tissue, which is what causes the MS symptoms to appear.
While research indicates that MS has a genetic component, no single gene has been identified. Rather, scientists believe a number of genes may play a role. In any event, roughly 25 percent of MS patients have a relative with the disease, and twin studies show that MS occurs in both twins in about 25 to 35 percent of cases, which suggests that as many as 75 percent of MS may be attributable to non-genetic factors.
MS tends to affect individuals in North America, Europe and Australia—areas farther from the equator. In the U.S., cases are more common in northern states than in southern states, suggesting that daily sunlight exposure, which helps the body manufacture vitamin D, may also be a factor in MS.
Bacterial and viral infections, including the Epstein-Barr virus, Mycoplasma pneumoniae and Chlamydia pneumoniae, may contribute to MS as well, both in the initiation of the disease and in nerve damage, and exposure to chemical toxins, heavy metals or mercury may also be a trigger for MS. Food allergies and sensitivities may be another environmental trigger for MS, as MS is most prevalent in areas where the consumption of wheat gluten and cow’s milk, both common allergies, is high.