Causes of Multiple Sclerosis

The cause of Multiple Sclerosis is still largely unknown. There are several different theories which have been considered to try to explain the possible cause(s) of Multiple Sclerosis; some of these theories are plausible, although none of them has yet been proven. The most common theories of the causes of MS are genetic, infectious, environmental or of immune system origin.

Immune system - this theory is probably the most common amongst immunologists and researchers. Multiple Sclerosis could be the consequence of an unexplained change in the ‘behaviour’ of the immune system’s T-cells, which attack the body and in particular the cells in the brain and the spinal cord, damaging the myelin of nerves. This damage impacts on the good functioning of the nerves, thus generating the MS symptoms and disabilities.

Genetic theory - although Multiple Sclerosis is not considered a hereditary disease or a ‘genetic’ disease as such, it has been proved that the risk of developing it increases if a person has a relative - especially siblings, parents and children - suffering from it. Some researchers believe that certain genetic combinations could increase the chances of developing the disease. According to this theory, genes could be one factor - amongst others - that determine the risk of developing Multiple Sclerosis. Some scientists believe that there is more than one gene that makes one individual more likely to get MS, while others have theorised that the condition develops because of environmental factors that trigger a genetic predisposition.

Environmental Risk Theory - several risk factors have been indicated as possible causes of MS, although for all of them there is still not enough evidence. People living in certain geographical areas or belonging to certain ethnic groups seem to have an increased risk of developing Multiple Sclerosis. MS seem to be more common in temperate zones in both hemispheres and amongst white people and its prevalence increases with distance from the equator. North America, Australia, New Zealand, Scotland, Scandinavia and other Northern European countries in general have a higher prevalence of MS. There are also some MS ‘epidemics’, like that on the Danish coast after WWII. These facts seem to suggest the environmental causes play a role in the development of MS. Some researchers believe that these environmental causes could include:

not enough vitamin D intakelack of sun exposuresevere stressgoutoccupational exposure to toxin, mainly solventsdiet smokinghormone consumptiongeomagnetism, which is are the magnetic impact of the earth and its atmosphere

Infectious theory - Some researchers theorise that MS could be a type of infection produced by a common bacteria or virus. This hypothesis is based on some epidemiology variations that scientists have noticed when analysing MS incidence, such as the higher presence of the disease amongst members of the same family or the changes in the percentage of risks which occur when a person migrates at young age.

Two main theories have been elaborated on how this infection may occur:

The prevalence theory - attributes the cause of MS to an infectious agent which is present in geographical areas with a higher prevalence of Multiple Sclerosis. This widespread microbe would cause in most individuals a chronic asymptomatic infection. The infection could cause demyelination in certain individuals but only many years after contact. There are several viruses which may be the agent that can cause Multiple Sclerosis as they have been found at high levels in the cerebrospinal fluid of MS patients. Among these are different types of the Herpes virus, Varicella zoster virus and especially the Epstein-Barr virus, which is another virus of the Herpes family.The hygiene theory - hypothesizes that Multiple Sclerosis is an autoimmune reaction triggered in particular individuals by multiple infective microbes, with risk increasing with the age at the time of the infection.