Causes of Multiple Sclerosis : Herpes, Measles, Environment, Genetics?
The precise causes of multiple sclerosis are not known although it is generally accepted that it is an autoimmune disease whereby the body attacks its own cells or tissues.
In the case of MS the target of the attack is myelin - the protective sheath surrounding the nerves in both the brain and the spinal cord. These nerves become scarred and it's this damage which interrupts the normal transmission of the central nervous system, so producing the symptoms of Multiple Sclerosis.
But why the body should turn on itself in this way remains a mystery. It would be great to give a definitive answer to this one, but at present that's not going to happen. Researchers all over the world are coming up with theories but there is, as yet, no real long term evidence to back them up. They do generally agree that environmental and genetic factors are involved, but what actually triggers the disease is still up for debate.
MS Theories and Prognosis
Herpes and Measles Virus: One theory is that exposure to viruses such as measles and herpes, both of which are known to causes inflammation of the nerves, could be to blame. Some medics believe that these viruses can lie dormant in the body, waiting for a lowering of the body's natural resistance before striking and starting the autoimmune process. Or it could be down to some sort of environmental agent.
Researchers have discovered epidemics of Multiple Sclerosis. There were four outbreaks in the Faroe Islands over a 40 year period after World War II. The islands were occupied by British troops and researchers believe the soldiers unknowingly brought a virus or bacteria with them during their occupation. But this theory has not been definitely proved, just like no other virus has been proved to cause MS.
Environmental Factors: Certainly MS is more common in the northern hemisphere. It is virtually unheard of in places like Malaysia or other areas of the "inter-tropical belt". The disease is, however, relatively common in Britain, Canada, northern Europe and North America, southern Australia and New Zealand. This may indicate that an environmental agent peculiar to those parts of the world is the trigger. But again there's no hard evidence to back this up.
Studies have also shown that when people move from a high risk area to a low risk area, their risk of developing the disease only drops if the move occurred after the age of 15. This could suggest that exposure to some sort of virus or environmental agent before that age increases a person's risk of developing MS.
Genetics: Another school of thought is that genetics are involved. MS is not directly inherited and certainly no one gene has been found to cause it. But having a parent or sibling with the disease increases a person's risk. The risk is very small - siblings of an affected person have a only a 2% risk of developing Multiple Sclerosis.
However some neurologists believe that a person is born with a genetic predisposition to react to some environmental factor, which may trigger an autoimmune response.
There is also a suggestion that hormones, such as the female sex hormones oestrogen, and progesterone can affect the body's immune system. During pregnancy these hormones are quite high, which could explain why the disease slows right down in pregnant women.
The debate continues.