This is something that Doctors, scientists, researchers and other medical professionals are simply not sure off. There are a few theories or ideas, but, if you like the "official" answer is, we don't know.
There have been and still are many theories to what causes MS or contributes to the condition. These range from the tried and tested to the weird and wonderful.
Rather than trying to skate around the subject and be vague, it's best I think to name these and if you wish to carry out your own research afterwards, then that will further educate you on the subject:
CCSVI - This is probably the most infamous of all. It reached its height of notoriety in and around 2010/2011. It prompted many people to fly to destinations around the world to have the procedure carried out, including people from the UK.
Those having the procedure in general showed positive signs and an improvement in symptoms. From my knowledge most reported an improvement in well being and not feeling as tired. Once again this specific to each person. However, it didn't live up to expectations, as initially it was thought as being the cure.
Since then research has been carried out and the theory has been discussed by many Dr's and experts across the world. Even Dr Paulo Zamboni has found need to clarify his position and readdress the theory.
So in conclusion... Is the CCSVI procedure the answer to curing MS? No. But, does see CCSVI exist in people who have MS? Yes. Scans will show that these blockages may well exist in the neck area of people with MS, but unblocking these does not cure MS. However the debate is still alive and I'm sure the research will speak for itself.
Vitamin D - This is one of the more recent trends and findings and more importantly it is one that everyone seems to agree on! It is also something we can all find out for ourselves quite easily.
Tests show that people with MS, seem to have a Vitamin D deficiency. Therefore they are prescribed or advised to toe Vitamin D supplements. The importance shown to this is not only among MSers, but among toddlers too. As mothers in the UK are told to give their toddlers Vitamin D drops and to continue this for foreseeable future! The reason given is, based on the lack of sun (source of Vitamin D) that people in the UK get.
This theory backs up the idea, that the further away from the equator you are, the more chance of getting MS. Then again it doesn't explain why people in sunny locations still get MS and why people in Dubai are regarded as medium-high risk for MS.
The only way to find out about you're own Vitamin D, is to check. There is no claim that it will cure MS, but evidence does show MSers usually have a deficiency. The question is would the general public also show a deficiency if tested their Vitamin D?
Muscular Tension - This is probably the most least known and latest theory. It is one suggested by Chongsu, a Korean Physiotherapist. He started noticing patterns amongst his MS patients, who seemed to find an ease in symptoms. He then took his findings and organised his rematch which took place in 2013.
In short his theory expands upon that one of Dr Paulo Zamboni's. where Dr Zamboni focus' on the jugular vein in the neck, Chongsu mentions a number of points around the body including the jugular vein, where blockages or stress is occurring. This according to his theory results in messages and blood flow being stopped or being interfered with.
Genes - if we look back to just after the turn of the century and into the early 2000's the idea that MS could run in the family or passed on was not really taken that seriously, however now, I'm seeing more and more evidence and information to suggest that it could be a factor.
Through speaking to people and interaction through social media, I have come across an increasing amount of siblings who both have MS. I find this worrying and interesting, as it further intensifies the question, why? Statistics now show if you have MS, the chances of your child is having MS is 67-1, this increases to 25-1 on the second child.