Developing MS is not your fault and has nothing to do with lifestyle or behaviour. Although no-one is certain why people get MS, research suggests that it is caused by a combination of genetic and environmental factors.

As far as we know, around 85,000 people in the UK have MS - that's about one in every 800-1000 people. Most people get diagnosed aged between 20 and 40. It's almost twice as common in women as men.

You didn't catch MS, you developed it. It occurs when there is damage to the protective material (myelin) around the nerves in the central nervous system (the brain and spinal cord). When myelin is damaged, messages from your brain to your body are slower or do not get through at all, causing symptoms of MS like fatigue and difficulty walking or speaking. These symptoms may come and go.

MS is an autoimmune condition, meaning that your immune system attacks your own body. Normally the immune system helps to fight off infections, but in MS it mistakes your own body's tissue as foreign.

The myelin damage leaves nerve fibres partially or completely exposed, with scars known as lesions or plaques. This lack of protection then disrupts messages travelling along the nerve fibres. Think of it as an electrical cable whose insulating plastic has been damaged. The electrical impulse can't make it down the cable so messages can slow down, become distorted, short circuit, or not get through at all.

As well as myelin loss, there can sometimes be damage to the actual nerve fibres. It is this nerve damage that causes the progression of disability that can occur over time.