If someone you know has recently been diagnosed with multiple sclerosis, or MS, you may like to learn more about the condition, so you can better understand their symptoms and experiences.

MS is the most common cause of non-traumatic neurological disability in young adults. It's not a terminal illness but it is a lifelong condition. And it's not infectious or contagious.

We spoke to some experts to find out more about how MS can impact daily life...

What exactly is MS?

"Multiple sclerosis, or MS, is a disease where the immune system attacks the nervous system," says Dr Ben Turner, consultant neurologist at London Bridge Hospital, part of HCA Healthcare UK.

'Sclerosis' means scarring or hardening of tiny patches of tissue, and 'multiple' is added because this can happen in more than one place.

"The condition affects the brain and spinal cord and so can have a wide range of symptoms, which vary from person to person," Turner adds. It affects women about twice as often as men, and typically starts in the second or third decade of life but can potentially be seen at any age.

"While it is a lifelong condition that sometimes leads to serious disability, it can occasionally be mild, in which case symptoms may be treated successfully," Turner says. "In the past decade, there's been a development of highly effective therapies which can contain the condition, which has transformed the outcome for many individuals with MS."

What are the symptoms of MS?

The symptoms of MS can range from numbness and tingling of different parts of the body to limb weakness, visual disturbances, balance issues, urinary issues, pain, and fatigue, says Turner.

He adds that people with MS may also have trouble with learning and planning or memory, but this usually occurs later in the disease.

"Unfortunately, over time, symptoms and disability tend to accumulate, which is why it's important to get an early diagnosis and treatment," Turner stresses.

What causes MS and how is it diagnosed?

Although it's believed genetic and environmental factors may both play a role, the exact cause of MS is still a bit of a mystery. And there is no single test to diagnose the condition.

However, MS is thought to cause the immune system to attack myelin, the protein covering the central nervous systems, which makes it harder for messages to get received, potentially causing problems with how a person walks, moves, eats and processes things.

"Many of the symptoms are present in other conditions too," says Turner, "which means it can be difficult to diagnose."

Methods of diagnosis include blood tests (which can help rule out other conditions); MRI scans (which can reveal typical lesions on the spinal cord or brain); evoked potential tests (measuring electrical activity in the nervous system) and lumbar puncture (to reveal abnormal immune activity).

"There are also different types of MS, such as relapsing and remitting (RRMS) and primary progressive MS (PPMS), which will determine the path of treatment," Turner adds. "For both diagnosis, prognosis and treatment, it is important to see a neurologist with a specialist interest in MS."

4 things not to say to someone with MS

People react in all sorts of ways when someone has a chronic illness. Whether you know someone who has had MS for a few months or for many years, there's a good chance they'll have received unsolicited advice or unhelpful comments from well-meaning friends and relatives at some point or other.

Grazina Berry, CEO of Overcoming MS, explains a few key phrases you should avoid saying to someone who has MS...

1. You don't look ill - you seem fine!

"The main thing for anyone who is a friend of someone with MS to bear in mind is that just because someone seems healthy or appears to be only slightly affected, how they feel can be a whole different matter.

"Many of the symptoms of MS are either invisible or if they are visible, may not always be apparent. Symptoms can take time to develop and can vary from person to person and over time - no two people who have MS will be affected identically."

2. You'll feel better if you tell people

"People also won't process an MS diagnosis in the same way, like any difficult news," says Berry. "Not everyone wishes to disclose their diagnosis straight away, or to everyone, especially in the workplace, and their decision is a personal one which should be respected."

3. At least it isn't terminal

"Living with MS requires constant and long-term changes to one's lifestyle to help manage symptoms. Therefore, thinking that living with MS can be made easier solely by thinking positively, is very much wishful thinking," says Berry.

"Instead, talk to the person openly and be accommodating to their needs, like making sure there is access to a toilet, or finding a less physical activity to do together. "

4. You'll feel less tired once you're out and about

"MS fatigue isn't the same as being tired from a bad night's sleep and shouldn't be played down," says Berry. "If you're a friend of someone who has MS then simply be there, be present, and offer empathy instead of advice.

"Don't stop inviting them to social occasions, even if they aren't always able to make it due to their symptoms, and don't make them feel bad about cancelled plans," Berry adds. "Being someone to talk to can go a long way towards crucially making someone feel less isolated."