When doctors talk about disease progression, they usually break it down into stages. MS can also be divided into stages. But they aren’t quite like cancer stages that have a clear progression.

Instead, your disease progression and stage depend on the type of MS you have, your symptoms, and how much they affect your daily life — for instance, whether or not they cause disability.

This article will cover how MS progresses, the stages of disability, and life expectancy. We’ll also look at whether highly effective disease-modifying therapies (HE-DMTs) can help slow disease worsening and improve the prognosis (outlook).

How Does Multiple Sclerosis Progress?

MS generally progresses in two different ways. The form of MS you have usually affects how your disease worsens.

Relapse-associated worsening (RAW) occurs when you can’t completely recover from a relapse. A relapse refers to a time when your MS symptoms “flare” or get worse. A relapse is also known as an exacerbation.

MS can progress both with and without relapses.

At first, your body is able to recover from the inflammation and attacks on your central nervous system (CNS). As damage builds up over time, it becomes harder to recover and reach remission. People with relapsing-remitting MS (RRMS) usually progress because of RAW.

The second way MS progresses is by progression independent of relapse activity (PIRA). This means your MS symptoms keep getting worse — even without relapses or flare-ups.

PIRA is usually responsible for progression in people with nonrelapsing MS. This includes:

• Primary progressive MS (PPMS)
• Secondary progressive MS (SPMS)

However, one large study of people with MS found that those with RRMS also experience PIRA. It’s just less common than in PPMS and SPMS.

Up to half of all worsening disability wasn’t directly caused by relapses. This means that progression happens even without MS flare-ups for many people.

What Happens in Your Body When Multiple Sclerosis Progresses?

MS is a neurological condition that develops when your immune system attacks your body. Specifically, MS is an autoimmune disease that attacks your CNS — which includes your brain, optic nerve, and spinal cord.

Immune cells damage the fatty coating on your nerve cells called the myelin sheath. Myelin protects your nerve cells and helps them send signals to each other.

Lesions form in areas along the nerve with demyelination. Lesions are scars from CNS damage, meaning the myelin sheath is missing.

Over time, damage to the CNS affects how well your nerves communicate with the rest of your body. The location and severity of the damage affects your symptoms and disease progression.

Doctors usually measure progression using the Expanded Disability Status Scale, which measures how MS affects your daily life.

Doctors can see lesions on the brain and spinal cord with MRI scans. Your lesions can look different depending on the type of MS and inflammation you have.

For example, lesions from PIRA look different than those caused by relapses. Researchers are still looking into why these lesions are different and what it means for MS progression.

How Do Doctors Measure MS Disability and Progression?

Most studies looking at MS progression use the Expanded Disability Status Scale (EDSS) to measure disability. The EDSS looks at how much MS affects your daily life and causes disability.

To get your EDSS score, your doctor will ask questions about your symptoms. They’ll try to find out about changes in:

• Muscle strength in your arms and legs
• Coordination and balance
• Bowel and bladder habits
• Memory and cognitive skills (how well you think)
• Problems with any uncontrollable hand or eye movements

The EDSS is measured on a scale of 0 through 10. The higher your score, the more MS affects you and the more disability you have.

As MS progresses, your EDSS score will increase. Generally speaking, your MS is progressing if, over the course of six months:

• Your EDSS score increases by 1.0 point if your baseline is less than or equal to 5.5
• Your EDSS score increases by 0.5 points if your baseline is greater than or equal to 6.0

For example, you may have an EDSS score of 5.0. This means you have significant disability that affects your daily activities. However, you can walk shorter distances without a cane or walker to help.

After six months, you need a mobility aid to help you walk. You also can only walk around 300 feet at a time, and you may need to stop for rest. Your new EDSS score is now a 6.0.

In this example, your doctor would consider your MS as progressing. Your symptoms got worse over a period of six months by at least one point in your EDSS score.

How Does Multiple Sclerosis Affect Life Expectancy?

MS life expectancy is often close to typical life expectancy, though studies suggest MS may shorten lifespan by about two to seven years. New treatments have helped improve life expectancy in recent years.

Disease-modifying therapies — especially newer medications known as highly effective DMTs — can help slow MS progression.

When MS enters its progressive phase, your symptoms may continue worsening over time. MS itself isn’t usually the cause of death in people with the condition. Instead, people tend to have other health problems, like:

• Lung infections and breathing conditions
• Heart and vascular diseases
• Urinary tract infections
• Infections that travel into the bloodstream

How Do New MS Treatments Slow Disease Progression?

The mainstay treatment for relapsing MS is DMTs. These medications don’t just treat MS symptoms — they may also help slow disease progression.

A large study of people with MS compared people who used DMTs to those who took a placebo (inactive substance).

People treated with DMTs took 12.5 years to reach an EDSS score of 4. The people who took the placebo reached the same score in 9 years. This means that DMTs delayed disease progression by 3.5 years.

People with RRMS who take HE-DMTs have fewer relapses and less CNS damage. Some can even improve their EDSS scores with the right treatment. Other people see their EDSS scores stay stable without symptom worsening.

Since HE-DMTs are relatively new, we don’t know exactly how they affect disease course and life expectancy yet. Some reports suggest that DMTs can help people with MS live longer.

However, researchers aren’t sure if this is because of DMT treatment or other lifestyle choices. More studies are looking into how these medications help slow progression and improve life expectancy.

Talk To Your Doctor About Your MS Progression and Treatment

Each person’s multiple sclerosis progression timeline is different. Talk with your neurologist about how well your MS treatment plan is working for you to slow disease progression. They can also discuss your individual risks for progression and what else you can do to improve your prognosis.

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