Multiple sclerosis

Learn about multiple
sclerosis and what we’re
doing to help

What is multiple sclerosis?

Multiple sclerosis (MS) is a condition that affects the brain, spinal cord and optic (eye) nerve. In people with MS, the coating that protects the nerves – called myelin – is damaged. This causes symptoms that can affect how you think, move and feel.

It’s estimated that MS affects approximately 2.3 million people around the world.

What are the main types of MS?

Relapsing-remitting MS (RRMS)

Around 85% of people with MS have RRMS. This means that symptoms flare-up from time to time (relapses) and can cause problems with everyday life. In between relapses, the person will experience periods of recovery – either partially or completely (remission). Our main area of research focuses on RRMS

Primary progressive MS (PPMS)

Around 10-15% of people with MS have PPMS. Unlike RRMS, the symptoms of MS tend not to come and go (relapse and remit), but rather get steadily worse (progress). The rate at which this happens can be different for each person

Secondary progressive MS (SPMS)

This tends to follow on from RRMS, at a stage when, rather than having symptoms flaring up from time to time (relapses) followed by periods of recovery (remission), disability keeps on increasing

What are the signs and symptoms of MS?

Symptoms of MS can vary a lot from one person to the next and are often quite subtle, meaning that they can’t always be seen by the outside world. The following are the most common symptoms:

What causes MS?

The exact cause of MS is unknown, but it’s believed that a number of factors are involved:

The immune system

The body’s immune system doesn’t respond as it should in people with MS, leading to inflammation and damage of the brain and spinal cord.


Certain viruses and bacteria are being researched to find out if they can play a part in causing MS.

Where you live

The risk of developing MS may be related to the amount of sunlight a person is exposed to (a natural source of vitamin D), which varies depending on where they live in the world.

Family history

MS is much more common if you have a direct relative who has it, such as a parent or sibling.

Who does MS affect?

People tend to be diagnosed with MS between the ages of 20 and 45 but it can also affect children. Around 3-5% of all MS cases begin in childhood. It is three times more common in people assigned female at birth than those assigned male at birth. In the United States, black and/or African-Americans have 47% increased risk for MS compared to white people.

Our MS research

We’re currently focusing our research on finding out if investigational drugs may potentially slow the progress of MS by reversing or possibly repairing the damage and inflammation that the disease causes to the myelin.

We’re also conducting trials in drugs currently approved for adults to see if they’re suitable for children with MS, as well as looking to increase the ways in which treatments are given. See our section on clinical trials in children.

What could a Biogen MS trial involve?

Before you join a trial, the trial team will first confirm your eligibility with some health assessments. Then, if you’re eligible and choose to take part in an MS trial, you’ll need to attend several appointments so that we can closely monitor your health and condition with health assessments such as:

Walking assessments

These are done to assess your walking ability, for example, to see how far you can walk, and how you get on when turning around while walking.


These are to assess how well you’re thinking and performing daily activities, as well as how you’re feeling, in terms of your mental health and wellbeing.

MRI scans

Magnetic resonance imaging (MRI) uses a magenetic field and computer-generated radio waves to create detailed images of the organs and tissues in the body, including 3D images that can be viewed from different angles.

Information from digital

In some MS trials we’re testing sensors that send us information between visits to help us learn more about how the investigational drugs impacts MS.

Other assessments will be involved. A full list of these, and all other requirements around taking part in a trial, would be fully discussed with you before you made a decision about whether to join a trial or not.

Depending on the assessments required at each visit, you may be able to complete some of them at home or over the phone.

And remember, if you join a clinical trial, there are many rules and regulations in place to protect your rights, safety, welfare, and personal data.

What is the role of a caregiver in an MS clinical trial?

Someone who cares for you, for example, a partner, sibling, other family member, close friend, or professional caregiver, may take part in the trial with you. This may be to help you get to and from your appointments and support you throughout the trial. Or, they might be asked to help monitor any changes in your condition and report them to us. Visit our section on caregivers for more information about this role.

How can I get involved?

To find new treatment options for MS, we must first test investigational drugs in clinical trials. In the same way that diseases like MS can impact groups of people in different ways, how medicine works in the body can also vary for different groups of people. That’s why it’s so important that a diverse range of people take part in clinical trials.

You can learn more about the importance of diversity in clinical trials, and Biogen’s efforts to make an impact, here.

Recruiting multiple sclerosis trials:

Click to view full study details including trial locations.

Help and resources

There are organizations that offer information and support for people living with MS and their families. Below are some groups where you can find out more about MS, connect with others, or learn about the latest research. Remember, this list of organizations does not imply an endorsement from Biogen or the listed organization.