Skip to navigation Skip to content

Understanding MS

Discover more about Multiple Sclerosis.

Información en español

Bienvenidos a este su centro de información sobre la esclerosis múltiple (EM).



Back to top

What is multiple sclerosis?

Multiple sclerosis is a chronic, unpredictable disease of the central nervous system (CNS), which is made up of the brain, spinal cord and optic nerves. It is thought to be an immune-mediated disorder, in which the immune system incorrectly attacks healthy tissue in the CNS.

In multiple sclerosis, damage in the central nervous system (CNS) interferes with the transmission of nerve signals between the brain and spinal cord and other parts of the body.

Most people are diagnosed between the ages of 20 and 50, although children and older adults may develop it. 

Back to top

Who gets MS?

Anyone may develop MS but there are some patterns. More than two to three times as many women as men develop MS and this gender difference has been increasing over the past 50 years. Studies suggest that genetic factors increase the risk of developing MS, but there is no evidence that MS is directly inherited. Environmental factors, such as low Vitamin D and cigarette smoking have also been shown to increase the risk of MS. MS occurs in most ethnic groups, including African-Americans, Asians and Hispanics/Latinos, but is most common in Caucasians of northern European ancestry.
Back to top

How many people have MS?

Worldwide, more than 2.3 million people have a diagnosis of MS. In the United States a recently completed prevalence study, funded by the National MS Society, has estimated that nearly 1 million people over the age of 18 live with a diagnosis of MS.  In 2016, the 21st Century Cures Act was signed into law, authorizing the Centers for Disease Control and Prevention (CDC) to create a National Neurological Conditions Surveillance System (NNCSS) to collect data on neurologic conditions to improve research and public health data on these conditions. The NNCSS received its first 5-year period of funding starting in fiscal year 2019 and the Society will ask Congress to continue its $5 million investment in this important System in fiscal year 2020.

The CDC is using multiple sclerosis and Parkinson’s disease, as demonstration projects to inform the creation of the Surveillance system and help the CDC determine the appropriate methodologies to use and identify areas of biggest impact. Using innovative methods and complex data sources, the CDC will gather information for these diseases and use similar methods to extend the NNCSS to other neurologic disease conditions. 

This system will be informed by the Society’s prevalence initiative, a four-year study that used millions of health records to get a more accurate count of the number of people in the US living with MS.  The study showed that nearly 1 million people in the United State live with MS - more than twice the number previously thought.

Back to top

What are the different types of MS?

While there is no way to predict with any certainty how MS will progress, four basic disease courses have been defined:
  • Clinically isolated syndrome-first episode of neurologic symptoms caused by inflammation and demyelination in the central nervous system.
  • Relapsing-remitting MS -characterized by periods of relapses (new symptoms or a new worsening of older symptoms also called attacks or exacerbations) that subside, with full or partial recovery, and no disease progression (worsening) between attacks.
  • Secondary progressive MS- follows relapsing-remitting MS in some people and is characterized by a more progressive course, with or without relapses or new MRI activity.
  • Primary progressive MS is characterized by a gradual but steady progression of disability from the onset of symptoms, with few or no relapses or remissions.
 Read more about the types of MS.
Back to top

What are the typical symptoms of MS?

Symptoms of MS are unpredictable and vary in type and severity from one person to another and in the same person over time. Symptoms may disappear or remit completely, or they may persist and may worsen over time.

The most common symptoms of MS include fatigue, numbness and tingling, blurred vision, double vision, weakness, poor coordination, imbalance, pain, depression and problems with memory and concentration. Less commonly MS may cause tremor, paralysis and blindness.
Back to top

What causes the symptoms?

Symptoms of MS occur because of damage within the central nervous system (brain, spinal cord and visual nerves). Inflammation from the MS immune process causes damage to myelin, (the protective insulation surrounding nerve fibers), oligodendrocytes (cells that make CNS myelin) and also the underlying nerve fibers. Symptoms may be temporary or permanent and may worsen over time.

Back to top

Does MS always cause paralysis?

No. Moreover, the majority of people with MS do not become severely disabled. Two-thirds of people who have MS remain able to walk, though many will need an aid, such as a cane or crutches, and some will use a scooter or wheelchair because of fatigue, weakness, balance problems, or to assist with conserving energy. 
Back to top

Is MS fatal?

Life expectancy has increased over time. We believe this is due to treatment breakthroughs, improved healthcare and lifestyle changes. Research indicates that the average life expectancy of people with MS is about seven years less than the general population because of disease complications or other medical conditions. Many of these complications are preventable or manageable. Attention to overall health and wellness can help reduce the risk of other medical conditions, such as heart disease and stroke, that can contribute to a shortened life expectancy. In very rare instances, MS can progress rapidly from disease onset and can be fatal.

Back to top

Can MS be cured?

Not yet. There are now FDA-approved medications that have been shown to "modify" the course of MS by limiting new areas of damage in the CNS, reducing the number of relapses and delaying progression of disability. In addition, many therapeutic and technological advances are helping with more effective symptom management. Advances in treating and understanding MS are made every year, hopefully moving research closer to identifying a cure.

Back to top

What can be done about MS now?

If you have been diagnosed with MS, the National MS Society recommends you consider treatment with one of the FDA-approved "disease-modifying" drugs as soon as possible following the definite diagnosis of MS with active or relapsing disease. These medications help to reduce the frequency and severity of MS attacks, the number of new lesions in the CNS and may slow the progression of disability. These medications are approved for relapsing forms of multiple sclerosis, which include clinically isolated syndrome, relapsing-remitting disease (RRMS) and active secondary progressive disease (SPMS with relapses).

In addition to these medications that address the disease process, there are many medications and other strategies to manage MS symptoms. You should consult a knowledgeable MS care provider to develop a comprehensive plan to manage your MS.
Back to top

Why is early treatment important?

Early damage in the CNS can occur even before you are experiencing any symptoms. Studies show that the best chance for reducing long-term disability is during the early relapsing phase of the disease, which is characterized by inflammation. Given that the medications currently available all primarily target inflammation, early and ongoing treatment helps to minimize this inflammation and also reduces damage to nerve fibers (axons) and loss of brain tissue.
Back to top

Why is MS so difficult to diagnose?

Diagnosing MS can be a challenging process. In early MS, symptoms may be non-specific and suggestive of several disorders of the nervous system. Early symptoms that come and go may be ignored. While no single laboratory test is yet available to prove or rule out MS, magnetic resonance imaging (MRI) is a great help in reaching a definitive diagnosis.  Diagnostic criteria that incorporate MRI findings and spinal fluid analysis have been developed and revised by experts in the field to help providers make an accurate and timely diagnosis.


The National MS Society is Here to Help

Newly Diagnosed

If you or someone close to you has recently been diagnosed, access our MS information and resources.

Start Here

Start Here

YOU have power to change a life!

People with MS need vital services, advocacy - and a cure.

Every dollar counts.

© 2023 The National Multiple Sclerosis Society is a tax exempt 501(c)3 nonprofit organization. Its Identification Number (EIN) is 13-5661935.