Multiple Sclerosis Facts

Was this helpful?
brain and nerve cell illustration

What is multiple sclerosis?

Multiple sclerosis (MS) is a chronic central nervous system (CNS) disorder affecting brain, spinal cord, and optic nerve function. MS is considered an autoimmune-mediated disease. Experts have put forth several possible MS causes, but it is likely a combination of factors.

With MS, the immune system attacks the protective myelin sheath of nerve fibers, which disrupts nerve impulses within the brain, and between the brain and body. MS symptoms occur with increasing loss of myelin (demyelination) and damage to the fibers and cells themselves, creating scleroses (scars, lesions) in the CNS. Progressive nerve loss leads to disability.

Depending on the location of scars, symptoms can include:

  • Blurred vision

  • Bowel and bladder problems

  • Dizziness and loss of balance

  • Fatigue

  • Pain

  • Poor concentration and memory

  • Tingling or prickling sensations

  • Walking difficulties

  • Weakness and muscle spasticity

What are the different forms of multiple sclerosis?

Doctors base their diagnosis of different MS types, or disease courses, on patient symptoms and clinical evidence of brain lesions by MRI (magnetic resonance imaging).

Disease courses include:

  • Clinically isolated syndrome: A patient is diagnosed with CIS upon the first episode of MS symptoms lasting at least 24 hours, with or without MS-like brain lesions on MRI. A person with lesions is more likely to develop MS.

  • Relapsing-remitting multiple sclerosis: Affecting 80 to 85% of patients initially diagnosed with MS, periods of acute symptom flares (relapses) and disease remission characterize RRMS.

  • Secondary-progressive multiple sclerosis: SPMS develops after RRMS, usually within 35 years of initial diagnosis, but the transition occurs earlier when RRMS is not well controlled or treated. It is marked by a significant increase in disability. MS symptoms are more severe and debilitating, with or without periods of relapse and remission.

  • Primary-progressive multiple sclerosis: Affecting 5 to 15% of patients at initial diagnosis, steadily worsening MS symptoms and increasing disability characterize PPMS. It does not follow the more classic RRMS pattern with acute exacerbations.

As of 2014, clinicians replaced the former disease course known as progressive-relapsing multiple sclerosis with the PPMS classification.

Who gets multiple sclerosis?

Recent research estimates 1 million people in the United States have MS. Most people are 20 to 40 years old when symptoms start, but younger and older people can develop it. The primary progressive form of MS most often occurs in people older than 40.

Data on the exact incidence of MS in specific populations is lacking because MS is not common—an individual’s risk of developing MS is 1 in 750 to 1,000. However, research studies highlight some significant factors for who gets MS:

  • Family history: People who have a first-degree family member (parent or sibling) with MS have a 20- to 40-fold higher risk of developing it compared to individuals without an affected first-degree relative.

  • Gender: Women (biologically female) have a three-fold higher risk of developing MS than men.

  • Ethnicity: MS affects White Americans more than Black and Hispanic Americans in the United States.

  • Location: MS prevalence increases with distance from the equator, although the reason for this geographic difference is not clear.

Can you die from multiple sclerosis?

Although MS symptoms and disability are not a direct cause, complications from the disease can be fatal. Overall, multiple sclerosis life expectancy is shortened by 7 to 14 years compared to people without the disease. About 50% of MS patients die from MS-related causes, according to a review of many studies. A recent study from Norway finds that people with MS have three-fold higher mortality rate than the general population.

New studies of large patient populations are necessary to understand factors affecting MS prognosis and survival, including disease and disability severity, age at transition from RRMS to SPMS, treatment, symptom control, and coexisting conditions, among other factors. In particular, smoking and vascular conditions increase disability and mortality risk.

What are some conditions related to multiple sclerosis?

Conditions related to MS include:

  • Acute disseminated encephalomyelitis: A rare but short-lived condition marked by severe inflammation that causes demyelination and MS symptoms. It oftentimes follows a bacterial or viral infection.

  • Balo’s disease: A rare and rapidly progressive disease with a different pattern of brain demyelination than MS; may develop shortly after an infection.

  • HTLV-I associated myelopathy: A progressive spinal cord disease marked by leg weakness and spasticity and other symptoms; occurs in about 2% of people infected with HTLV-1 (human T-cell leukemia virus type 1).

  • Neuromyelitis optica: A relapsing-remitting disease that targets the optic nerve, spinal cord, and sometimes the brain. An autoimmune-mediated attack damages specific nervous system cells and causes their demyelination.

  • Schilder's disease: A rare and progressive disorder with demyelination of the central nervous system and MS symptoms. Schilder’s is a variant of MS that often follows an infection.  

  • Transverse myelitis: A rare neurologic condition marked by inflammation and demyelination across one level of the spinal cord. It often develops after an infection.

How does multiple sclerosis affect quality of life?

The unpredictable nature and disability of MS makes living with the disease difficult. Health-related quality of life (HRQoL) represents the degree of impact of physical and mental well-being, treatment strategies, and disability on quality of life for people with MS. It is based on patients’ answers to a standardized MS questionnaire. MS reduces HRQoL values compared to the general population.

Not surprisingly, disability is the strongest factor for lower values, according to a Canadian study on patients with relapsing MS. Patient-reported depression, anxiety, fatigue, and coexisting medical conditions (in this order) also have a negative impact.

MS-caused disabilities and conditions associated with lower quality of life include:

  • Cognitive problems including poor concentration and problem solving

  • Fatigue, which is tied to depression

  • Inability to walk unassisted (e.g., with a cane)

  • Pain, which may be due to causes other than MS, such as arthritis

What causes multiple sclerosis?

Immune-mediated inflammation and destruction of myelin, nerve fibers, and neurons cause MS symptoms and disability. MS experts do not know exactly how the immune system attacks the nervous system, but breakdown of the blood-brain barrier plays an important role.

A combination of factors is thought to increase the risk for developing MS including:

  • Genetic factors including chance variations in some 200 different genes linked to an increased risk of MS. The identical twin of a sibling with MS has about a 30% chance of developing it. Specific sequences in HLA-DRB1 and IL7R genes are strong risk factors.

  • Infectious diseases including prior infection with Epstein-Barr virus

  • Environmental factors including increasing distance from equator, low vitamin D levels in the blood, smoking, and obesity

In general, the most widely held view is that a non-genetic factor, such as an infection, triggers the disease in a person genetically at risk for MS.

How are you diagnosed with multiple sclerosis?

There is no single or series of tests that return a ‘positive’ MS result. It is a clinical diagnosis, which means the neurologist diagnoses it after considering a variety of factors. A high likelihood or proof that a patient has MS involves a comprehensive neurologic evaluation, blood tests, MRI, and possibly cerebrospinal fluid analysis.

A formal MS diagnosis requires all these criteria:

  • Central nervous system damage in at least two separate areas

  • Damage at different points in time

  • Exclusion of other diagnoses, such as Lyme disease

What are common treatments for multiple sclerosis?

MS treatment centers on medications that modify the immune system to decrease disease activity and delay nerve damage and disability. Treatment typically occurs in stages depending on how quickly the disease progresses, as determined by MRI and patient symptoms and disability.

Specific treatment strategies, including which drug is prescribed when and for how long, depend on patient benefits and drug risks (side effects) as well as physician preference and clinical expertise.

Treatments include:

  • Medications for MS relapses including corticosteroids and plasma exchange in severe cases

  • Disease-modifying drugs including beta interferons, chemotherapy drugs, and several agents (monoclonal antibodies among others) that inhibit specific enzymes and immune cells to decrease MS disease activity

  • Therapies for symptoms and disabilities including medications, physical therapy, occupational therapy, and alternative therapies

  • Healthy living including physical and mental exercise, emotional support, not smoking, and a healthy diet, which may include vitamin D supplementation

Additional multiple sclerosis facts

As part of the 21st Century Cures Act, the Centers for Disease Control and Prevention is launching the National Neurological Conditions and Surveillance initiative to collect data on multiple sclerosis. A better understanding of MS causes and risk factors, including possible environmental and viral triggers, will help with prevention and cure strategies.

MS Awareness week occurs in March, and World MS Day is in May.

Was this helpful?
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 Jan 8
  1. Hersh CM, Fox RJ. Multiple Sclerosis. Cleveland Clinic Center for Continuing Education. April 2018.
  2. MS Prevalence. National Multiple Sclerosis Society.
  3. Related Conditions. National Multiple Sclerosis Society.
  4. Xia Z, White CC, Owen EK, et al. GEMS Project: A Platform to Investigate Multiple Sclerosis Risk.
  5. Lublin FD, Reingold SC, Cohen JA, et al. Defining the Clinical Course of Multiple Sclerosis; the 2013 revisions. Neurology. 2014;83(3):278–286.
  6. Scalfari A, Knappertz V, Cutter G, et al. Mortality in patients with multiple sclerosis. Neurology. 2013;81(2):184–192.
  7. Multiple Sclerosis: Hope Through Research. National Institute of Neurological Disorders and Stroke.
  8. Multiple Sclerosis. Genetics Home Reference.
  9. HTLV-1 associated myelopathy. Genetic and Rare Diseases Information Center, National Center for Advancing Translational Studies.
  10. Bøe Lunde HM, Assmus J, Myhr K-L, et al. Survival and cause of death in multiple sclerosis: a 60-year longitudinal population study. J Neurol Neurosurg Psychiatry. 2017;88(8):621–625.
  11. Moss BP, Rensel MR, and Hersh CM. Wellness and the Role of Comorbidities in Multiple Sclerosis. Neurotherapeutics. 2017;14(4):999–1017.
  12. Berrigan LI, Fisk JD, Patten SB, et al., and for the CIHR Team in the Epidemiology and Impact of Comorbidity on Multiple Sclerosis. Health-related quality of life in multiple sclerosis; direct and indirect effects of comorbidity. Neurology. 2016;86(15):1417–1424.  
  13. Project – National Neurological Conditions Surveillance System (NNCSS).

Explore Multiple Sclerosis
Recommended Reading
Next Up
Answers to Your Health Questions
Trending Videos