Multiple sclerosis overview
Fact-checked by Multiple sclerosis (MS) is a chronic neurological disease in which the immune system mistakenly attacks the myelin sheath, a protective coating around nerve fibers.
This causes damage that disrupts the transmission of nerve signals, leading to a wide range of physical, sensory, and cognitive problems. Common MS symptoms include fatigue, pain, movement difficulties, vision problems, and bladder or bowel dysfunction.
There are four types of MS, classified by how its symptoms appear and progress over time. While there is no cure, many treatments are available that can slow MS disease progression, ease symptoms, and help people maintain their quality of life.
What is MS?
MS is an autoimmune disease, meaning the immune system mistakenly attacks the body’s own cells and tissues. In MS, these immune attacks target myelin within the central nervous system (CNS), including the brain, spinal cord, and optic nerve.
As myelin is damaged and destroyed — a process known as demyelination — nerve signaling becomes less efficient. Over time, this may also affect the nerve fibers themselves, leading to nerve damage.
While the nervous system can repair damaged or lost myelin under normal circumstances, attempts to repair myelin are often incomplete in MS, leading to the formation of lesions that are visible on imaging scans. Disease symptoms often depend on which CNS regions are affected by these lesions.
MS is most commonly diagnosed between ages 20 and 40. It is estimated to affect around 1 million people in the U.S., and 2.8 million people worldwide.
What are the types of MS?
There are four main types of MS, and these are broadly classified based on patterns of symptom activity and disease progression:
- Clinically isolated syndrome (CIS): A first episode of neurological symptoms suggestive of MS. On its own, this single event is not enough to diagnose MS, but additional signs of disease activity may eventually lead to an MS diagnosis.
- Relapsing-remitting MS (RRMS): The most common type of MS, accounting for about 85% of newly diagnosed cases. RRMS is characterized by periods of new or worsening symptoms, called relapses, followed by periods of partial or complete recovery (remission).
- Secondary progressive MS (SPMS): A stage that may follow RRMS, marked by a gradual worsening of neurological symptoms, even in the absence of relapses.
- Primary progressive MS (PPMS): Affects about 15% of newly diagnosed MS patients. People with PPMS experience a steady decline in neurological function from disease onset, regardless of relapse activity.
Other rare forms of MS or MS-like conditions also exist.
What causes MS?
The exact causes of MS remain unknown, but research suggests the disease develops from a combination of genetic and environmental factors. Known risk factors include:
- Genetics: MS is not inherited, but having a family member with MS increases the risk of developing the condition. Also, more than 200 genetic variants have been identified as possibly contributing to MS development. The strongest genetic risk factor for MS is a variant in the immune-related gene HLA-DRB1.
- Infections: Some infections have been linked to MS. Prior infection with the Epstein–Barr virus (EBV), in particular, is considered a major risk factor and appears to be necessary, though not sufficient, for MS to develop.
- Other autoimmune diseases: Conditions such as type 1 diabetes, inflammatory bowel disease, thyroid disorders, and psoriasis are linked to an increased risk of MS.
- Geography: MS is more common in regions farther from the equator, including northern Europe, the northern U.S., and Canada.
- Vitamin D: Low vitamin D levels are consistently associated with increased MS risk, possibly due to the vitamin’s effects on the immune system.
- Smoking: People who have ever smoked or been exposed to secondhand smoke are at an increased risk of developing MS. Smoking is also associated with worse outcomes in MS patients.
- Obesity: People who are obese are at increased risk of MS, especially when obesity starts in childhood and adolescence.
- Demographic factors: MS is about three times more common among women than men, and is most often diagnosed between ages 20 and 40. It is also most common in Black and non-Hispanic white populations.
Ongoing research is focused on better understanding possible MS causes and risk factors.
What are the symptoms of MS?
MS symptoms vary widely depending on which areas of the nervous system are affected and how much damage has occurred. Disease severity and progression also differ from person to person, meaning everyone with MS will have a different experience.
Early signs
A concrete list of early signs of MS does not exist because symptoms can vary widely. In many people, early symptoms overlap with common MS symptoms, but may be mild, intermittent, or mistaken for other conditions.
People who are concerned they may be experiencing early symptoms of the disease are advised to speak with a healthcare provider and keep a record of when symptoms occur, how long they last, and how severe they are.
Only a trained medical professional, usually a neurologist, can confirm an MS diagnosis.
Common symptoms
The most common symptoms of MS include:
- movement problems
- fatigue
- pain and other abnormal sensations
- changes in bladder, bowel, or sexual function
- cognitive problems
- depression and other mental health issues
- vision problems
Not everyone with MS will experience all of these symptoms, and their severity can vary widely. In some people, symptoms will come and go, while in others they gradually worsen over time as the disease progresses.
How is MS diagnosed?
There is no single test to diagnose MS. Instead, doctors rely on a series of physical and neurological examinations that show inflammation and damage consistent with MS, while helping to rule out other conditions.
These may include:
- a detailed medical history and neurological examination
- MRI scans, used to detect inflammation and damage in the brain and spinal cord
- evoked potential tests, to assess changes in nerve cell signal transmission
- a spinal tap, also known as a lumbar puncture, to identify signs of inflammation in the CNS
- vision tests, to identify signs of inflammation in the optic nerves, which carry information between the eyes and the brain.
- blood tests, to exclude other conditions and measure disease biomarkers
The McDonald Criteria are a set of diagnostic guidelines that doctors use to determine whether a person’s signs and symptoms warrant an MS diagnosis.
Is MS treatable?
While no cure currently exists for MS, many treatments are available to help manage the disease, and many more experimental therapies for MS are being developed.
Most of these therapies aim to suppress the immune system in order to reduce inflammation and prevent further CNS damage. Others work to ease specific symptoms and help patients lead as normal a life as possible.
Because MS can affect a range of physical, sensory, and cognitive functions, care usually involves a multidisciplinary MS care team, which selects the best MS treatment combination based on each person’s individual situation.
Medications currently used to treat MS fall into three main categories:
| Therapy | Purpose |
|---|---|
| Disease-modifying therapies | Prevent disease activity in the form of relapses and new lesions and slow the accumulation of disability |
| Relapse management therapies | Shorten the duration and reduce the severity of disease relapses |
| Symptomatic treatments | Address specific symptoms, such as pain, fatigue, or bladder issues |
What is the life expectancy for people with MS?
The prognosis for people living with MS has improved substantially in recent decades. The average MS life expectancy is estimated to be about five to 10 years shorter than that of the general population, and this gap is closing as diagnosis and care continue to improve.
Today, many people experience slow disease progression, and about two-thirds retain the ability to walk 20 years after diagnosis, although some may require assistive devices to do so.
While the course of the disease is influenced by each person’s individual risk factors and general health, MS prognosis is generally better for people with relapsing forms of MS than for those with PPMS.
What other conditions could MS be mistaken for?
MS shares many signs and symptoms with other neurodegenerative or autoimmune conditions, especially in the early stages, which may lead to misdiagnosis. These similar conditions to MS include:
- Amyotrophic lateral sclerosis (ALS): a progressive neurodegenerative disease that affects motor neurons, the specialized nerve cells that control voluntary movement
- Parkinson’s disease (PD): a neurodegenerative condition that affects the nerve cells in the brain that release a signaling molecule called dopamine
- Myasthenia gravis (MG): an autoimmune neuromuscular condition that affects the way nerve and muscle cells communicate
As in MS, all of these conditions can lead to muscle weakness and movement problems, but they differ in several other ways.
| Disease | Symptoms | Diagnosis | Progression |
|---|---|---|---|
| MS | Abnormal sensations, spasticity, bladder and bowel complications, vision problems | Most commonly diagnosed in people ages 20 to 40 | Can significantly impact many facets of life, but does not leave patients completely debilitated |
| ALS | Profound muscle weakness that ultimately results in severe problems with breathing, swallowing, and speech | Symptoms typically begin around the ages of 55 to 75 | Symptoms worsen over time, leading to complete debilitation and paralysis |
| PD | Resting tremor, slowness of movement, muscle stiffness, fatigue, cognitive changes | Generally begins later in life, with most cases beginning around age 60 | Is not fatal, but can put substantial strain on the body |
| MG | Droopy eyelids, double vision, slurred speech, weakness in the arms and legs | Most commonly affects women under the age of 40 and men over the age of 60 | Symptoms may come and go, but generally worsen over time |
What are some other diseases related to MS?
Besides MS, several other neurological conditions are also caused by an inflammatory attack that damages the myelin sheath. These are collectively called demyelinating diseases, and include:
- Transverse myelitis: Inflammation and myelin damage occur in the spinal cord. This can be a symptom of MS or occur on its own, often after an infection. Symptoms include limb weakness, abnormal sensations, pain, and bladder or bowel issues.
- Acute disseminated encephalomyelitis (ADEM): Usually involves a single attack that causes myelin damage in the brain, spinal cord, or optic nerve, often triggered by an infection. Symptoms overlap with MS, but may additionally include fever, seizures, confusion and nausea or vomiting, and unconsciousness. ADEM is more common in children than adults.
- Neuromyelitis optica spectrum disorder (NMOSD): A progressive autoimmune disease that usually causes inflammation and demyelination in the optic nerve or spinal cord, leading to issues with vision and movement. As a relapsing-remitting disease, NMOSD attacks can look similar to MS, but they are generally more severe.
While these conditions resemble MS in some ways, doctors can usually distinguish them based on the location and number of lesions on MRI scans, symptoms, and specific disease biomarkers.
Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
