Multiple sclerosis (MS) is one of the most widespread disabling neurological conditions of young adults around the world. It affects almost 1 million people in the United States, and about 2.9 million people worldwide.
There are relapsing-remitting and progressive types of MS, but the course is rarely predictable. Researchers still don’t fully understand the cause of MS or why the rate of progression is so difficult to determine.
There’s no national or global registry for new MS cases. Known figures are only estimates.
Findings from the National MS Society estimate that nearly 1 million people in the United States are living with MS.
An estimated 2.9 million people live with MS worldwide. An estimated 200 new cases are diagnosed each week in the United States, according to the most recent data from the MS Discovery Forum.
Rates of MS are usually higher further from the equator. Some researchers consider vitamin D deficiency as a possible explanation for this.
According to the
Based on the most recent information available, the United States into four regions with the following prevalence:
- Northeast: an estimated 377 cases per 100,000 people
- Midwest: an estimated 353 cases per 100,000 people
- South: an estimated 277 cases per 100,000 people
- West: an estimated 277 cases 100,000 people
People of Northern European descent have the highest risk of developing MS, no matter where they live. Meanwhile, the lowest risk appears to be among people of Native American, African, and Asian descent.
Children can get MS, too. Fewer than 5,000 children and teens currently live with MS in the United States, and around 30,000 children live with it worldwide, according to the National MS Society.
Based on the most recent data available as of 2025. (Illustration by Bailey Mariner)
Sex is a risk factor for developing MS. MS is
MS is not an inherited disorder. However, first-degree relatives of someone with MS have a 2% to 5% risk of developing MS. Children of parents with MS may have a
In the case of identical twins, if one twin has MS, there’s a 20% to 30% chance that the other twin will also have the disease.
Researchers and neurologists still can’t say with certainty what causes MS. The ultimate cause of MS is damage to myelin, nerve fibers, and neurons in the brain and spinal cord. Together these make up the central nervous system.
Researchers speculate that a combination of genetic and environmental factors is at play, but it’s still not fully understood how.
The relationship between the immune system and the brain may be considered a culprit. Researchers suggest the immune system may mistake typical brain cells for foreign ones.
One thing the MS community knows for certain is that the disease is not contagious.
Learn more about MS causes and risk factors.
Some types of MS are more common than others.
Clinically isolated syndrome (CIS)
CIS is considered to be one course of MS, but it may or may not progress to MS.
People who are at high risk of developing MS are found to have lesions on the brain that can be detected through magnetic resonance imaging (MRI). Those with brain lesions have a 60% to 80% chance of receiving an MS diagnosis within a few years, according to the National MS Society.
Meanwhile, people at low risk don’t have MRI-detected brain lesions. They have a 20% chance of receiving an MS diagnosis in the same amount of time.
Relapsing-remitting MS (RRMS)
RRMS is characterized by clearly defined relapses of increased disease activity and worsening symptoms. These are followed by remissions when the disease doesn’t progress.
Symptoms may improve or disappear during remission. Approximately 85% of people receive a diagnosis of RRMS at first, according to the National MS Society.
Secondary progressive MS (SPMS)
SPMS can follow an initial RRMS diagnosis. Disability may gradually increase as the disease progresses, with or without evidence of relapse or changes in an MRI scan. Occasional relapses may occur, as well as periods of stability.
Without treatment, about
While these are the most recent statistics available, advances in a disease-modifying therapy (DMT) for MS may actually slow down the progression. However, it is too soon to tell by how much DMT alters the progression to SPMS.
Primary progressive MS (PPMS)
PPMS is diagnosed in about
A high percentage of MS cases do not progress.
A small number of cases may fit into a designation of “benign MS.” However, the prevalence and criteria for benign MS are considered controversial. This diagnosis is often based on the Expanded Disability Status Scale (EDSS), which measures MS disability.
Despite a lack of noticeable disability, people with benign MS may have ongoing CNS damage from the disease.
Learn more about the types of MS.
Multiple sclerosis (MS) affects almost 1 million people in the United States. Worldwide, there are around 2.9 million people with the condition.
MS is more common in females than males. It is not an inherited condition, but the risk of developing MS may be slightly greater if you have a first-degree relative with the condition.
At the time of diagnosis, most people have relapsing-remitting MS. Other types include primary progressive MS, secondary progressive MS, and clinically isolated MS.
Contact your doctor if you have concerns about MS. They can provide more information about the risk factors for the condition. They may order tests if you have symptoms of MS, and they can advise on a suitable treatment plan after confirming the diagnosis.
