Connect with others who understand.

sign up log in
Resources
About MyMSTeam

Connect with others who understand.

sign up log in
Resources
About MyMSTeam

Clusters of MS and What That Might Mean

Posted on March 30, 2021
Medically reviewed by
Evelyn O. Berman, M.D.
Article written by
Amanda Agazio, Ph.D.

When many cases of multiple sclerosis (MS) occur in a certain area or within a distinct amount of time, it is sometimes referred to as a cluster of MS. Scientists have studied these clusters in an attempt to identify new causes or risk factors for MS. However, these studies have failed to produce any clear evidence for new risk factors associated with the disease.

Problems With the Cluster Analysis

One major problem with the analysis of MS clusters is the difficulty of comparing expected and reported incidence. Incidence is the number of new cases in a set period of time. To report increased incidence, or a cluster, experts need to know the expected incidence for that area. Understanding this number can be challenging because MS incidence can change with geography, gender, and ethnic group. When studying a cluster, there may not be a uniform population of other people with MS outside of the cluster for comparison.

Another problem with cluster analysis involves the diagnostic criteria for MS. It can be difficult to diagnose MS, as it shares symptoms with some other diseases. Cases of MS within a cluster may be inaccurately diagnosed and reported. For example, clusters of MS have been reported in the United States, thought to be associated with increased heavy metals in the environment. However, it is unclear whether heavy metal exposure can cause MS, although heavy metal exposure can cause neurological symptoms that are similar to those seen in MS. Without proper diagnosis by a neurologist, exposure to heavy metals may be misdiagnosed as MS.

Additionally, there is often a lag time between the first symptoms of MS and the diagnosis of MS. This lag creates the possibility of someone developing MS in one region but being diagnosed and included in a cluster study in a new region.

What Do We Know About Patterns of MS Diagnosis?

It is unclear whether clusters of MS are a valid phenomenon that occurs with the disease — what people may perceive as excessive case numbers may be normal rates of MS. There are some well-studied patterns associated with MS, including environmental factors and genetic factors associated with disease development.

Geographic and Environmental Factors

Scientists and epidemiologists have found a clear pattern with geography and the prevalence of MS. There is an observed gradient in MS prevalence with latitude, and more temperate regions further from the equator. For example, Northern Europe, the northern United States, Canada, Southern Australia, and New Zealand tend to have increased cases of MS.

The geographical differences in MS incidence may be due to environmental risk factors in these areas, such as pathogens, the amount of sunlight received in those parts of the world, and dietary habits of people in various cultures. The risk of MS is increased with environmental risk factors such as lack of vitamin D, cigarette smoke, and infection with Epstein-Barr virus (EBV). Some studies also suggest obesity may be a risk factor, especially for children with MS.

Genetic Factors

Scientists have performed genome-wide association studies (GWAS) in people with MS to help determine the genetic risk factors associated with MS. MS is not a hereditary disease because it is not predictably passed to family members. However, certain genes may affect a person’s susceptibility to MS when combined with other risk factors.

Much of the genetic susceptibility for MS is related to the immune system and its destruction of the myelin sheath that covers nerve cells in the central nervous system. One genetic risk factor is the human leukocyte antigen (HLA) gene HLA-DRB1*15:01. Individuals carrying this gene are three times more likely to develop MS.

Investigating Potential Clusters of MS

If someone thinks they have observed a high prevalence of MS in their community, they should report this observation to public health officials. These clusters are of interest because they may provide clues to environmental or genetic risk factors that might cause or trigger the disease.

A seemingly increased number of cases may be due to certain demographics like gender distribution and familial association, and it may be surprising how many cases of MS are predicted for a given area. Regardless, if you have concerns about the prevalence of MS in your community, public health officials may be able to determine if a cluster exists.

Talk With Others Who Understand

MyMSTeam is the social network for people with MS and their loved ones. On MyMSTeam, more than 164,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.

Are you living with MS? Share your experience in the comments below, or start a conversation by posting on your Activities page.

All updates must be accompanied by text or a picture.
Evelyn O. Berman, M.D. is a neurology and pediatric specialist and treats disorders of the brain in children. Review provided by VeriMed Healthcare Network. Learn more about her here.
Amanda Agazio, Ph.D. completed her doctorate in immunology at the University of Colorado Anschutz Medical Campus. Her studies focused on the antibody response and autoimmunity. Learn more about her here.

Related articles

Many people with multiple sclerosis (MS) have questions about whether dental work and root canals...

Do Root Canals Cause MS or Trigger Flares?

Many people with multiple sclerosis (MS) have questions about whether dental work and root canals...
Despite rumors to the contrary, scientists say that moderate artificial sweetener consumption is...

Aspartame and MS: Are Artificial Sweeteners Safe for People With Multiple Sclerosis?

Despite rumors to the contrary, scientists say that moderate artificial sweetener consumption is...
Multiple sclerosis (MS) is an autoimmune disease in which the body’s own immune system attacks...

Why Are Women More Likely To Develop Multiple Sclerosis?

Multiple sclerosis (MS) is an autoimmune disease in which the body’s own immune system attacks...
New research has found evidence that Epstein-Barr virus (EBV) infection may be a cause of...

Epstein-Barr Virus: A Link Between MS and Cancer

New research has found evidence that Epstein-Barr virus (EBV) infection may be a cause of...
Recent research shows that the Epstein-Barr virus (EBV) may be the leading cause of multiple...

Are Low Vitamin D, Smoking, and Epstein-Barr a Perfect Storm for MS?

Recent research shows that the Epstein-Barr virus (EBV) may be the leading cause of multiple...
For many years, people of European ancestry were believed to develop multiple sclerosis (MS) more...

Multiple Sclerosis and Ethnicity: Is Race a Risk Factor in MS?

For many years, people of European ancestry were believed to develop multiple sclerosis (MS) more...

Recent articles

A person can develop multiple sclerosis (MS) at any age, but the condition is most often...

What Is the Average Age for a Multiple Sclerosis Diagnosis?

A person can develop multiple sclerosis (MS) at any age, but the condition is most often...
If you're living with multiple sclerosis (MS), you may wonder how moderate or heavy alcohol consumption could affect your disease and overall well-being.

MS and Alcohol: What Are the Effects?

If you're living with multiple sclerosis (MS), you may wonder how moderate or heavy alcohol consumption could affect your disease and overall well-being.
Multiple sclerosis (MS) is a neurological condition that disrupts the signals between your brain...

Bladder Spasms and MS: Understanding the Connection

Multiple sclerosis (MS) is a neurological condition that disrupts the signals between your brain...
Muscle spasms are common among people with multiple sclerosis (MS), and they can feel worse at...

Why Are MS Muscle Spasms Worse at Night?

Muscle spasms are common among people with multiple sclerosis (MS), and they can feel worse at...
In partnership with GoodRx
If you’re sensitive to temperatures — especially heat — and your multiple sclerosis (MS) symptoms...

MS and Fever: Managing Symptoms and Body Temperature

If you’re sensitive to temperatures — especially heat — and your multiple sclerosis (MS) symptoms...
MyMSTeam My multiple sclerosis Team

Thank you for subscribing!

Become a member to get even more:

sign up for free

close