Multiple sclerosis (MS) is the most widespread disabling neurological condition of young adults around the world. You can develop MS at any age, but most people are diagnosed between the ages of 20 and 40. There are relapsing and remitting types of MS and progressive types, but the course is rarely predictable. Researchers still don’t fully understand the causes of MS or why the rate of progression is so difficult to determine. The good news is that many people with MS don’t become severely disabled and most have a normal or near-normal lifespan.
Despite much research, solid numbers on how many people have MS are hard to come by. There’s no national or global registry for new MS cases. Figures are only estimates.
The Multiple Sclerosis Foundation estimates that more than 400,000 people in the United States and about 2.5 million people around the world have MS. About 200 new cases are diagnosed each week in the United States. Rates of MS are higher farther from the equator. It’s estimated that in southern states (below the 37th parallel), the rate of MS is between 57 and 78 cases per 100,000 people. The rate is twice as high in northern states (above the 37th parallel), at about 110 to 140 cases per 100,000. The incidence of MS is also higher in colder climates. People of Northern European descent have the highest risk of developing MS, no matter where they live. The lowest risk appears to be among Native Americans, Africans, and Asians.
Interestingly enough, a child who relocates from an area of low risk to an area of high risk (or the other way around) takes on the risk level of the new location. However, the child retains the risk level of the original location if they relocate after reaching puberty.
Among the general population, MS affects more than 2.3 million people. The ratio of women with MS to men with the disease is 2 to 1.
MS is not considered an inherited disorder. But researchers believe there may be a genetic predisposition to developing the disease. For example, about 15 percent of individuals with MS have one or more family members or relatives who also have MS, according to the National Institute of Neurological Disorders and Stroke. In the case of identical twins, there’s a 1 in 3 chance for each sibling to have the disease.
Researchers still aren’t certain what causes MS. One leading hypothesis is that it’s a genetic predisposition combined with an environmental or viral factor. People with other autoimmune diseases, especially type 1 diabetes, thyroid disease, or inflammatory bowel disease, are at a slightly increased risk of developing MS. Researchers are also studying the relationship between MS and infections such as Epstein-Barr, herpes, and varicella-zoster, among others. However, MS itself is not contagious.
Frequency of Types
1. Relapsing-remitting MS (RRMS) is characterized by clearly defined relapses of increased disease activity and worsening symptoms. These are followed by remissions in which the disease doesn’t progress. Symptoms may improve or disappear during remission. Approximately 85 percent of patients are diagnosed with RRMS at onset.
2. Untreated, about 50 percent of people with RRMS transition to secondary-progressive MS (SPMS) within a decade of the initial diagnosis.
3. Primary-progressive MS (PPMS) is diagnosed in about 10 percent of MS patients at onset. People with PPMS experience a steady progression of the disease with no clear relapses or remissions. The rate of PPMS is equally divided between men and women. Symptoms usually begin between the ages of 35 and 39.
4. Progressive-relapsing MS (PRMS) is the rarest form of MS, representing about 5 percent of MS patients. People with PRMS have clear relapses combined with a steady progression of the disease.
Approximately 10 to 20 percent of people with MS have a benign course of the disease. This means they have only mild symptoms and little disease progression. However, long-term studies show that some of these people experience some progression after 10 to 20 years. About 1 percent of patients develop an aggressive form of MS that progresses very rapidly.
Symptoms and Treatment
Symptoms vary a great deal from one patient to another — no two people have the same combination of symptoms.
The most common early symptoms of MS are:
- vision problems
- tingling and numbness
- vertigo and dizziness
- muscle weakness and spasms
- problems with balance and coordination
Other, less common, symptoms include:
- speech and swallowing problems
- cognitive dysfunction
- difficulty with walking
- bladder and bowel dysfunction
- sexual dysfunction
- mood swings, depression
There is no cure for MS. Medications are designed to lessen frequency of relapses and slow the progression of the disease, but they don’t address individual symptoms.
There are currently 12 disease-modifying medications approved by the U.S. Food and Drug Administration:
- teriflunomide (Aubagio)
- interferon beta-1a (Avonex, Rebif, Plegridy)
- interferon beta-1b (Betaseron, Extavia)
- glatiramer acetate (Copaxone)
- fingolimod (Gilenya)
- mitoxantrone (Novantrone)
- dimethyl fumarate (Tecfidera)
- natalizumab (Tysabri)
- alemtuzumab (Lemtrada)
These medications are not approved for use during pregnancy. It’s also unclear if MS medications are excreted through breast milk. Talk to your doctor about your MS medications if you have MS and are considering becoming pregnant.
Other Surprising Facts About MS
Women with MS can safely carry a baby to term. Pregnancy doesn’t generally affect MS in the long-term. Women with MS often experience a relief from symptoms during pregnancy. However, about 20 to 40 percent of women have a relapse within a few months of giving birth.
MS is an expensive disease to treat. Direct and indirect health care costs range from $8,528 to $54,244 per patient per year in the United States. MS ranks second only to congestive heart failure in terms of costliness compared with other chronic conditions.
There’s no single “MS test.” Diagnosis requires a neurological examination, patient history, and a series of tests. These may include MRI, spinal fluid analysis, blood tests, and evoked potentials. Since the exact cause of MS is still unknown, there is no known prevention.