Multiple sclerosis - Risk factors for multiple sclerosis

Multiple sclerosis

Risk factors for multiple sclerosis

Doctors call things that make you more likely to get a disease risk factors. Having a risk factor for multiple sclerosis (MS) doesn't mean you'll get the disease. It just means you're more likely to get it than someone who doesn't have the risk factor. These are the main risk factors for MS.

Your family and your genes

You're more likely to get MS if other people in your family have it, especially a brother or sister.

Source:
Hauser SL, Goodkin DE.
Multiple sclerosis and other demyelinating diseases.
In: Braunwald E, Fauci AS, Kasper DL, et al (editors). Harrison's principles of internal medicine. 15th edition. McGraw Hill, New York, USA; 2001.

¹ If you have a close relative with MS, you have about a 2 in 100 to 3 in 100 chance of getting it yourself.

There isn't any single

genes
Your genes are the parts of your cells that contain instructions for how your body works. Genes are housed on chromosomes, structures that sit in the nucleus at the middle of each of your cells. You have 23 pairs of chromosomes in your normal cells, each of which has thousands of genes. You get one set of chromosomes, and all of the genes that are on them, from each of your parents.

gene that causes MS. Instead, some people probably get a mix of genes from their parents that increases their risk.

¹ This means you may be more likely to get MS if you have these genes. But other things also need to happen for you to get it.

Infections

Infections probably don't cause MS on their own. But they might trigger the disease if you have genes that make you more likely to get MS.

Source:
Keegan BM, Noseworthy JH.
Multiple sclerosis.
Annual Review of Medicine. 2002; 53: 285-302.

Here are some of the infections that might be related to MS, especially if you get one of these as a teenager:

measles
Measles is a disease caused by a virus. It's common for children to get measles. It causes you to break out in a rash all over your body. It also gives you swollen glands and flu symptoms, like tiredness and fever. Sometimes it can cause worse problems, like an infection in the lungs or voice box. The measles-mumps-rubella (MMR) vaccine protects children from getting measles.

Measles
herpes simplex
Herpes simplex is a virus that causes a blistering skin rash. There are two different types of herpes simplex virus (HSV). HSV1 causes cold sores in your mouth. It's usually spread through saliva or through direct skin contact (like kissing). HSV2 causes a rash in your genital area. It is spread by rubbing during intimate contact (like having sex or sexual foreplay).

Herpes
chickenpox
Chickenpox is a common childhood illness caused by a virus. It usually leads to a fever, tiredness and an itchy rash. The virus can easily spread from person to person, and people usually get it about two weeks after they were around someone with the illness. About two days before the rash starts, you can give the virus to others. Chickenpox clears up on its own in most children, but adults and some children may get complications such as pneumonia, kidney problems or heart problems. You can get a chickenpox vaccine to help protect you from this infection.

Chickenpox
rubella
Rubella is a childhood infection caused by a virus. It usually starts with mild cold symptoms, a sore throat and swollen glands. After that, you get a pink rash that spreads from your head to the rest of your body. Some people call it German Measles. The measles, mumps and rubella (MMR) vaccine protects children from getting rubella.

Rubella
Mononucleosis or "mono" (an infection with the

Epstein-Barr virus
Epstein-Barr virus (or EBV for short) is a common cause of infections in children and adolescents. It's the virus that causes mononucleosis or "mono." This infection can give you a sore throat, fever and swollen glands in your neck. If you've had an EBV infection, you may be more likely to get other conditions later in life, such as certain types of lymphoma (including Hodgkin's disease) and multiple sclerosis.

Epstein-Barr virus)
Some types of flu
chlamydia
Chlamydia is an infection you can get by having sex without a condom. It can cause pain or discomfort and discharge from your sexual organs. If you're a woman, it can also cause infertility or a painful infection inside your body.

Chlamydia.

These infections can stir up your

immune system
The immune system is made up of the parts of the body that are devoted to fighting infection. The body is constantly being threatened by infections from things like bacteria, viruses and parasites. The immune system fights these infections in different ways. At the microscopic level, the immune system uses antibodies and white blood cells, which travel in the blood and target infectious agents, such as bacteria. These microscopic parts of the immune system either kill the infectious agent directly, or take it to other parts of the body, like the spleen, where it can be dealt with. The lymph nodes are another important part of the immune system. Within them, white blood cells filter through the foreign material that has entered the blood, to see if there are any infections. When you have a swollen gland during a cold, this is actually a lymph node that is reacting to the infection. Unfortunately, it is possible for the immune system to become confused and to use its destructive powers to target healthy parts of the body. Diseases that result from this type of situation are called autoimmune diseases.

immune system, which may go on to attack your nerves by mistake.

Source:
Keegan BM, Noseworthy JH.
Multiple sclerosis.
Annual Review of Medicine. 2002; 53: 285-302.

Where you live

MS is more common in colder countries that are farther from the equator (the imaginary line that wraps around the middle of the earth).

In the United States, MS is more common in northern than southern states.

Source:
Hernan MA, Olek MJ, Ascherio A.
Geographic variation of MS incidence in two prospective studies of US women.
Neurology. 1999; 53: 1711-1718.

³
Below the equator, MS is more common in the southern part of Australia than farther north.

Source:
Noseworthy JH, Lucchinetti C, Rodriguez M, et al.
Multiple sclerosis.
New England Journal of Medicine. 2000: 343: 938-952.

⁴

No one knows why this is. But your chance of getting MS seems to depend on where you lived as a child. So if you move from a colder country or state to a warmer one after the age of about 15, it doesn't lower your risk of getting MS.

Sources for the information on this page:

Hauser SL, Goodkin DE.Multiple sclerosis and other demyelinating diseases.In: Braunwald E, Fauci AS, Kasper DL, et al (editors). Harrison's principles of internal medicine. 15th edition. McGraw Hill, New York, USA; 2001.

Keegan BM, Noseworthy JH.Multiple sclerosis.Annual Review of Medicine. 2002; 53: 285-302.

Hernan MA, Olek MJ, Ascherio A.Geographic variation of MS incidence in two prospective studies of US women.Neurology. 1999; 53: 1711-1718.

Noseworthy JH, Lucchinetti C, Rodriguez M, et al.Multiple sclerosis.New England Journal of Medicine. 2000: 343: 938-952.

This information was last updated on Jul 25, 2008

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