Multiple sclerosis (MS) is pretty quirky as far as diseases go. Some of the nuances surrounding who gets it and when continue to baffle experts.
Here's what they know for sure: MS is an autoimmune disease that occurs when the body misfires against its own central nervous system.
What sets off the process is unknown, but is thought to be a combo of genes plus environment. Here are 12 things linked to a higher risk of MS.
Montel Williams and a few other high profile male celebs have been diagnosed with MS, but by and large, MS disproportionately strikes women, says Nancy L. Sicotte, M.D., the director of the Multiple Sclerosis Program at Cedars-Sinai Medical Center in Los Angeles. The gender gap is growing.
"It used to be two women to every one man, but several new studies suggest it is approaching 4:1," she says.
Even though women are more likely to develop MS, the disease tends to be more severe in men, adds Dr. John Rose, a professor of neurology at the University of Utah in Salt Lake City.
|Where You Live|
People who live closer to the earth's poles (Think: Australia, New Zealand, parts of North America, Canada, and Iceland) are at higher risk for MS than those who live closer to the equator. This is true in the U.S. too.
MS is twice as prevalent in North Dakota than Florida, for example. "We have always been puzzled by this," says Dr. Rose. The likely culprit is vitamin D or lack thereof. Our bodies make vitamin D in response to sunlight, so people far from the equator make less, especially during the long, dark winter months.
|Your Vitamin D Levels|
Vitamin D deficiency has been linked to a host of illnesses—including MS.
But before you go thinking you have a handle on it, there are MS hot spots in locations that do get lots of sunlight including parts of Greece and Italy.
"We think migration patterns and environmental aspects may have something to do with this," says Dr. Rose.
|When You Were Born|
This is strange, but true. "If your mother was pregnant with you through the winter, you are at greater risk for MS," Dr. Rose says. "It's a curious phenomenon, but if you are born in spring or late spring, your mom's levels of vitamin D during pregnancy may have been low which could explain it."
Finnish researchers found that spring babies are at higher risk of MS. According to this study, an April birth was linked to a 9.4% higher MS risk, while those born in November had an 11.1% lower risk.
MS is more common in whites, particularly those with Northern European ancestry. Some groups—people with African, Asian, Hispanic, and Native American ancestry—seem to be at lower risk, although they can still get the disease.
MS is almost unheard of among some groups according to the National Multiple Sclerosis Society, including the Inuit, Australian Aborigines, and New Zealand Maoris.
|You Moved as a Child|
If you move as a child, your risk of MS will change to match your new homeland, whether you move from a low risk to high risk area for MS or vice versa. However, this is true only if you moved before roughly the ages of 12 to 15; after puberty, such a move doesn't seem to matter.
"If your parents came to the U.S. from the Orient, they seem protected, as do their children," Dr. Rose says. "The second generation—i.e. their grandchildren—may be at a higher risk for developing MS." This suggests that environmental factors may play a role, he says.
|Your Smoking Status|
We all know that smoking is bad news, and that it increases the risk of lung cancer and heart attack. But few know that it's a well established risk factor for MS too.
Smokers and ex-smokers are more likely to be diagnosed with MS than people who never smoked and the more cigarettes you smoke the higher the risk (5-fold greater risk at more than 4 packs a day).
While you can't go back and unsmoke cigarettes from the past (we wish), it can help to quit if you're still puffing away. Research suggests that MS may progress more quickly in current smokers.
MS can be diagnosed at almost any age, from childhood right on up to your years as a senior citizen. However, it's more likely to occur in people ages 20 to 50.
"MS is not an all comers disease, " says Carrie Lyn Sammarco, a nurse practitioner at the Multiple Sclerosis Comprehensive Care Center of New York University Langone Medical Center. "We don't tend to see it in children, although it can occur," she says.
|You've Had Mono|
Many germs have been studied as possible MS triggers, but the results have been mixed. There is, however, a growing body of evidence for Epstein-Barr virus (EBV), which causes mononucleosis. (Mono symptoms are fever, sore throat, and swollen glands.)
A Journal of the American Medial Association study found higher levels of EBV antibodies in people with MS. (About 95 percent of people are infected with EBV at some point, but not all get symptoms.) Wayne State University researchers found that a history of EBV is more common in people with MS. While no cause and effect has been established, "a relationship is clearly present," they concluded.
|You Have Another Autoimmune Condition|
Autoimmune diseases tend to cluster. This means that if you have one, you may also develop others.
So that means if you have type 1 diabetes or inflammatory bowel disease, you may have a slightly higher risk of being diagnosed with MS too. However, the link isn't as strong with other autoimmune diseases, such as lupus and rheumatoid arthritis, says Dr. Rose.
"Genes seem to set up the haywire autoimmune system," he says.
|Your Family Tree|
While the environment has an impact on MS risk, so too, does genetics. "If a mom has MS, her children have a 5 percent risk of having MS, and if a dad does, his daughters also have a 5% risk, but his sons have less of a risk," says Dr. Rose.
It's usually a combo of factors—genes and environmental triggers—that result in MS, even within families.
For example, the MS risk is 1 in 750 for most people, 1 in 40 for those with close family members with the disease, and 1 in 4 for those with an identical twin with it.
|You've Experienced Extreme Grief|
Stress can worsen MS symptoms and some research suggests that it can even increase the risk of developing MS in the first place.
One study found that parents of children who died were more likely than other parents to develop MS in the next decade, and the risk seemed even higher—twice as likely—if the death was unexpected (such as an accident).
"We are still trying to figure out how much and what type of stress could lead to flare ups, worsening disease or even cause MS," Dr. Rose says.