Many studies have shown that smoking is a risk factor for developing multiple sclerosis, or MS. Now, researchers at the Johns Hopkins University School of Medicine in Baltimore have released new data showing that starting the smoking habit early can significantly increase the risk of MS and its progression in adult life.
The study involved 87 people with MS among 30,000 adults interviewed in the 2002 National Health Interview Survey of American Households. The people with MS were divided into three groups-- non-smokers, early smokers younger than age 17, and late smokers older than 17 - and matched with 435 people without the disease.
According to lead author Joseph Finkelstein, assistant professor of medicine at Johns Hopkins, the study considered age, gender, race, medical status, income and geographic location.
"Still, after accounting for all these factors," he says, "early smoking accounted in a three-fold increase in the risk of developing multiple sclerosis."
More than 32 percent of the MS patients were early smokers, compared with 19 percent of the people without MS. Finkelstein says smoking does not cause MS, but puts a person predisposed to the disease at greater risk.
"Multiple sclerosis has a strong genetic component, but it is believed that people who have a predisposition to developing multiple sclerosis may not develop multiple sclerosis if they are not subjected to certain triggers. What our study shows is that for multiple sclerosis, early smoking is a very strong trigger."
Finkelstein says that may be because smoking suppresses the immune system of people already genetically susceptible to the disease.
The study was done in collaboration with the U.S. Veterans Affairs Administration's Multiple Sclerosis Center for Excellence, which services the health care needs of the 28,000 veterans with the disease.
Finkelstein says the findings give young people another reason not to smoke cigarettes. He will present the study at the annual meeting of the American Academy of Neurology in late April.