Cigarettes and not Swedish snuff increase the risk of developing multiple sclerosis

While smoking cigarettes appears to significantly increase a person's risk of developing multiple sclerosis, using Swedish snuff does not, according to a study published in the September 1, 2009, print issue of Neurology®, the medical journal of the American Academy of Neurology.

"While tobacco cigarettes increased a person's risk of developing MS, our research found that using Swedish snuff was not associated with an elevated risk for MS," said study author Anna Hedström, MD, of the Swedish medical university Karolinska Institutet in Stockholm."These results could mean that nicotine is not the substance responsible for the increased risk of MS among smokers."

The study involved 902 people diagnosed with MS and 1,855 people without MS in Sweden between the ages of 16 and 70. All participants answered a questionnaire about tobacco cigarettes and snuff use.

The researchers found that in women who smoked, the risk for developing MS was nearly one and a half times higher than in women who did not smoke. In men, the risk was nearly two times higher in those who smoked compared to those who did not smoke. This was the case even in people who only smoked moderately.

The risk remained high for up to five years after the participant stopped smoking and the risk climbed the more a person smoked. However, the study also found that people who used Swedish snuff for more than 15 years were 70 percent less likely to develop MS than those who had never used any type of tobacco. However, there was no significant effect of snuff-taking for less than 15 years, a period during which other adverse consequences of taking snuff, including head-and-neck cancer, would become evident.

Swedish snuff differs from snuff commonly used in the United States in that it is typically a moist powder that usually does not result in a need for spitting.

"Taking snuff, however, may have other harmful effects, and our findings should not be interpreted to mean that Swedish snuff is recommended to prevent disease," said Hedstrom. "More research is needed to better understand the mechanisms behind the findings. Theories are that smoking may raise the risk of MS by increasing the frequency and persistence of respiratory infections, or by causing autoimmune reactions in genetically susceptible people."