|
Cigarettes, not snuff,
increase multiple sclerosis risk
Reported September 10, 2009
EU-funded researchers in Sweden have discovered that while tobacco smoking
raises the risk of multiple sclerosis (MS), snuff does not. The findings are
published in the journal Neurology.
The research is part of the NEUROPROMISE ('Neuroprotective strategies for
multiple sclerosis') project, supported under the 'Life sciences, genomics
and biotechnology for health' Thematic area of the EU's Sixth Framework
Programme (FP6).
Scheduled to end in 2010, NEUROPROMISE seeks to identify the major genes and
critical pathways associated with MS and inflammatory neurodegeneration, as
well as to elucidate the key immunopathological mechanisms of
neurodegeneration. The project also aims to develop novel neuroprotective
drugs based on targets validated in animal models.
MS is a chronic neurological disease affecting about 1.2% to 1.6% of Swedes.
Data also show that more women suffer from MS than men. While researchers
have found a genetic component in the disease, environmental factors such as
smoking also play a role in increasing the risk of MS.
While eight out of nine studies investigating smoking and MS risk have shown
that smokers have a greater chance of developing MS, only one study assessed
'cumulative dose' or the length of time people smoked, and MS risk.
The Swedish study, led by Dr Anna K. Hedström of the Karolinska Institutet,
investigated whether the use of Swedish snuff affects a person's chances of
developing MS. According to Dr Hedström, Swedish snuff is different from US
snuff in that it is a moist powder and usually does not involve any spitting
by the user.
'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,' Dr Hedström explained. 'These results could mean that nicotine
is not the substance responsible for the increased risk of MS among
smokers.'
Users place the snuff under the upper lip and absorb large amounts of
nicotine in the process, according to the researchers.
The team used a 2,757-strong sample comprising 902 people diagnosed with MS
and 1,855 people without MS. The ages of the Swedish subjects ranged from 16
to 70. Each participant completed a questionnaire about tobacco cigarettes
and snuff use.
The researchers found that for men, smokers had a 1.8-times-higher chance of
having MS than non-smokers, and for women, smokers were 1.4 times more
likely to have MS than non-smokers. Even moderate smokers of both sexes are
at greater risk, the data showed.
Also, even if a person were to stop smoking, the risk for being diagnosed
with MS remains high for up to five years, according to the study. But the
researchers also discovered that taking Swedish snuff for more than 15 years
decreased the risk of developing MS. It should be noted that no significant
effect was found for snuff use of less than 15 years.
'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,' Dr Hedström pointed out.
'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.' |
