Multiple Sclerosis Society of Canada

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Researchers link continued smoking to accelerated MS progression

Background

There is mounting evidence to suggest that smoking tobacco not only increases a person’s risk of developing multiple sclerosis (MS), but can also accelerate the disorder’s progression. While a number of studies have examined the link between smoking and MS, certain aspects of the relationship remain unexplored; for example, the potential benefit of quitting once diagnosed with MS. 

Over the last few years, Dr. Jan Hillert, a researcher at the Karolinska University Hospital Solna, Sweden, has led a team of scientists to address this very question – how does quitting chronic smoking affect the course of an individual’s MS once they are diagnosed? In particular, Dr. Hillert’s team wanted to understand whether smoking can alter the time it takes for relapsing remitting MS to convert to secondary progressive MS. The findings were recently published online in the journal JAMA Neurology.

The Study

Data was collected between 2009 and 2011 using detailed questionnaires sent out to participants listed in the Swedish National MS Registry as part of the Genes and Environment in Multiple Sclerosis Study. The study focused on those who were active smokers when they received their MS diagnosis.  This included 332 individuals who continued to smoke after diagnosis, and 118 individuals who subsequently quit. The researchers defined smoking as having “averaged at least one cigarette per day” over the course of a year.

Using the questionnaire data, the researchers assessed whether continued smoking after MS diagnosis affected the conversion time from relapsing remitting MS to secondary progressive MS, compared to those individuals who quit smoking.

Results

For each additional year a person smoked after receiving their diagnosis, the conversion time from relapsing remitting to secondary progressive MS accelerated by 4.7%. Those who continued to smoke, on average, developed secondary progressive MS eight years sooner than those who quit upon being diagnosed.

Comment

These findings provide compelling evidence from an observational study that continued smoking negatively affects MS prognosis, accelerating the relapsing-remitting form of the disorder towards a progressive form.  The effect was cumulative; each successive year of smoking accelerated the conversion time by an additional 4.7%.  Overall, those who continued to smoke, on average, developed secondary progressive MS eight years sooner than those who had quit.

This study adds to the substantial body of evidence that smoking is associated with numerous adverse health conditions, and provides additional rationale for those living with MS to avoid or quit smoking to prevent worsening their risk of disease progression. Further questions that need to be answered in future studies include: how does occasional smoking affect the prognosis of individuals living with MS, and can quitting smoking provide benefits to symptom management and disease progression at any stage of the disease course, not just upon diagnosis?

Source

Ramanujam R et al. (2015). Effect of smoking cessation on multiple sclerosis prognosis. JAMA Neurology. DOI: 10.1001/jamaneurol.2015.1788.