Smoking and multiple sclerosis
Fact-checked by Research over recent decades has shown a clear link between smoking and multiple sclerosis (MS), an autoimmune condition in which the immune system attacks healthy tissue in the brain and spinal cord.
Studies show smoking not only increases the risk of developing MS but also worsens the disease’s severity and progression. While the exact mechanisms are still being studied, inflammation caused by tobacco smoke is believed to play a key role.
Smoking and the risk of MS
MS cases are believed to arise from a combination of genetic and environmental risk factors, and smoking is a well-established contributor. People who currently smoke or previously smoked are about 50% more likely to develop MS than those who have never smoked.
This relationship is dose-dependent, meaning the risk of developing MS increases with both the number of cigarettes smoked per day and the total years spent smoking. There’s also a link between exposure to secondhand smoke and MS risk, including in children who were exposed to tobacco smoke at home.
The exact mechanism behind this association is not fully understood, but research suggests it isn’t nicotine, the addictive substance in cigarettes, that drives the increased MS risk. Instead, research indicates that smoking releases toxic molecules that irritate the lungs and create an inflammatory environment in the body.
Smoking is believed to weaken the blood-brain barrier, a selective membrane that controls which substances in the bloodstream can enter the brain. When this barrier becomes compromised, overactive immune cells may more easily reach the brain and spinal cord and contribute to MS-related nerve damage.
Vaping and MS risk
Many people have turned to electronic cigarettes, or vaping, as an alternative to smoked tobacco.
Research directly examining the effects of vaping on MS is still limited. However, because vaping also involves inhaling substances into the lungs, it may trigger inflammation and disrupt the blood-brain barrier in ways similar to traditional smoking. This means vaping could carry comparable risks for people with MS.
Chewing tobacco has not been shown to increase MS risk, likely because it is not inhaled into the lungs. This suggests that for people struggling to quit smoking, non-inhaled nicotine products, such as patches, gum, or lozenges, may be better options than vapes or low-nicotine smoking alternatives, since they do not expose the lungs to inflammatory particles.
Smoking and MS outcomes
After an MS diagnosis, continued smoking can negatively impact many MS outcomes. It is linked with greater disease activity, faster disease progression, higher disability, and more severe symptoms.
Greater disease activity and faster progression
Research shows that smoking can make MS more active and cause it to progress more quickly.
- Disease activity: People with MS who smoke tend to have more brain lesions and brain atrophy on MRI scans, as well as more frequent or severe relapses than nonsmokers.
- Transition from RRMS to SPMS: Among people with relapsing-remitting MS (RRMS), smoking is associated with a higher risk of converting to secondary progressive MS (SPMS). A landmark study found people who continued to smoke after their RRMS diagnosis transitioned to SPMS an average of eight years earlier than people who quit after diagnosis.
- CIS to MS transition: People with clinically isolated syndrome (CIS) are also more likely to be diagnosed with clinically definite MS if they are smokers.
- Disability progression: Smoking is linked to faster accumulation of disability in MS. Studies show that people who smoke reach key disability milestones sooner than nonsmokers or those who quit after diagnosis.
Reduced therapeutic efficacy
Smoking may reduce the effectiveness of disease-modifying therapies (DMTs) for MS, further impacting the disease course.
For example, smoking has been shown to promote the development of neutralizing antibodies that reduce the benefits of certain medications, such as interferon-based therapies.
Data also suggest smokers on some DMTs are more likely to experience relapses than nonsmokers on the same medication.
Worse symptoms and quality of life
Beyond long-term outcomes, smoking can also worsen a range of MS symptoms, making day-to-day life more difficult. Some of these symptoms include:
- cognitive decline
- mobility issues
- fatigue
- depression and other mood problems
- pain and abnormal sensations
- vision problems.
Smokers also face higher risks of other health conditions, such as lung cancer, heart disease, and respiratory diseases. These additional health issues can further impact overall well-being and quality of life for people with MS.
Benefits of quitting smoking after MS diagnosis
While quitting smoking cannot reverse the nerve damage that has already occurred, there are numerous benefits to smoking cessation at any time after an MS diagnosis.
Stopping smoking can:
- slow the rate of disability progression
- reduce the risk of transitioning from RRMS to SPMS
- improve the efficacy of DMTs
- improve mood, cognition, and energy levels, making daily life easier
- lower the risk of other health conditions.
It is important to remember that it is never too late to quit. Stopping smoking at any stage can help mitigate the negative effects of smoking on people with MS and support better long-term outcomes.
People who want to quit should speak with their healthcare providers about effective cessation aids, counseling, or other support services that can make the process easier.
Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
