Smoking & Multiple Sclerosis (MS)

Smoking and the Risk of Developing MS

Smoking is widely known to be harmful, but for people diagnosed with multiple sclerosis (MS), we now have evidence of a very specific detrimental effect for not only the user, but also the extending risks involved for family members.

Several large-scale studies have confirmed a clear link between smoking and an increased risk of developing MS.

For example, the Nurses’ Health Study revealed that women who smoked were significantly more likely to be diagnosed with MS. Compared to those who never smoked, current smokers had a 60% higher risk, while former smokers still carried a 20% increased risk.

A Norwegian study also demonstrated how the risk of developing MS was highest among individuals who had smoked for more than 25 years.

It showed that smokers were nearly twice as likely to develop MS as non-smokers. For individuals with Clinically Isolated Syndrome (CIS) – a condition that sometimes precedes MS – smoking nearly doubled the likelihood of progressing to a confirmed MS diagnosis, and doing so at an earlier age.

How Smoking Affects MS Progression

For those already diagnosed with MS, smoking can accelerate disease progression. The risks for people with MS who smoke include:

• Increased risk of disease progression
• Earlier onset of SPMS
• Greater levels of disability
• Lower quality of life
• Increased likelihood of other autoimmune diseases

Researchers at Harvard School of Public Health conducted a well-designed case-control study on smokers with MS. People with MS who had ever smoked were three to four times more likely to develop secondary progressive MS than those who had never smoked.

Another study followed 122 people with MS over six years and found that smokers were not only more likely to experience progression, but to do so at a younger age.

Additionally, smoking after diagnosis has been associated with a 23% higher chance of developing another autoimmune condition — a particularly concerning risk for those already managing MS.

Finally, one of the most compelling studies came from the Karolinska Institute in Sweden. It followed 728 people with MS who smoked at the time of diagnosis. Those who continued smoking transitioned to SPMS about eight years earlier than those who quit. Moreover, every additional year of smoking after diagnosis shortened the time to progression by approximately 5%.

As Professor George Ebers has pointed out, the transition to SPMS is often a more meaningful indicator of long-term MS activity than the frequency of relapses.

Does smoking put family members at risk?

Research has shown that children exposed to second-hand smoke are more than twice as likely to develop MS if a parent smokes. The longer the exposure, the higher the risk. One study estimated that passive smoking increases a child’s risk of developing MS by around 30%.

Given that relatives of people with MS already have a higher genetic likelihood of developing the disease, exposure to cigarette smoke only compounds the risk.

It’s also worth being aware of the other environmental factors that can increase the risk of developing MS to take the best care of your family.

Insights from the HOLISM Study

The Health Outcomes and Lifestyle In a Sample of people with MS (HOLISM) study, led by Professor George Jelinek, offers valuable insight into the relationship between smoking and MS outcomes.

The study found that smoking status, the amount smoked, and the time since quitting were all significantly associated with disability levels:

• Never-smokers were more likely to have minimal disability
• Current smokers had greater disability, and this increased with the number of cigarettes smoked daily
• Those who had quit over 10 years ago still had higher odds of major disability than never-smokers
• Current smokers were nearly twice as likely to have major disability

In terms of quality of life, the pattern was clear: people who had never smoked reported significantly better wellbeing across physical and mental health domains compared to both current and former smokers.

In conclusion, smoking not only increases the risk of developing MS, but also worsens outcomes for those already living with the condition. It accelerates disease progression, increases disability, reduces quality of life, and puts family members at greater risk through second-hand smoke.

Quitting smoking is one of the most powerful actions someone with MS, or at risk of MS, can take to protect both you, and your family members’ health.