No one today would argue that smoking is good for you. But for people with MS and their families, smoking can bring added risks.
We explain why smoking and multiple sclerosis are a toxic combination when it comes to managing your symptoms and preserving your health. In terms of your MS, it is never too late to quit.
MS is likely caused by having a genetic vulnerability and one or more environmental risk factors, such as a viral infection, lack of vitamin D, or smoking.
The relationship between MS and smoking has been recognised for many years, with recent studies showing:
They also show that If you have MS and smoke:
If you have a genetic vulnerability to MS, then smoking makes the risk worse. For example, a study showed that 20% of all MS cases in Sweden are associated with smoking or passive smoking. However, this rises to 41% among those with a genetic susceptibility to MS.
So, if you or a family member has MS or you have a genetic vulnerability to MS, smoking and passive smoking are particularly risky for you and your children.
The exact processes are not fully understood, but these theories offer potential explanations:
One possibility is that exposure to cigarette smoke damages the cells that line the lungs. This causes chemical changes to the DNA in these cells and upsets the balance of proteins produced by the healthy cells. It is possible that this imbalance makes the blood-brain barrier weaker.
Immune cells attracted to the damaged lung cells pass into the central nervous system and begin to attack the nerves. The more you smoke, the worse the effect.
With this theory, it is not the nicotine in cigarettes that is the problem, but the irritation to the lungs. Similar effects are seen in exposure to other lung irritants produced by air pollution and smoke machines.
An alternative theory is that smoking reduces the amount of oxygen getting to the brain and other tissues. This is called hypoxia. The stress, caused by the lower oxygen levels, damages the glial cells. These are support cells in the central nervous system. This in turn weakens the blood-brain barrier.
Smoking affects the disease course in several ways - none of them positive. A recent study of people with MS showed smokers reported a lower quality of life, more MS activity and greater disability.
If you smoke, you are more at risk of developing other autoimmune diseases, vascular diseases, type 1 diabetes or having a stroke. This is like anyone else in the population.
But having MS as well as another serious illness makes managing both diseases harder. In any given year, smokers with MS are twice as likely to die as non-smokers with MS. Much of this extra risk comes from the way symptoms of one disease make the other worse.
Smoking makes pain worse in MS. This includes neuropathic pain, back pain, headaches and painful spasms. Pain is a significant symptom for many people with MS and can increase your risk of depression and fatigue. Smokers are also more likely to report extreme pain than non-smokers with multiple sclerosis.
Pain, depression and smoking can form a vicious cycle. It's hard to stop smoking if you think it is helping to manage your pain. If this is a problem for you, do seek help with pain management from your doctor or MS nurse.
Both smoking and MS are associated with reduced bone mineral density leading to weaker bones. This combination puts you at increased risk of fractures.
Smoking affects the brain and is associated with cognitive decline, reduced brain volume and dementia in the general population. Our brains may naturally shrink as we age, and smoking accelerates this process. This reduces the cognitive reserve, or buffer zone, which allows our brains to remain flexible and deal with damage such as that caused by MS.
When people with clinically isolated syndrome were scanned, smokers were found to have more lesions in their brain white matter and more abnormalities than non-smokers. Another study found that smokers with MS had reduced gray matter in the brain than non-smokers. Gray matter in the brain is made up of the nerve cell bodies, whereas white matter consists mostly of the axons and their support cells. A further study showed that heavy smokers with MS have increased cognitive impairment compared to non-smokers with MS.
Among those diagnosed with a first case of clinically isolated syndrome (CIS), 67% of smokers go on to develop MS, compared to 35% of non-smokers. The best advice is to quit smoking at the time of a CIS diagnosis.
Recent studies show that smoking increases the relapse rate in people with relapsing remitting MS (RRMS), and also increases the risk of disease progression. This means that you are more likely to need a mobility aid or wheelchair earlier than non smokers for example.
Smoking also increases the speed and risk of progression to secondary progressive MS (SPMS). This means that for smokers an SPMS diagnosis comes about four years earlier than non-smokers. After an RRMS diagnosis, every additional year spent smoking speeds up this progression risk by 4.7%.
However, smoking has not been shown to affect the age of onset in primary progressive MS, nor influence its disability progression. There may be different underlying disease processes going on.
There is some good news.
By stopping smoking, you can reduce many of the risks listed above. Every smoke-free year decreases your risk of worsening disability, and ex-smokers have the same risk of MS progression as non-smokers.
After you stop smoking, the changes to your lung lining cells steadily repairs. After five years, your lung cells look the same as a person who never smoked. Cutting down on the amount you smoke also helps reduce the damage.
It is never too late to stop smoking.
In recent years, personal devices to deliver a nicotine vapour have become widespread. However, the vaping industry is not standardised. The chemical composition of the products, the doses and vaping technology is highly variable. Vaping is often described as being 'healthier' than cigarette smoking, but for people with MS this claim is not supported.
What little research has been done suggests that vaping could be just as bad for the blood-brain barrier as smoking. It is therefore bad for MS risk as well. Although the substances in vape liquids may be food grade, they have rarely been tested for inhalation. These substances may be just as irritating to the lung lining cells, and the process of vaping still causes localised hypoxia and oxidative stress.
It appears that the nicotine itself is not the problem for the blood-brain barrier or MS, but how it gets into your body. For example, chewing tobacco has not been shown to increase MS risk. If you are trying to quit smoking consider using nicotine patches or lozenges rather than vaping, low nicotine or nicotine free tobaccos. This also applies to smoked cannabis.
Taking a disease modifying drug (DMD) doesn’t protect you from the impact of smoking on your MS.
A study of 834 Danish people with relapsing remitting MS on beta interferon treatment found 27% more relapses among smokers than non-smokers, irrespective of their underlying genetic susceptibility.
This implies that smoking makes your disease modifying treatment less effective at protecting you from relapses.
