The role of different genetic and environmental factors in influencing a person’s susceptibility to multiple sclerosis (MS) has always been a matter of debate in medical science. Among various environmental risk factors, cigarette smoking has emerged as an important risk factor that may not only increase the risk of developing MS but also may influence disease progression in MS patients.
Smoking and the risk of MS
Over the years, studies have identified a link between cigarette smoking and the risk of developing MS. It has been found that the risk of MS in smokers is 1.5 times higher compared to nonsmokers.
Several epidemiological studies conducted in the past have found significant links between smoking habits and MS. These studies indicate that a dose-response effect may also exist, and people who smoke more may be at a greater risk of developing MS.
Additionally, a link between smoking and other environmental and genetic risk factors has also been established. Smoking is found to interact with factors such as Epstein-Barr virus (EBV) and levels of vitamin D (or exposure to ultraviolet rays). For example, a cross-sectional study from Denmark of 517 healthy people found that smoking and the cumulative effects of tobacco were positively associated with EBV antibody levels – antibodies that are said to be critically involved in causing MS.
Smoking and MS progression
Researchers have also found an association between smoking and MS progression. In early stages of MS, most patients have relapsing-remitting MS (RRMS), the most common form of MS, where symptoms appear at random or come and go. These infrequent symptoms may last for several years. As the disease progresses, patients may develop secondary progressive MS (SPMS), when symptoms occur more frequently and there is a steady deterioration of the brain as well as the spinal cord.
In a study, researchers assessed the association between cigarette smoking and progression of MS from RRMS to SPMS. They studied 179 patients diagnosed with RRMS and their smoking habits and found that the risk of progressing to SPMS was 3.6 times higher for current and past smokers compared to people who never smoked. The study also concluded that cigarette smoking may transform or hasten the transformation of MS into progressive forms.
There is enough scientific evidence suggesting that smoking may not only increase the risk of developing MS but may also influence disease progression. Considering this, it would be crucial for people diagnosed with MS to give up cigarette smoking.