How Smoking Affects Multiple Sclerosis Progression
It likely comes as no surprise that smoking is not good for people who have multiple sclerosis, but what may be news is how smoking impacts disease progression. A new study from Karolinska Institutet explains the effects of smoking on MS and is believed to be the first one to provide evidence of what happens when MS patients quit smoking, while another recent study also reveals news about smoking and MS prognosis.
Multiple sclerosis and smoking
In an article from May 2015, a team of investigators explored the impact of the environment on multiple sclerosis. They noted that “Epstein-Barr virus infection, smoking, and low vitamin D levels are the environmental factors that have shown the strongest and most consistent association with development of the disease.”
But what about people with multiple sclerosis who continue to smoke after they are diagnosed? In an article published online September 8, 2015 by JAMA Neurology, Jan Hillert, MD, PhD, and colleagues at Karolinska Institutet in Stockholm compared disease progression among patients who continued to smoke with those who had quit.
The participants included 728 individuals with MS who smoked at diagnosis and a control group of 1,012 patients who had never smoked. Of the 728 patients
- 332 continued to smoke from the year after they were diagnosed
- 118 quit smoking during the year after diagnosis
- 278 were classified as intermittent smokers
- 216 patients converted from relapsing-remitting MS to secondary progressive MS
Individuals with MS typically convert to secondary progressive MS after about 20 years from onset of the disease. The length of time from onset to this conversion is often used as a way to measure disease progression.
Based on an analysis of the study participants, the authors suggested that
- The time to conversion to secondary progressive MS was accelerated by 4.7 percent for each additional year a patient smoked after diagnosis
- Individuals who continued to smoke each year after they were diagnosed converted to secondary progressive MS faster (at age 48) than those who had quit smoking (at age 56)
Overall, the investigators concluded that continuing to smoke after getting a diagnosis of multiple sclerosis has a negative effect on disease progression, and that reducing or stopping smoking may improve quality of life and delay progression to secondary progressive MS.
Smoking and multiple sclerosis: another study
An April 2015 article in the Journal of Neuroimmunology explored how smoking worsens multiple sclerosis prognosis. The authors uncovered evidence of:
- Activity of a specific enzyme is reduced in individuals with multiple sclerosis who smoke. This leads to increased production of two cytokines involved with inflammation and/or immune response: interleukin-6 (IL-6) and interleukin-13 (IL-13)
- Changes occur in the renin-angiotensin system of MS patients who smoke, which results in an increase in two more interleukins (IL-17, IL-22) as well as greater production of substances called chemokines, which are also involved with inflammation
- A significant decline in the number of regulatory T cells, which are critical for maintaining immune cell balance
The authors concluded that smoking worsens the prognosis of multiple sclerosis and that these specific activities contribute to that decline.
It’s clear from these studies that smoking is detrimental to the prognosis and well-being of individuals who have multiple sclerosis. Any individual with multiple sclerosis who still smokes should seek help to quit.
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Correale J, Farez MF. Smoking worsens multiple sclerosis prognosis: two different pathways are involved. Journal of Neuroimmunology 2015 Apr 15; 281:23-34
Loken-Amsrud KI et al. Impact of the environment on multiple sclerosis. Tidsskr Nor Laegeforen 2015 May 19; 135(9): 856-60
Ramanujam R et al. Effects of smoking cessation on multiple sclerosis prognosis. JAMA Neurology 2015 Sept 8 online. doi:10.1001/jamaneurol.2015.1788