ClinicSpeak: smoking is not good for you, it speeds-up progressive MS

As an MSer can you afford to continue smoking? #ClinicSpeak #MSResearch #MSBlog 

“If you are a smoker and develop MS and continue to smoke you need to read this post and think seriously about what you want out of life. We talk about developing effective treatments to slow down the progression of MS and ignore the obvious. The first study below suggests that simply stopping smoking will have a major impact on the outcome of your MS. Can you ignore this? Do you want to stop smoking? If you do please ask your GP or family doctor to refer you to a stop smoking clinic; please note it is very difficult to stop smoking without professional help.”

“How smoking speeds up the onset and rate of progressive MS is unknown. It may simply ramp up the autoimmune process, reduce recovery mechanisms in the brain and spinal cord or stimulate the development of comorbidities in particular vascular disease. Although finding out how smoking speeds up the development of progressive MS is clearly of academic interest to me; it does not detract from the obvious therapeutic implications of the need to stop smoking.”

“The effect of smoking on progressive MS may be independent of it being a risk factor for developing MS in the first place. This is why we need more research in this area to see what it is about smoking that triggers MS. Based on other Swedish data it appears that it is something is smoked tobacco that is to blame. In Sweden use of snuff, or non-smoked tobacco, does not increase your risk of getting MS. It will be interesting if the use of e-cigarettes alters your risk of getting MS and other autoimmune diseases. The problem with e-cigarettes is that most users continue to smoke real cigarettes, albeit fewer cigarettes. Let’s hope e-cigarettes, which are simply a nicotine delivery system, help addicted smokers kick the habit and slow their disability progression.”  

“The second Swedish study below confirms my previous estimates that if we get the population not to start smoking in the first place we can prevent 1 in 5 future people from developing MS. This is why it upsets me so much when my own children smoke. Even more worrying is that if you are loaded with the correct genetic factors that predispose you to developing MS your odds of getting MS increase dramatically if you smoke. The latter is more reason to make sure your brothers and sisters, children, nephews and nieces don’t smoke. I always this is easier said than done.”

Ramanujam et al. Effect of Smoking Cessation on Multiple Sclerosis Prognosis. JAMA Neurol. 2015 Oct 1;72(10):1117-1123.

IMPORTANCE: Smoking tobacco is a well-established risk factor for multiple sclerosis (MS), a chronic inflammatory disorder of the central nervous system usually characterized by bouts and remissions and typically followed by a secondary progressive (SP) course. However, it is not clear whether smoking after diagnosis is detrimental.

OBJECTIVE: To determine whether smoking after MS diagnosis is associated with a change in time to SP disease.

DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of patients with prevalent MS who smoked at diagnosis (n = 728) taken from the Genes and Environment in Multiple Sclerosis Study, which consists of patients from the Swedish National MS Registry. The study entrance date was at time of first-year smoking. The study was conducted between November 2008 and December 2011, with patient environmental data collected from November 2009 to March 2011 via questionnaire. Study participants were from all counties in Sweden diagnosed as having MS at the time of the Genes and Environment in Multiple Sclerosis Study and registered in the Swedish National MS Registry. Patients with MS with relapsing-remitting disease course or SP were included. These patients’ conditions were diagnosed according to the McDonald criteria and the patients responded to recruitment letters with detailed questionnaires.

EXPOSURE: Smoking, considered yearly after diagnosis and combined into a time-invariant covariate before diagnosis.

MAIN OUTCOMES AND MEASURES: Time to SPMS, measured using an accelerated failure time model, with smoking as a time-varying covariate. Other covariates included sex, age at diagnosis, snuff use, and smoking before diagnosis.

RESULTS: The optimized model illustrated that each additional year of smoking after diagnosis accelerated the time to conversion to SPMS by 4.7% (acceleration factor, 1.047; 95% CI, 1.023-1.072; P < .001). Kaplan-Meier plots demonstrated that those who continued to smoke continuously each year after diagnosis converted to SPMS faster than those who quit smoking, reaching SP disease at 48 and 56 years of age, respectively.

CONCLUSIONS AND RELEVANCE: This study provides evidence that continued smoking is associated with an acceleration in time to SPMS and that those who quit fare better. Therefore, we propose that patients with MS should be advised to stop smoking once a diagnosis has been made, not only to lessen risks for comorbidities, but also to avoid aggravating MS-related disability.

Hedström et al. Smoking is a major preventable risk factor for multiple sclerosis. Mult Scler. 2015 Oct 12. pii: 1352458515609794.

BACKGROUND: Both smoking and exposure to passive smoking have repeatedly been associated with increased multiple sclerosis (MS) risk, but have never before been studied together. We assessed the public health impact of these factors.

METHODS: In a Swedish population-based case-control study (2455 cases, 5336 controls), we calculated odds ratios of developing MS associated with different categories of tobacco smoke exposure, together with 95% confidence intervals, by using logistic regression. The excess proportion of cases attributable to smoking and passive smoking was calculated as a percentage.

RESULTS: Both smoking and exposure to passive smoking contribute to MS risk in a dose-dependent manner. At the population level, 20.4% of all cases were attributable to smoke exposure. Among subjects carrying the genetic risk factor HLA-DRB1*15 but lacking HLA-A*02, 41% of the MS cases were attributable to smoking.

CONCLUSIONS: From a public health perspective, the impact of smoking and passive smoking on MS risk is considerable. Preventive measures in order to reduce tobacco smoke exposure are, therefore, essential. In particular, individuals with a history of MS in the family should be informed regarding the impact of smoking on the risk of MS, and the importance of preventing their children from being exposed to passive smoke.

About the author

Prof G

Professor of Neurology, Barts & The London. MS & Preventive Neurology thinker, blogger, runner, vegetable gardener, husband, father, cook and wine & food lover.


  • I used to go night clubbing and pubs before the smoking ban. I must have passive smoked quite a bit, my clothes and hair would stink of smoke when I got home.
    About 17 years ago went on a plane to the Seychelles on holiday and they had an inflight smoking section on the plane. Seems crazy to have allowed inflight smoking for health of people and safety of aircraft.

  • I am shocked how many people still smoke. I was at the hospital today and at the bus stop five people were smoking, the smoke was blowing my way. Then there's the nurses i've seen at the back of the hospital outside having a smoking break.

    • I've been weighed so many time recently by obese nurses. I've also had to endure discussions with an obese doctor about my weight loss. I find it uncomfortable. Maybe Jeremy Hunt could have a think about busy nurses an doctors having to grab a bag of crisps or some other unhealthy snack for lunch, because they don't have time. I don't know why this is on sale in hospitals anyway.

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