Smoking..Still time to Stop!

What can we do to get MSers to stop smoking? #MSBlog #MSResearch

Epub: Manouchehrinia A, Tench CR, Maxted J, Bibani RH, Britton J, Constantinescu CS. Tobacco smoking and disability progression in multiple sclerosis: United Kingdom cohort study. Brain. 2013 Jun 11.

Tobacco smoking has been linked to an increased risk of multiple sclerosis. However, to date, results from the few studies on the impact of smoking on the progression of disability are conflicting. The aim of this study was to investigate the effects of smoking on disability progression and disease severity in a cohort of patients with clinically definite multiple sclerosis. We analysed data from 895 patients (270 male, 625 female), mean age 49 years with mean disease duration 17 years. Forty-nine per cent of the patients were regular smokers at the time of disease onset or at diagnosis (ever-smokers). Average disease severity as measured by multiple sclerosis severity score was greater in ever-smokers, by 0.68 (95% confidence interval: 0.36-1.01). The risk of reaching Expanded Disability Status Scale score milestones of 4 and 6 in ever-smokers compared to never-smokers was 1.34 (95% confidence interval: 1.12-1.60) and 1.25 (95% confidence interval: 1.02-1.51) respectively. Current smokers showed 1.64 (95% confidence interval: 1.33-2.02) and 1.49 (95% confidence interval: 1.18-1.86) times higher risk of reaching Expanded Disability Status Scale scores 4 and 6 compared with non-smokers. Ex-smokers who stopped smoking either before or after the onset of the disease had a significantly lower risk of reaching Expanded Disability Status Scale scores 4 (hazard ratio: 0.65, confidence interval: 0.50-0.83) and 6 (hazard ratio: 0.69, confidence interval: 0.53-0.90) than current smokers, and there was no significant difference between ex-smokers and non-smokers in terms of time to Expanded Disability Status Scale scores 4 or 6. Our data suggest that regular smoking is associated with more severe disease and faster disability progression. In addition, smoking cessation, whether before or after onset of the disease, is associated with a slower progression of disability.

The evidence against smoking is mounting. It is well established that smoking increases the risk of MS (n.b. this is not the same as saying that smoking causes MS). The evidence regarding smoking and disease progression has previously been less rigorous. This study demonstrates that smokers reach disease milestones more rapidly than non-smokers. Interestingly, people who stop smoking (even after diagnosis) appear to have slightly slower disease progression; their disease behaves more like that of a non-smoker.

We don’t know why this is. One theory as to why smoking affects MS is that there is some evidence of a biological interaction between smoking and EBV, as nicotine metabolism has a shared pathway with EBV activation. But this is all speculation – nothing has been conclusively demonstrated. Whilst evidence of association and influence on MS grows, the why and how remain…

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  • So is this study related to all the toxic ingredients of the cigarette or is it only to the nicotine? I recently stopped smoking traditional cigarettes and now I am using the E-cigarette as a step down. If anyone could answer this I would appreciate it.

  • I just read of a study looking at the toxin acrolein, found in tobacco smoke and produced in the body after nerve cells have been damaged, which triggers a response which worsens the damage to the nerves.

  • Hi Mandy – the problem is that we don't know! It is likely to be related to inhaling smoke, as there doesn't seem to be the same effect with snuff, which is chewing tobacco. My guess (but it is only a guess) is that it is likely to be a number of inhaled substances in cigarettes, rather than just one.
    There is an association between smoking and low vitamin D, I'm not sure it is a causal one though (happy to be proved wrong if i have missed some evidence!)


    • I'd have thought that with smokers these days having to puff away outside their workplace in the open air, their sunlight exposure ought to be higher than their colleagues so it must be something (if lower levels in smokers is correct) to do with what's in cigarette smoke.

    • There are a number of research articles about tobacco smoke altering the way Vitamin D is metabolised.

    • Yes, all people should worry about 2nd-hand smoke. You need to do everything to maintain and maximise your general health.

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