In a further confirmation of the negative impacts of cigarette smoking by people who have multiple sclerosis, researchers recently reported finding links between smoking and brain tissue damage observed on MRI (magnetic resonance imaging) scans of 368 people with MS. Robert Zivadinov, MD, PhD, and Murali Ramanathan, PhD (State University of New York, Buffalo) and colleagues report their findings in Neurology (2009;73:504-510). A second study also reports negative effects of tobacco smoking, but cites no association between the use of Swedish snuff and risk for MS. Anna K. Hedström, MD, and colleagues (Karolinska Institute, Stockholm) report on a study of 902 people with MS in Neurology (2009;73:696–701).
Background: MS is not contagious or directly inherited, but scientists have identified factors that help determine whether a person will develop MS. These factors include genes, gender, age, geography, and ethnic background. Previous studies have suggested that cigarette smoking increases a person’s risk for developing MS. Some studies have also hinted that smoking could contribute to disease progression (worsening), and a recent study found that MS disability progressed more quickly in smokers, and suggested that quitting may delay MS progression.
The Buffalo Study: The team administered a questionnaire on smoking history and current smoking habits to 368 consecutive people with MS during the course of routine clinical follow-up visits, which showed that 240 had never smoked, and 128 were current or former smokers. The investigators compared participants’ MRI scans that measured disease activity and brain tissue atrophy (shrinkage), and the results were correlated with smoking history/habits and clinical characteristics of their disease. Smoking (active smokers or ever-smokers) was associated with increased physical disability as measured by the EDSS (Expanded Disability Status Scale) over that observed for never-smokers, supporting previous studies. Smokers also had greater amounts of tissue damage (lesions) observed on gadolinium-enhanced MRI (which highlights areas of breakdown in the blood-brain barrier that indicate inflammation); a greater volume of brain lesions; and more brain atrophy.
The Stockholm Study: The team looked at the incidence of MS tobacco smokers and the users of Swedish snuff in a sample of 902 people with MS and 1,855 people without the disease. Smokers had an increased risk of developing MS, and the risk increased with the cumulative amount of smoking. There was an apparent association between using snuff and decreased risk of MS. The authors suggest that this implies that nicotine – which is an ingredient of both – may not be the culprit for the clear increase in risk among cigarette smokers; more research is necessary to determine the molecular mechanisms for this risk increase. It is important to note that Swedish snuff, and all oral tobacco, can cause cancer of the mouth, pancreas, and esophagus, as well as gum disease, destruction of the bone sockets around the teeth, and tooth loss.
Comment: These studies add new information to the case against smoking for people with MS, providing details on how smoking may affect underlying tissue damage. The National Institutes of Health provides resources to help quit smoking: visit smokefree.gov or call 1-800-QUITNOW (1-800-784-8669). Read more about healthy living with MS.