Smoking tobacco is a well-established risk factor for multiple sclerosis, a chronic inflammatory disorder of the central nervous system characterized by flare-ups and remissions and typically followed by a secondary progressive course. The purpose of this study was to determine whether smoking after multiple sclerosis diagnosis is associated with a change in time to secondary progressive disease.
Patients with prevalent multiple sclerosis who smoked at diagnosis (n = 728) were 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 found that each additional year of smoking after diagnosis accelerated the time to conversion to secondary progressive multiple sclerosis by 4.7%. Those who continued to smoke continuously each year after diagnosis converted to secondary progressive multiple sclerosis faster than those who quit smoking, reaching secondary progressive disease at 48 and 56 years of age, respectively.
The authors concluded that continued smoking is associated with acceleration in time to secondary progressive multiple sclerosis and that those who quit fare better. They suggest that patients with multiple sclerosis should be advised to stop smoking once a diagnosis has been made, not only to lessen risks for comorbidities, but also to avoid aggravating multiple sclerosis-related disability.
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Ramanujam R, Hedström AK, Manouchehrinia A, Alfredsson L, Olsson T, Bottai M and Hillert J: Effect of Smoking Cessation on Multiple Sclerosis Prognosis. JAMA Neurol. 72(10): 1117-1123 (2015).
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http://www.ncbi.nlm.nih.gov/pubmed/26348720