MONDAY, July 13 (HealthDay News) -- In addition to the well-known hazards of smoking, research now suggests that the dangerous habit causes a more rapid progression of multiple sclerosis.
The new findings are from a study that included 1,465 multiple sclerosis (MS) patients, average age 42, who had had MS for an average of 9.4 years. There were 257 current smokers, 428 past smokers and 780 participants who had never smoked.
At the start of the study, current smokers had significantly more severe disease and were also more likely to have primary progressive MS (a steady decline in health status), rather than relapsing-remitting MS (alternating periods with and without symptoms).
The Boston researchers tracked a group of 891 patients for an average of three years to identify how many changed from relapsing-remitting MS to secondary progressive MS, which is a steady decline that develops after a period of relapsing-remitting MS. During the follow-up, this change was seen in 20 of 154 smokers, 20 of 237 ex-smokers and 32 of 500 never-smokers.
"The conversion from relapsing-remitting MS to secondary progressive MS occurred faster in current smokers compared with never-smokers, but was similar in ex-smokers and never-smokers," according to Brian C. Healy of Brigham and Women's Hospital, Harvard Medical School and Massachusetts General Hospital, and colleagues.
The study was reported in the July issue of Archives of Neurology.
The findings "support the hypothesis that cigarette smoking has an adverse effect on progression of MS as measured by clinical and MRI outcomes," the study authors concluded. "Although causality remains to be proved, these findings suggest that patients with MS who quit smoking may not only reduce their risk of smoking-related diseases but also delay the progression of MS."