Researchers at Boston Medical School reported in the July issue of Archives of Neurology that they surveyed 1,465 patients with multiple sclerosis. The average age of the respondents was 42 years, and the average duration of the disease was 9.4 years. Of them, 257 still smoked, 428 had smoked but had since quit, and 780 had never smoked. At the beginning of the survey, the MS disease was already more severe in the smokers than in the other 2 groups. The researchers then returned at average intervals of 3 years to determine the progression of MS in the respondents. It was found that the patients who smoked had the highest probability of having a worsening of their MS compared to the other 2 groups. The researchers thus concluded that smoking exacerbates MS.