Background: Cigarette smoking has been linked to higher susceptibility and increased risk of progressive multiple sclerosis (MS). The effects of smoking on MRI characteristics of patients with MS have not been evaluated.
Objectives: To compare the MRI characteristics in cigarette smoker and nonsmoker patients with MS.
Methods: We studied 368 consecutive patients with MS (age 44.0 +/-SD 10.2 years, disease duration 12.1 +/- 9.1 years) comprising 240 never-smokers and 128 (34.8%) ever-smokers (currently active and former smokers). The average number of packs per day smoked (+/-SD) was 0.95 +/- 0.65, and the mean duration of smoking was 18.0 +/- 9.5 years. All patients obtained full clinical and quantitative MRI evaluation. MRI measures included T1, T2, and gadolinium contrast-enhancing (CE) lesion volumes (LVs) and measures of central, global, and tissue-specific brain atrophy. The associations between smoking status and MRI measurements were assessed in regression analysis.
Results: Smoking was associated with increased Expanded Disability Status Scale (EDSS) scores (p = 0.004). The median EDSS scores (interquartile range) in the ever-smoker group and the active-smoker group were both 3.0 (2.0), compared with 2.5 (2.5) in never-smokers. There were adverse associations between smoking and the lesion measures including increased number of CE lesions (p < 0.001), T2 LV (p = 0.009), and T1 LV (p = 0.003). Smoking was associated with decreased brain parenchymal fraction (p = 0.047) and with increases in the lateral ventricle volume (p = 0.001) and third ventricle width (p = 0.023).
Conclusions: Smoking is associated with increased blood-brain barrier disruption, higher lesion volumes, and greater atrophy in multiple sclerosis.