Smoking Linked to Lesions and Brain Shrinkage in Multiple Sclerosis

Allison Gandey

August 20, 2009

August 20, 2009 — People with multiple sclerosis who smoke have higher lesion volumes, more atrophy, and are at greater risk for blood–brain barrier disruption, say researchers. Reporting in the August 18 issue of Neurology, investigators show nearly 17% more brain lesions in smokers, 13% larger ventricles, and a smaller brain size compared with nonsmokers.

"Findings from our study suggest that smoking is an important contributor to disability progression in patients with multiple sclerosis," lead author Robert Zivadinov, MD, from the University of New York School of Medicine and Biomedical Sciences in Buffalo told Medscape Neurology. "Ours is the first study to demonstrate that smoking can promote brain tissue injury in multiple sclerosis patients, and this was surprising."

The researchers point to evidence suggesting that both genetic and environmental factors are involved in multiple sclerosis susceptibility and disease progression. They suggest that cigarette smoking is one of the most compelling environmental risk factors linked to the development and worsening of disease. Other environmental risk factors include sun exposure, vitamin D deficiency, and Epstein-Barr infections.

The current analysis included 368 people. All patients obtained full clinical and quantitative magnetic resonance imaging. Participants were an average age of 44 years, and most had been diagnosed with multiple sclerosis for about 12 years.

Patients were asked about their smoking history: 240 were nonsmokers, 96 were current smokers, and another 32 were past smokers. Investigators found that smoking was associated with increased Expanded Disability Status Scale scores (P = .004).

Expanded Disability Status Scale

Smoking Median Scores (Interquartile Range)
Ever 3.0 (2.0)
Active 3.0 (2.0)
Never 2.5 (2.5)

Current smokers had more than 10 cigarettes per day in the 3 months leading up to the study, past smokers had cigarettes for at least 6 months sometime before the start of the study, and the average current smoker in the study had been smoking for 18 years.

There were adverse associations between smoking and lesion measures. This included an increased number of contrast-enhancing lesions (P < .001), T2 lesion volume (P = .009), and T1 lesion volume (P = .003). Smoking was also associated with a decreased brain parenchymal fraction (P = .047) and with increases in the lateral ventricle volume (P = .001) and third ventricle width (P = .023).

The findings are similar to those of another study published in the July issue of the Archives of Neurology (2009;66:858–864). As previously reported by Medscape Neurology, investigators found that smoking contributes to rapid disease progression.

Rapid Disease Progression

The study included 1465 patients diagnosed with multiple sclerosis who completed a self-administered smoking questionnaire while being treated at the Partners Multiple Sclerosis Center at Brigham and Women's Hospital in Boston, Massachusetts.

Investigators found that current smokers had significantly more severe disease at baseline and also progressed at a faster rate. "So if smokers had relapsing-remitting multiple sclerosis, they converted to a progressive course sooner than those who had never smoked," explained study author Alberto Ascherio, MD, from Harvard Medical School in Boston.

Asked for comment when the study was first published, Lily Jung, MD, from the Swedish Neuroscience Institute, in Seattle, Washington, and member of the American Academy of Neurology, said, "This is just more ammunition for telling patients that to stop smoking is the easiest thing they can do to treat their multiple sclerosis."

Kicking the Habit

Dr. Jung says smoking should be discussed "before you even go into the whole discussion about disease-modifying therapies and their costs, fears of injections, and side effects." Quitting the habit, she said, gives patients "a better fighting chance" to cope with disease.

The biological basis for the link between smoking and multiple sclerosis has not yet been identified. "In addition to nicotine," Dr. Zivadinov said, "cigarette smoke contains hundreds of potentially toxic components including tar, carbon monoxide, and polycyclic aromatic hydrocarbons."

He says the study stresses the importance of antismoking education in schools — where many smokers start. "Increased antismoking education in schools and more targeted smoking cessation programs for patients with multiple sclerosis should be further encouraged and supported."

This study was funded by the National Multiple Sclerosis Society. Lead author Dr. Robert Zivadinov has disclosed receiving funds from Teva Neurosciences, Biogen Idec, Aspreva, Pfizer, EMD Serono, Genzyme, and Aspreva.

Neurology. 2009;73:504–510.

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