Smoking Worsens Multiple Sclerosis

ByABC News
August 17, 2009, 8:18 PM

Aug. 18 -- MONDAY, Aug. 17 (HealthDay News) -- Patients with multiple sclerosis who smoke appear to be at higher risk for the brain lesions linked with the disease and for brain shrinkage, new research suggests.

"Our study is showing that MS is more destructive as seen on MRI in smokers than nonsmokers," said study co-author Dr. Bianca Weinstock-Guttman, director of the Baird MS Center and Pediatric MS Center of Excellence at the State University of New York at Buffalo. The study appears in the Aug. 18 issue of Neurology.

Researchers have known that smoking boosts the risk of getting MS, but the effect of smoking after diagnosis has been studied less often.

MS, a chronic disease that attacks the central nervous system, including the spinal cord, brain and optic nerve, affects about 400,000 Americans, according to the National Multiple Sclerosis Society. Symptoms can be mild, such as limb numbness, or severe, such as loss of vision or paralysis.

The different courses that MS can take include relapsing and remitting, progressive, or progressive and relapsing, the society says.

Weinstock-Guttman and her colleagues evaluated 368 MS patients, average age 44, who had been diagnosed about 12 years earlier. Of the 368 patients, 240 had never smoked, 96 smoked currently and 32 had smoked in the past.

All patients were evaluated clinically and had an MRI to monitor the disease process and evaluate the effects of treatments. The MRI measured the size of the MS-related brain lesions and the brain shrinkage that can occur with age and with MS.

Smokers with MS had nearly 17 percent more brain lesions than nonsmokers with MS. Smokers with MS also had more brain tissue shrinkage.

Exactly why smoking has this effect isn't known, Weinstock-Guttman said. However, she suspects that nicotine may disrupt the blood-brain barrier, and the toxins in cigarette smoke may be a constant, inflammatory irritant. "Smokers aren't able to repair themselves" due to the constant presence of the toxins from cigarette smoke, she explained. So, the inflammation that is characteristic of the disease never goes away, setting patients up for worsening disease.