Conference Coverage

Smoking impairs cognition and shrinks brain volume in MS



Here’s another good reason for smokers with multiple sclerosis (MS) to quit the tobacco habit: Their cognitive function may get a boost as a result, Ebtesam Alshehri, MD, said at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis.

Dr. Ebtesam Alshehri, a neurologist and clinical neuroimmunology fellow at the Cleveland Clinic Bruce Jancin/MDedge News

Dr. Ebtesam Alshehri

“We found that smokers have reduced Processing Speed Test scores compared with nonsmokers. They also have more brain atrophy. And we found that former smokers had intermediate results between current smokers and never smokers, suggesting that there is a benefit of smoking cessation early in the course of the disease,” explained Dr. Alshehri, a clinical neuroimmunology fellow at the Cleveland Clinic.

Dr. Alshehri and colleagues presented a cross-sectional study of 997 patients with MS. At the Cleveland Clinic, patients with MS routinely undergo the Processing Speed Test (PST) – an electronic version of the Symbol Digit Modalities Test – at each clinical visit as a means of assessing cognitive function. All 997 patients also underwent quantitative brain MRI within 90 days of their cognitive function test. The study population consisted of 520 never smokers, 335 ex-smokers, and 142 current smokers. Seventy-seven percent of the patients had relapsing-remitting MS, and most of the rest had progressive disease.

The impetus for this hypothesis-generating study was a recognition that while smoking has previously been reported to be a risk factor for MS and has also been associated with accelerated progression of disability in patients who already have the disease, the impact of smoking on cognition and brain atrophy in the MS population has been a murky area, according to Dr. Alshehri.

In a multivariate analysis adjusted for age, disease duration, and disease course, smoking status was an independent predictor of PST score. Former smokers scored an average of 3.6 points lower than never smokers, and current smokers scored 5.9 points lower than the never smokers. Similarly, former smokers appeared better off than current smokers in terms of brain atrophy as measured by whole brain function on MRI: The ex-smokers had significantly greater brain atrophy than that of never smokers, an effect that was magnified in current smokers.

For Dr. Alshehri, these findings contain an important message for physicians: “I think as clinicians we should ask our patients with MS about tobacco use at each visit, remind patients about the risks of smoking and the negative impact not only on their general health, but also the impact on disease progression and disability worsening, encourage patients to stop smoking, and provide them with this encouraging data.”

She reported having no financial conflicts regarding this study, which was conducted free of commercial support.

SOURCE: Alshehri E et al. ECTRIMS 2019. Abstract P461.

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