Association Between Cigarette Smoking and Multiple Sclerosis

Abstract

ultiple sclerosis (MS) is a chronic neurologic disorder characterized by demyelination and axonal loss in the central nervous system (CNS). 1 Environmental factors play a central role in the cause of MS. The most important environmental risk factors include cigarette smoking, Epstein-Barr virus infections, vitamin D deficiency, and obesity. 2,3 Cigarette smoking is a widespread habit with 2 billion consumers worldwide-a total of 5.8 trillion cigarettes are consumed each year. Smoking is associated with an increased risk of MS. Patients with MS have a worse long-term prognosis and greater rates of brain atrophy than their nonsmoking counterparts. 4 Also, smoking is more prevalent in patients with MS than in the general population. 5 Our review summarizes the current literature on the outcomes of cigarette smoking in patients with MS. We focus on how smoking affects the immune and nervous systems. We then comment on how these insights inform how smoking affects MS risk and prognosis. In addition, we outline the role of counseling and smoking cessation for patients with MS. MethodsWe conducted a narrative review by researching the available English-language literature studies. We used search terms including multiple sclerosis, cigarette smoking, passive smoking, tobacco, and waterpipe smoking. The literature review was performed using

Smoking and disability progression in multiple sclerosis

“…Several studies have observed increased Expanded Disability Status Scale (EDSS) scores and Multiple Sclerosis Severity Score (MSSS) among smokers compared to nonsmokers [1]. Smoking has been associated with the rate of conversion from relapsing remitting to secondary progressive disease, and with time from MS onset to fixed disability milestones as measured by EDSS [1]. The association is supported by the presence of a dose-response effect of smoking on disability in terms of EDSS and MSSS changes [2].…”

“…However, a variety of methods and outcome measures have been used, making it difficult to draw conclusions across studies. Several studies have observed increased Expanded Disability Status Scale (EDSS) scores and Multiple Sclerosis Severity Score (MSSS) among smokers compared to nonsmokers [1]. Smoking has been associated with the rate of conversion from relapsing remitting to secondary progressive disease, and with time from MS onset to fixed disability milestones as measured by EDSS [1].…”

“…Each additional year of smoking after the diagnosis has been estimated to accelerate the time to conversion by 4.7% [4]. Smoking has also been associated with magnetic resonance imaging (MRI) markers of disease progression such as increased T2-weighted lesion volume and greater brain atrophy [1]. Furthermore, smoking may affect the efficacy of disease-modifying drugs, and contribute to the induction of antidrug antibodies to biological therapies, which may abrogate the therapeutic effect of the treatment [5].…”

“…Studies exploring a potential impact of smoking on disease progression in patients with clinically isolated syndrome have been more conflicting. Generally, studies using self-reported smoking habits have detected an association between smoking and disease progression, whereas cotinine levels have not correlated well with disease progression in studies using cotinine as a measure of tobacco consumption [1].…”

Early Postnatal Tobacco Smoke Exposure Aggravates Experimental Autoimmune Encephalomyelitis in Adult Rats

“…Tobacco smoke has received increasing attention as a potential environmental risk factor for MS (Öberg et al, 2011; Carreras et al, 2019). Adult population case-control studies have shown that smoking or exposure to environmental tobacco smoke (ETS) promotes the disease progression and increases the recurrence of MS (Alphonsus and D’Arcy, 2019; Rosso and Chitnis, 2020). However, evidence for the impact of early-life exposure to ETS on adulthood MS development is not certain and even conflicting in the literature (Montgomery et al, 2008; Pantazou et al, 2015; Pronovost and Hsiao, 2019).…”