The impact of cigarette smoking on cognitive processing speed and brain atrophy in multiple sclerosis

Abstract

Background: Smoking is associated with an increased risk of multiple sclerosis (MS) and disability worsening. The relationship between smoking, cognitive processing speed, and brain atrophy remains uncertain. Objective: To quantify the impact of smoking on processing speed and brain volume in MS and to explore the longitudinal relationship between smoking and changes in processing speed. Methods: A retrospective study of MS patients who completed the processing speed test (PST) between September 2015 and March 2020. Demographics, disease characteristics, smoking history, and quantitative magnetic resonance imaging (MRI) were collected. Cross-sectional associations between smoking, PST performance, whole-brain fraction (WBF), gray matter fraction (GMF), and thalamic fraction (TF) were assessed using multivariable linear regression. The longitudinal relationship between smoking and PST performance was assessed by linear mixed modeling. Results: The analysis included 5536 subjects of whom 1314 had quantitative MRI within 90 days of PST assessment. Current smokers had lower PST scores than never smokers at baseline, and this difference persisted over time. Smoking was associated with reduced GMF but not with WBF or TF. Conclusion: Smoking has an adverse relationship with cognition and GMF. Although causality is not demonstrated, these observations support the importance of smoking cessation counseling in MS management.

Sex differences in multiple sclerosis relapse presentation and outcome: a retrospective, monocentric study of 134 relapse events

“…An interrelation of these two factors is likely. However, whether the higher EDSS in men is driven by the longer disease duration or additionally influenced by smoking behavior, as robustly shown before, 15 – 20 cannot be answered by our data. Of note, persons experiencing their first clinical relapse (31.3%) were not included in this pre-relapse EDSS, which is why we refrained from calculating the EDSS difference pre- to during relapse.…”

“… 3 , 9 Taken together, these data with poorer relapse recovery and more motor involvement in men might suggest a general effect of male sex on higher disability progression 11 indicating that additional factors must play a role. Among the latter surely are patient age, disease duration, and disease-modifying treatment (DMT), 2 , 10 , 13 but also individual and possibly gender-influenced behavioral factors, especially smoking 15 – 20 and obesity. 21 …”

Risk Factors for Cognitive Impairment in Multiple Sclerosis Patients

“…Table 1 summarizes the major risk factors associated with cognitive impairment in MS, highlighting possible underlying pathophysiological and relevant references published in the last ten years. Diet Gut-brain axis Renin-angiotensin-aldosterone system [41][42][43][44] Lack of physical exercise To be determined [45,46] Smoking Increased plaque load Reduced gray matter fraction [47][48][49][50] Vitamin D deficiency…”

“…Regarding the smoking-cognitive impairment association, even older studies assess this negative link [48]. MRI studies in MS smokers showed a correlation between smoking, MS, and an increased plaque load, together with reduced brain parenchyma and gray matter fractions [49]. Moreover, smoking cessation showed significant improvement in the evolution of MS, slowing the rate of motor disability deterioration, equivalent to the natural MS progression in non-smokers [50].…”