Quitting smoking or moving to snuff may help slow MS progression

Smoking and exposure to secondhand smoke are both associated with significantly faster disease progression in people with multiple sclerosis (MS), but snuff, a smokeless tobacco product placed behind the upper lip, seems to slow MS progression, a study in Sweden suggests.

Findings also linked smoking and secondhand exposure, also known as passive smoking, with faster cognitive decline, and both increased the risk of disability worsening. However, patients who quit smoking after their diagnosis had similar outcomes as those who had never smoked.

Thus, stopping smoking after diagnosis or replacing smoking with moist snuff may help modify the course of MS and reduce its progression in patients, researchers suggest.

“Nicotine replacement therapy could be an attractive way to increase the chance of quitting smoking post diagnosis,” they wrote.

The study, “Influence of oral tobacco versus smoking on multiple sclerosis disease activity and progression,” was published in the Journal of Neurology, Neurosurgery & Psychiatry.

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Smoking is known to negatively affect MS severity and progression, with patients who smoke having a greater risk of attaining certain disability milestones, showing greater MRI activity, and experiencing higher rates of brain atrophy (shrinkage). Patients also seem to experience more fatigue, depression, and worse quality of life.

Passive smoking has been found to increase the risk of developing MS, but its impact on disease progression remains to be established.

Because smoking is a modifiable risk factor in MS, quitting smoking is important to slow MS progression. A possible strategy is using a nicotine replacement therapy, such as moist snuff, a traditional Scandinavian smokeless tobacco that delivers high amounts of nicotine without irritating the airways.

These products have not been linked with MS development, but whether they have an impact on disease progression has not been established, so it is unknown if snuff could be a safe alternative for MS patients trying to quit smoking.

Researchers in Sweden set out to explore the associations between snuff and MS progression, and determine how passive smoking and quitting smoking can affect disease outcomes. Their study included data from 9,089 MS patients followed up in two population-based studies in Sweden and with available disability data in the Swedish MS registry.

The mean age of the patients was 37.6 years and the majority were women (72%). They were grouped into one of three categories according to their smoking habits at the time of their MS diagnosis: never smokers (40.4%), current smokers (31.9%), and past smokers (27.7%).

At the time of the first disability assessment after diagnosis (baseline), smokers had significantly higher Expanded Disability Status Scale (EDSS) scores and worse cognitive function than non-smokers. Compared with never smokers, both current and past smokers also became more disabled faster, as determined by faster increased EDSS scores over time.

Both current smoking and current exposure to passive smoking negatively impacts disease progression in patients with MS.

Current smokers at high risk for worsening disability

Notably, patients who were current smokers at baseline were 13% more likely than never smokers to experience confirmed disability worsening — defined as the presence of relapses, new or enlarging lesions, or EDSS increases — and were 31% more likely to reach an EDSS score of 4, indicating significant disability.

However, past smoking showed no significant associations with these outcomes, indicating that patients who stopped smoking before or immediately after a diagnosis had similar disease progression rates as never smokers.

In fact, compared with non-smokers at baseline, patients who continued smoking had a 21% higher risk of confirmed disability worsening, and a 44% higher risk of reaching an EDSS score of 4. Those who kept smoking also had a higher risk of physical, psychological, and cognitive decline than non-smokers.

No significant differences were observed between those who quit smoking after diagnosis and non-smokers at baseline.

About 61% of the patients reported past daily exposure to secondhand smoke, with a mean exposure time of 15.9 years. Of those, 1,177 were currently exposed to secondhand smoke and 4,399 had been in the past. The remaining 3,513 reported they had never been exposed to secondhand smoke.

At baseline, patients currently exposed to secondhand smoke had higher EDSS scores, but this was not observed in people with past exposure. However, both groups experienced a faster disability progression.

Compared with past exposure to secondhand smoke, current exposure was associated with an 18% higher risk of confirmed disability worsening and a 79% higher risk of an EDSS of 4. Current exposure was also linked to more physical and psychological worsening, but did not appear to affect cognitive decline.

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Snuff use associated with lower risk of disability worsening

“In conclusion, both current smoking and current exposure to passive smoking negatively impacts disease progression in patients with MS,” the researchers wrote.

Snuff use was reported by 1,549 patients, of whom 1,097 were current users and had been using it for 9.4 years on average, and the remaining were past users and had used snuff for 17.8 years. After adjusting for smoking and passive smoking, snuff use was significantly associated with less disability and better cognitive function at baseline.

Snuff users (both current and past) also had a significant, 16% lower risk of confirmed disability worsening, and a 19% lower risk of reaching an EDSS of 4 compared with never users.

While the findings confirm the negative impact of smoking on MS progression, more than 80% of those who were smokers when diagnosed with MS continued to smoke five years after their diagnosis.

“Efforts should thus be made to better understand patient-specific barriers to stopping smoking and provide smoking cessation support for patients with MS. Nicotine replacement therapy could be part of such cessation support,” the researchers concluded.