Study links cigarette smoking to faster disability progression in MS

Smoking cigarettes may speed up disease progression in people with multiple sclerosis (MS), while alcohol consumption showed no clear harmful effect, according to a long-term study involving more than 1,300 adults in Germany.

Researchers found that smokers, particularly light smokers, were significantly more likely to experience worsening disability and slower walking speed over six years than nonsmokers.

Although alcohol consumption was linked to a lower risk of disease progression, researchers cautioned that the results could reflect “reverse causation,” meaning people with milder disease may be more likely to continue drinking alcohol, while those with worsening symptoms may choose to stop.

“This study provides further evidence that smoking cigarettes accelerates MS progression and that [people with MS] should be advised to quit smoking,” researchers wrote. “However, this negative impact could not be demonstrated for alcohol consumption. Reverse causation cannot be ruled out and further research in this area is warranted.”

The study, “Impact of tobacco and alcohol consumption on disease progression and MRI in people with multiple sclerosis: results of the prospective cohort study NationMS,” was published in Therapeutic Advances in Neurological Disorders.

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Smoking has consistently been linked to higher risk of developing MS

What causes MS, a progressive disease that damages the brain and spinal cord, remains unclear. However, growing evidence suggests that certain lifestyle habits may influence both the risk of developing the disease and how quickly it progresses.

Among these factors are cigarette smoking and alcohol consumption. Smoking has consistently been linked to a higher risk of developing MS and to worse outcomes after diagnosis, including more frequent relapses, faster disease progression, and a greater burden of brain lesions.

The role of alcohol, however, remains less clear. While some studies have suggested that moderate alcohol consumption may be associated with slower disease progression, others have found no such benefit.

To better understand the long-term effects of these lifestyle habits on MS progression, researchers analyzed data from 1,374 adults enrolled between 2010 and 2017 in the German NationMS study, a large ongoing observational study that has been following people with early MS since 2010.

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Disability worsened more quickly over time in smokers

At the start of the study, 66.1% of participants did not smoke, while 32% reported smoking to varying degrees. Regarding alcohol, 26.6% said they did not drink, 67.6% reported drinking occasionally, and 4.2% reported drinking regularly.

The researchers assessed three key measures of disease progression: overall disability using the Expanded Disability Status Scale (EDSS), walking ability using the Timed 25-Foot Walk (T25FW) test, and cognitive function using the Paced Auditory Serial Addition Test (PASAT). They also analyzed MRI scans to determine whether either lifestyle habit was associated with new brain lesions.

At enrollment, participants had relatively mild disease, with a median EDSS score of 1.5.

Over six years of follow-up, light smokers were 80% more likely than nonsmokers to reach an EDSS score of at least 3, indicating moderate disability, and 85% more likely to develop walking impairment, defined as taking at least six seconds to complete the T25FW test. Smoking was not significantly associated with a greater likelihood of reaching the PASAT threshold for cognitive impairment.

Disability also worsened more quickly over time in smokers. Light smokers experienced significantly greater increases in EDSS scores after two and six years, while medium smokers showed greater disability worsening after two years. Light smokers also experienced a greater decline in walking speed over time.

Across all these measures, trends toward faster disease progression were also observed for heavy smokers, but the findings failed to reach statistical significance.

Our findings largely corroborate existing evidence that smoking accelerates MS disease progression, reinforcing the clinical imperative to strongly advise all [people with MS] to cease smoking.

The findings for alcohol were less straightforward. Compared with nondrinkers, occasional drinkers were about 50% less likely to reach thresholds for moderate disability, walking impairment, and cognitive impairment during follow-up. Regular drinkers also were less likely to develop walking impairment. However, alcohol consumption was not significantly associated with changes in disability, walking ability, or cognitive function over time.

The researchers, however, cautioned that the apparent benefits of alcohol may reflect reverse causation rather than a protective effect. People with milder disease may be more likely to continue drinking, while those with worsening symptoms may reduce or stop alcohol consumption.

Neither smoking nor alcohol consumption was significantly associated with the development of new brain lesions on MRI scans.

“Our findings largely corroborate existing evidence that smoking accelerates MS disease progression, reinforcing the clinical imperative to strongly advise all [people with MS] to cease smoking,” the researchers concluded. “The role of alcohol remains less certain and a more cautious interpretation of the possibly positive effects is warranted due to the possibility of reverse causality.”