Smoking, Drinking Tied to Increased MS Risk, More Severe Symptoms

Megan Brooks

March 10, 2022

High alcohol consumption may contribute to more severe neurodegeneration in patients with multiple sclerosis (MS) — and smoking may make a diagnosis of MS more likely, new research suggests.

"Our results add to the understanding of how health-associated behaviors, such as alcohol consumption and smoking, interact with neurodegeneration in MS," lead author Iris Kleerekooper, MD, clinical research fellow, Queen Square Multiple Sclerosis Center, Institute of Neurology, University College London, United Kingdom, told Medscape Medical News.

Of note, patients with MS who drank alcohol daily or almost daily had thinner retinal thicknesses, indicative of more brain atrophy, compared with those who drank less.

"This indicates that health advice that holds for the general population — don't smoke and consume alcohol in no more than moderate quantities — may hold extra relevance for people with MS," Kleerekooper said.

The study results were published online March 3 in JAMA Network Open.

Key Findings

Using the UK Biobank study, the researchers investigated associations of alcohol consumption and smoking with MS diagnosis and retinal thickness in 71,981 individuals aged 40 to 69 years. Of these participants, 179 had MS.

Among the key findings, smoking was associated with a threefold increased risk of receiving an MS diagnosis (odds ratio [OR], 3.05; 95% CI, 1.95 – 4.64).

In addition, daily or almost daily alcohol intake was associated with a thinner macular ganglion cell layer and inner plexiform layer (mGCIPL) in patients with MS (adjusted β = −3.09; 95% CI, −5.70 to −0.48 μm; P = .02).

Participants who said they drank daily or almost daily had almost 5% thinner mGCIPLs, a substantial difference in retinal thickness, the investigators note.

Paradoxically, moderate alcohol intake, defined as consuming alcohol once per month up to 4 times per week, was associated with lower odds of an MS diagnosis.

The investigators note that a protective effect of moderate alcohol consumption on MS risk has previously been reported, although an increased risk has also been reported.

"Owing to the cross-sectional nature of the present study, the 'sick quitters' effect' — that is, the tendency to quit or profoundly limit alcohol intake when ill, could have influenced our findings," they write.

Toxic Brew

Commenting for Medscape Medical News, Eoin Flanagan, MBBCh, neurologist, Mayo Clinic, Rochester, Minnesota, said the study "highlights the detrimental effect" of cigarette smoking and consuming high amounts of alcohol.

It also "confirms the findings from many previous studies showing that smoking increases the risk of developing MS, and we also know that cigarette smoking makes MS worse," said Flanagan, who was not involved with the current research.

"This gives us another reason to avoid cigarette smoking, particularly in those who already have MS," he added.

The study also indicates that "high quantities of alcohol are toxic to the retina, and that may be particularly detrimental in patients with MS, in which optic nerve and retinal damage is common from the disease itself," he noted.

"I think the take-home message for providers is that patients with MS should avoid high quantities of alcohol and cigarette smoking. Thus, public health measures that target reducing cigarette smoking could be particularly effective in helping prevent MS," Flanagan concluded.

The study was funded by the postdoctoral research fellowship exchange program from the European Committee for Treatment and Research in Multiple Sclerosis and by the University College London Hospital Biomedical Research Centre. Kleerekooper and Flanagan have reported no relevant financial relationships.

JAMA Netw Open. Published online March 3, 2022. Full article

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