Researchers found that people with multiple sclerosis (MS) who smoke and are obese experienced faster disability progression and increased risk of cognitive impairments. When smoking and obesity were present together, their negative effects were amplified to make the disease progress faster. These findings highlight the importance of making healthy lifestyle choices to help manage MS. Smoking and obesity are modifiable risk factors that can be addressed through healthier lifestyle choices, like eating a well-balanced diet, reducing stress, and being more physically active. The study suggests that addressing even one of these factors could potentially improve health outcomes for people with MS.
Background: Smoking and obesity are both independently linked with higher disease activity and faster progression in MS. Both factors were also reported to work together to raise the risk of other diseases like diabetes and heart disease. Before this study, it was not well understood if smoking and obesity also work together to influence the MS disease course.
Details: Researchers from Karolinska Institute reviewed medical records of more than 3,300 people with MS from the Swedish MS Registry to see how smoking and obesity, individually or together, affect disease progression and cognitive function. Disease progression was characterized based on the Expanded Disability Status Scale (EDSS), which measures disability level by looking at factors like walking, vision, and cognition; MS Impact Scale to measure physical changes; and the Symbol Digit Modalities Test to measure cognitive function.
Results: The study confirmed that smoking and obesity on their own were associated with increased disability progression in people with MS. Smoking, but not obesity, was associated with increased risk of cognitive impairment.
When smoking and obesity were present together, their combined effect on disability progression in MS was much stronger. For example, compared to people with MS who were neither obese nor smokers, the risk of reaching EDSS 4 (a level of disability where people have noticeable difficulties but are still able to walk) was:
- 21% higher in people who smoked but were not obese,
- 33% higher in people who were obese but did not smoke, and
- 86% higher in people who were both obese and smokers.
The interactions between smoking and obesity also amplified the risk of cognitive impairments in people with MS.
Reference:
Article published in: European Journal of Neurology on February 4, 2025 – Smoking and Obesity Interact to Adversely Affect Disease Progression and Cognitive Performance in Multiple Sclerosis.