Physical Inactivity, Smoking Linked to Patient Fatigue

People with multiple sclerosis (MS) who smoke tobacco or are not physically active are more likely to experience fatigue that interferes with their daily life, a new study indicates.

The findings suggest that physical exercise and quitting smoking could help ease fatigue in people with MS.

The study, “Associations between fatigue impact and lifestyle factors in people with multiple sclerosis – The Danish MS hospitals rehabilitation study,” was published in the journal Multiple Sclerosis and Related Disorders.

Fatigue — broadly referring to a lack of physical and/or mental energy — affects as many as four out of every five people with MS. It results from a variety of factors, including biological processes related to the disease itself, as well as secondary issues like worse sleep and depression.

Lifestyle factors, from diet to physical activity to substance use, can substantially affect fatigue.

Now, a team of researchers based in Sweden and Denmark looked for connections between reported fatigue and various lifestyle factors.

The team analyzed data from 417 people with MS — median age 51 years, 69% female, and median time of eight years since diagnosis. Of the group, 41% had relapsing-remitting MS, 43% had secondary progressive MS, and 16% had primary progressive MS. All patients were at least somewhat mobile, as evidenced by a score of 7.5 or less on the Expanded Disability Status Scale.

To measure fatigue, the researchers used the Modified Fatigue Impact Scale (MFIS), which assesses how much fatigue affects a person doing common daily activities across three domains — physical, cognitive, and psychosocial. Higher scores on this scale correspond to worse fatigue.

The mean total MFIS score of the group was 39.7 points.

Statistical analysis demonstrated that people with MS who smoked tobacco were more likely to have a higher MFIS score, as well as those who were less physically active. Higher scores were also associated with a shorter time since diagnosis.

Of note, alcohol intake was not significantly associated with MFIS scores in these analyses.

These associations were generally consistent across the three domains, though not all associations were statistically significant for every domain.

“Physical activity showed the most pronounced associations with fatigue impact on physical and psychosocial functioning, while the impact on cognitive functioning showed a trend. Tobacco smoking contributed significantly to impact on psychosocial functioning,” the researchers wrote.

Since physical inactivity and smoking were associated with worse fatigue, the researchers suggested that quitting smoking and exercising more regularly could help people with MS.

“The present study adds further evidence to the beneficial effects of physical activity/exercise for people with MS,” the researchers wrote.

The team noted that further research is needed to determine the optimal exercise regimen for people with MS in terms of reducing fatigue.

“Although future longitudinal studies outlining the optimal physical activity/exercise program are still warranted, introducing physical activity and exercise does seem like a useful approach for rehabilitation services in management of fatigue,” the team wrote.

A notable limitation of the study is that the analyses conducted were designed to find statistical associations, not cause-and-effect relationships. As such, further research is needed to determine whether altering physical activity or smoking status can directly affect fatigue. The researchers also noted that some influences, such as depression and sleep problems, were not included in the analysis.