Does Exercise Influence Risk of Multiple Sclerosis?

In a prospective analysis of 2 large cohorts of women in the United States, researchers have found that exercise seems unlikely to protect against the risk of multiple sclerosis (MS).¹

While past research has indicated that in patients with MS who have mild or moderate disability, “exercise improves muscular strength and aerobic capacity and may improve mobility, fatigue, and health-related quality of life, … little research has assessed the association of physical activity with the risk of incident MS,”^2,3-5 according to Kassandra L. Munger, ScD, of the Harvard T.H. Chan School of Public Health in Boston, and colleagues.

The researchers prospectively examined the association between exercise in early and adult life and the incidence of MS in women participating in the Nurses’ Health Study (NHS) (n= 81,732; 1986-2004) and the NHS II (n= 111,804; 1989-2009).

Participants reported their physical activity at baseline and in follow-up questionnaires at spans ranging from 2 to 6 years or until the studies’ completions.

While the researchers did find that women who reported higher than average levels of physical activity in adulthood had a lower risk of MS compared with less active women (women in the highest quartile had a 27% reduced rate of MS [RR_pooled= 0.73, 95% CI, 0.55–0.98; p-trend .08] compared with women in the lowest quartile), the trend was not present in 6-year lagged analysis.

This suggests that “lower physical activity could have been an early sign, rather than cause, of MS,” the authors wrote. They also noted that “there was no consistent association of early-life activity with MS.” They also observed a trend of the participants having decreased physical activity at or before the onset of MS.

“Although prior work has shown that physical activity has numerous health benefits, it seems unlikely that it protects against risk of developing MS,” the authors concluded.

While the study does not address whether exercise benefits patients with MS, the authors suggested that physical activity should still be recommended for those with MS due to its benefits to cardiovascular outcomes, “which are a major cause of morbidity and mortality in individuals with MS.”

Regarding limitations, the researchers noted that their study population consisted completely of women and was 95% Caucasian, so results may not be generalizable to other groups.

Disclosures: This study was supported by the US National Institutes of Health (grants T32 HL007575, UM1 CA186107, UM1 CA176726, R01NS046635).

Kirsten S. Dorans reports support from research grants from the National Institutes of Health during the conduct of the study. Dr Chitnishas received personal compensation for advisory board/consulting for Biogen-Idec, Genzyme-Sanofi, and Roche, and has received research support from Merck-Serono and Novartis Pharmaceuticals. Dr Ascherio reports research grants from the National Institutes of Health, the National Multiple Sclerosis Society, and the Department of Defense and has served on a medical advisory board for Bayer HealthCare. Kassandra L. Munger has received a research grant from the National Multiple Sclerosis Society. See the study for full disclosures.

References

1. Dorans KS, Massa J, Chitnis T, Ascherio A, Munger KL. Physical activity and the incidence of multiple sclerosis. Neurology. 2016; doi:10.1212/WNL.0000000000003260. [Epub ahead of print]
2. Latimer-Cheung AE, Pilutti LA, Hicks AL, et al. Effects of exercise training on fitness, mobility, fatigue, and health related quality of life among adults with multiple sclerosis: a systematic review to inform guideline development. Arch Phys Med Rehabil. 2013;94:1800–1828.
3. Warren SA, Warren KG, Greenhill S, Paterson M. How multiple sclerosis is related to animal illness, stress and diabetes. Can Med Assoc J. 1982;126:377.
4. Ghadirian P, Dadgostar B, Azani R, Maisonneuve P. A case-control study of the association between sociodemographic, lifestyle and medical history factors and multiple sclerosis. Can J Public Health. 2001;92:281–285.
5. AlterMAA, Leibowitz U. Epidemiology of multiple sclerosis in Israel. In: Alter MK, ed. The Epidemiology of Multiple Sclerosis. Springfield, IL: CC Thomas; 1968:83–109.