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Multiple Sclerosis Activity Highest in Warm Weather Months


Researchers from Brigham and Women’s Hospital have found a link between environmental factors occurring in spring and summer, such as increased temperature and solar activity, have a negative effect on multiple sclerosis symptoms, leading to increased disease activity.

MS Disease Activity Highest in Spring and Summer

Multiple sclerosis, or MS, is a debilitating disease in which the body’s immune system destroys the protective sheath that covers the nerves interfering with communication and resulting in deterioration of the tissue. Symptoms of MS include numbness or weakness in one or more limbs, partial or complete loss of vision, tremor, tingling or pain, fatigue, and dizziness.

Women are more likely to develop MS, and diagnosis usually occurs between the ages of 20 and 40.

Read: Smoking Increases Chances of Multiple Sclerosis in Those with Epstein-Barr Virus

The study led by Dr. Dominik Meier and published in the August 31st issue of Neurology, used data taken between 1991 and 1993 from 44 people aged 25 to 52 with untreated multiple sclerosis. The participants underwent an average of 22 MRI brain scans each during the two year period. MRI scans use a magnetic field and radio waves to reveal brain and spinal cord lesions, indicative of the myelin sheath loss caused by MS.

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They also tracked weather data including daily temperature, solar radiation and rainfall.

“Our results showed that the appearance of lesions on brain scans was two to three times higher in the months of March to August, compared to other months of the year,” Meier said. Extreme heat is known to cause extreme muscle weakness and worsening of MS symptoms, but this study is the first to compare brain lesions to weather changes.

According to the National Multiple Sclerosis Society (NMSS), about 400,000 people in the United States have MS.

Read: Vitamin D Deficiency in MS

Neurologist Anne Cross, of the Washington University School of Medicine in St. Louis, wrote an accompanying editorial for the journal. She recommends that patients be careful about extreme heat, and stay indoors in air-conditioning during the hottest part of the day. Exercise can offer benefits to patients with MS by improving strength, balance and coordination – swimming is a good option to avoid heat-related symptom exacerbation.

Source Reference:
"Seasonal prevalence of MS disease activity."
D.S. Meier, K.E. Balashov, B. Healy, H.L. Weiner, and C.R.G. Guttmann.
Neurology, 31 August 2010, Volume 75, Issue 9, pp 799-806.



Is the prevalence of MS higher in warmer climates compared to cooler? What about between countries north and south of the equator - are there seasonal differences as well?