‘Do what we can, summer will have its flies.’ ~ Ralph Waldo Emerson
Summer is traditionally a time to let your hair down, kick off your shoes and smell the flowers, but for people with multiple sclerosis (MS), the season’s higher temperatures can cause symptoms to flare.
Warmer weather, especially when it’s humid, tends to temporarily worsen MS neurological symptoms but does not cause the disease to progress, according to the National Multiple Sclerosis Foundation.
For example, some people’s vision becomes blurred when they get overheated — a phenomenon known as Uhthoff's sign. These temporary changes can result from even a very slight elevation in core body temperature (.25 to .5 of a degree) because an elevated temperature further impairs the ability of a demyelinated nerve to conduct electrical impulses, according to the MS Society.
Some people with MS may also experience more difficultly in performing mental tasks — such as following instructions, learning new information or recalling information from memory — when the weather is hot.
Scientists at the Kessler Foundation Research Center in West Orange, N.J., examined a possible link between outside temperature and the ability of people with MS to perform various mental tasks.
The researchers tested the cognitive skills of 40 people with MS and compared them with 40 people without the disease. The researchers also recorded the average outside temperature on the testing days.
The results, published early online in the March 7, 2012 edition of the journal Neurology, showed people with MS tended to perform worse when the weather was hotter. People without MS performed equally as well regardless of the outside temperature.
Although the results need further exploration, the researchers say the results are important clues for designing future clinical trials and interpreting the results. This study also confirmed previous studies suggesting people with MS should take temperature into consideration when making lifestyle decisions, such as taking a mentally-challenging college course during summer.