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Multiple Sclerosis Health Center

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Warmer Weather & Brain Function in People With MS

MRI study found that some brains respond abnormally to higher temperatures


The good news, LaRocca said, is that when people with MS have to do thinking tasks in the presence of heat, their brain is recruiting more areas of the brain to accomplish what it needs to do. The bad news, he said, is that the brain is working in a different way than someone who doesn't have MS, so it's functioning abnormally.

Although why this happens remains unclear, LaRocca said the fact that MS compromises the central nervous system could play a role. "Physically, the ability of the nervous system to transmit impulses from one part to another has been compromised because of damage to the nerve fibers," he said.

In order to transmit electrical impulses, the body has a complex system of chemical interactions, LaRocca said. Over the course of evolution, these interactions developed in such a way that they work best within a narrow temperature range, he said. Even slight temperature changes can interfere with that natural process.

"For those with MS, the transmission of nerve impulses is already compromised, so in a sense it may not take as much to push it over the line into dysfunction," LaRocca said.

So exactly how high do temperatures need to rise before it affects brain function in people with MS? Study author Leavitt said that's another question that remains unanswered.

"Although everyone is interested in a critical cutoff point when it becomes too hot, this cross-sectional study doesn't look at how rising temperatures affect individuals, or when hot becomes too hot," she said.

Since MS is a complicated disorder that varies from person to person, there is likely no simple answer, LaRocca said. "Some people are heat sensitive, while others can tolerate it better," he said.

For people with MS who experience a worsening of symptoms when temperatures rise, LaRocca recommended some cooling strategies:

  • Wear cooling hats or garments, such as vests with gel packs inserted into them.
  • Cool the body before exercise.
  • Use air conditioning.

Although it has not been proven, LaRocca said high humidity also could be a factor since it makes it harder for the body to compensate for high temperatures.

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