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SciShow News explains the science behind ALS, the disease that has inspired millions to take the Ice Bucket Challenge. Learn what ALS is, what we do and don’t know about it, and watch SSN hosts take the challenge themselves!

Hosted by: Reid Reimers

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Sometimes the internet can make us do stupid things, like stay up until three in the morning watching videos of kittens stuck inside hamster balls. Or make us think that swallowing a tablespoon of cinnamon is suddenly a good idea. It isn't; don't do it.  But by now you've heard about the ice bucket challenge, and it's proving to be a rare instance of the internet spurring people to do something that's actually worthwhile. The challenge itself, as I'm sure you know, is just a way to publicly pledge support for research into a disease known as ALS, and get others to do the same. Which raises the question of what ALS is and how we think we can beat it.

Amyotrophic Lateral Sclerosis is the most common type pf motor neuron disease--a condition of the nervous system that targets the motor neurons, those nerve cells in your brain, brain stem, and spinal cord that communicate directly with your muscles to make all of your voluntary movements possible. ALS causes these neurons to degrade, making them unable to send signals to the muscle fibers that make movement possible. It begins very subtly, sometimes with symptoms like being unable to speak clearly, or having trouble chewing, or experiencing what feel like muscle cramps. But as the disease progresses, more neurons degrade and more muscles stop receiving stimuli, which causes them to weaken and atrophy or lose muscle tissue. Ultimately, in the later stages in the disease, patients can become paralyzed, and the neuron degeneration can move onto those nerve calls that affect involuntary actions, namely breathing. Most patients die within two to five years of diagnosis.

ALS is one of the few diseases that can be legitimately described as mysterious because even though 140,000 people in the world are diagnosed with some sort of motor neuron disease each year--that's 384 new cases a day--we still don't have a clear idea about what causes them. Between five and ten percent of ALS cases seem to have genetic origins, for example. Researchers in the past few years have identified dozens of genetic mutations that show up in some ALS patients, like defects that corrupt the enzymes that help protect our cells from toxins. But it's not clear how most of these mutations specifically affect motor neurons, and other cases seem to suggest that environmental factors can also play a role. According to the US National Institutes of Health, for instance, military personnel who served in the Persian Gulf region during the 1991 war were more likely to develop ALS than those who didn't serve there. So it may turn out that ALS is more like a syndrome that has many different causes, and perhaps the genetic clues that we're seeing simply put those people at greater risk. We're just at the very beginning of understanding ALS, and since we don't have a handle on what causes it, there's also no cure. There is one drug available in the US that seems to slow the progression of the disease in some patients, but most of the other treatments are focused on simply alleviating the symptoms that come from losing muscle control and improving the quality of life for patients as much as possible.

Now, there are a lot of diseases that are worth taking an icy bath to help fight, and this is definitely one of them.

Caitlin: Aaahhh, hahaha!

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