What happens in ALS, exactly?

What is it?

ALS, also known as Lou Gehrig’s disease and motor neuron disease, is a disease that leads to the death of the neurons that control our voluntary muscles. Typical symptoms of ALS include stiff muscles, muscle twitching, and gradual weakening as the muscles decrease in size. As the disease progresses, patients loose the ability to do things like walk, speak, and swallow, and perhaps the most dangerous consequence is loosing the ability to breathe.

In Europe, ALS affects around 2.2 people per 100 000. Most people with ALS die within 3 to 5 years from onset due to respiratory failure. Around 10% of those affected survive for longer than 10 years.

ALS has gained quite considerable public interest: first because the famous physicist Stephen Hawking  is one of the sufferers, and recently because of the ice bucket challenge that spread on the internet.

What causes it?

About 5-10% of ALS cases can be directly attributed to heredity. People who have close relatives with ALS have a 1% chance of developing the disease. In 90% of cases, however, the cause is not known. Things that have been found to be associated with a higher ALS risk include military service, contact sports, and drug use.

What happens during it?

ALS isn’t seen as a specific disease entity with always the same mechanism: rather, it can be anything that leads to the progressive loss of motor neurons. In ALS, the neurons that are involved in voluntary movement start to die. There are several suggested mechanisms that can cause it.

It is possible, that ALS develops when a protein is misfolded. This misfolded protein could cause the surrounding proteins to misfold, which would start a chain reaction – and eventually, the accumulation of these proteins could kill the neurons.

Another hypothesis is that ALS could be caused by a process called excitotoxicity. Neurons communicate with each other using neurotransmitters. Sometimes, if too many neurotransmitters bind to a neuron, they can cause huge amounts of calcium ions to be released inside it. These calcium ions activate all kinds of enzymes, and this process eventually damages the cell and causes it to die.

How can it be treated?

Unfortunately, there is no cure for ALS. One medication, riluzole, works by decreasing the neuron’s sensitivity to glutamate, and can extend life by a couple of months. Specific symptoms like muscle weakness or stiffness can be relieved through physiotherapy or different medications. During later stages patients need help with breathing and swallowing. It’s a good idea to discuss how and where the patient would like to be treated at an early stage, because later they might not be able to communicate their wishes.



Sources: http://emedicine.medscape.com/article/1170097-overview?pa=Sea59VTCCkIAjrFbpt7ieRkNXArTwBoIb%2B8YuETTt9iMUL15KOB0kemhvzap1wED43mU9jD%2B1DtnxY47OmyybA%3D%3D#a3, http://www.nhs.uk/Conditions/Motor-neurone-disease/Pages/Treatment.aspx, https://en.wikipedia.org/wiki/Amyotrophic_lateral_sclerosis





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