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Updated on October 10, 2024
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that primarily affects nerve cells called motor neurons. Motor neurons allow the nervous system to communicate with muscles. Anytime a person performs a voluntary muscle movement—walk, talk, chew food, sign their name—motor neurons are firing. They’re also responsible for breathing.
Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The motor neurons located in the brain are called upper motor neurons. The motor neurons located in the spine are called lower motor neurons. ALS can affect both.
ALS destroys motor neurons. As a result, the brain is no longer able to initiate or control voluntary muscle movements. A person loses the ability to use their muscles and as a result, the muscles atrophy, or waste away. The person may also develop difficulty breathing, which may lead to death.
Almost 30,000 people in the U.S. are living with the disease as of 2018, the last date for which accurate data is available.
Here are some other key facts about ALS.
Fact 1: It’s also known as Lou Gehrig's Disease.
ALS is also commonly known as Lou Gehrig's Disease, named in 1939 after the famed baseball player Lou Gehrig, who was diagnosed with the condition on his 36th birthday.
However, the first cases of the disease were described in 1869 by French neurologist Jean-Martin Charcot.
Fact 2: Early symptoms can be subtle.
Early signs and symptoms can be subtle. A person may experience muscle cramps or stiffness, may be clumsy or trip when walking, or their muscles may feel more fatigued than usual. Early symptoms may also include:
- Muscle twitches
- Muscle weakness in the neck, arm, or leg
- Slurred speech
- Nasal-sounding speech
- Trouble chewing or swallowing food
These signs and symptoms can easily be overlooked or dismissed, and may not seem significant until more severe signs and symptoms emerge.
Over time, new symptoms may develop in addition to those already listed, including:
- Drooling
- Trouble forming words
- Difficulty breathing
- Constipation
- Unexpected weight loss
- Crying or laughing without meaning to
At this point, symptoms begin to become less subtle, more serious, and hard to ignore.
Fact 3: Most cases develop at random.
ALS is a very rare disease, and there are two main types: sporadic and familial. Sporadic means the disease developed randomly in a person who had no risk factors and who didn’t have a family history of ALS. Almost all cases of ALS are sporadic. A small percentage, about 10 percent, of ALS cases are due to inherited genes. However, even if you have a family member with ALS, your risk is still low.
Statistically, some groups seem to be at higher risk of ALS than others, including people aged between 55 and 75, as well as white and non-Hispanic people. In younger age groups, people assigned male at birth develop ALS a bit more often than people assigned female at birth, but the risk evens out in older age groups.
Finally, there is some limited evidence for military veterans being at higher risk for ALS. Researchers don’t yet understand the reasons why, but they’ve speculated it might be due to head injuries or exposure to environmental chemicals.
Fact 4: Diagnosis can be challenging.
The symptoms of ALS overlap with other neurological conditions, and there is no single test to diagnose ALS. This can make diagnosis a challenge, and the process involves ruling out other conditions that can cause symptoms. A number of tests may be ordered, including:
- Electromyography (EMG), which looks at how the muscles and nerves are working. This test can involve a nerve conduction study (NCS), which measures how well a nerve is able to send a signal along its length. It can also include a needle exam, which uses a needle electrode to measure the electrical activity in the fibers of the muscles.
- Spinal tap, also known as a lumbar puncture, which uses a needle to collect some of the fluid that surrounds the spinal cord and brain so it can be tested.
- Myelogram of the cervical spine, which takes pictures of the spine in the neck after injection of a dye, which helps show issues that aren’t visible with a regular X-ray.
- Magnetic resonance imaging (MRI), which uses a magnetic field to look at pictures of the brain and spinal cord.
- Blood and urine tests
- Muscle and/or nerve biopsy
- Thorough neurological examination
In the early stages of the disease, people with ALS may need assistance from others or assistive devices to carry out daily tasks. People in the advanced stages of ALS will no longer be able to walk, stand, use their hands, or even breathe without assistance. They may also experience anxiety and depression because the disease doesn’t usually affect their cognitive abilities, or the ability to think. So people with ALS are aware of their situation and their limitations.
ALS is a terminal illness, and usually people pass away about three to five years after they first start experiencing symptoms. About one out of every 10 people with ALS may live for 10 years or more. Researchers aren’t clear about why certain people live longer, but being diagnosed at an early age seems to help. Famously, physicist Stephen Hawking lived for more than 50 years after diagnosis; he was diagnosed at the unusually young age of 21.
Fact 5: ALS is associated with a type of dementia.
Usually, ALS does not affect the parts of the brain associated with cognition—a person’s ability to think, remember, and reason. However, sometimes ALS may be associated with a type of dementia called frontotemporal dementia.
Dementia is a general term that describes the loss of cognitive ability. There are many different types of dementia. Frontotemporal dementia is a group of dementias that affect the frontal and temporal lobes of the brain.
Symptoms associated with frontotemporal dementia include changes in personality (such as inappropriate behavior), impaired judgement, trouble regulating emotions, and problems with both using and understanding language.
ALS is increasingly being recognized as not only a disease that affects motor neurons, but a multisystem disorder that can sometimes affect several areas of the central nervous system, including the brain.
Research is looking for new treatments
Right now, there is no cure for ALS. Because it’s a disease that affects so many systems in the body and so many aspects of a person’s life, the best way to support someone with ALS is with a team of healthcare providers, including physicians, nutritionists, social workers, physical and occupational therapists, psychologists, speech and respiratory therapists, and hospice and home care nurses.
Only a few medications are available that can treat ALS. These treatments don’t stop the disease from progressing, but they can sometimes slow it down and raise a person’s quality of life. Treatments may be most helpful if a person manages to get a diagnosis in the early stages of the disease.
As of 2024, there are three drugs that have been approved by the U.S. Food and Drug Administration (FDA) and are considered effective for specifically treating ALS:
- Riluzole (Rilutek): a liquid or tablet medication that may lower the amount of damage to the motor neurons and extend survival by several months.
- Edaravone (Radicava): an oral or intravenous (IV) medication that may slow down the rate at which ALS affects a person’s ability to function in daily life.
- Tofersen (Qalsody): a medication given by injection into the spine, which may lower damage to neurons in people with ALS who have a specific gene mutation.
Many other drugs, treatments, and therapies are often incorporated into a care plan to help manage symptoms, but they won’t treat the cause of the disease itself. This includes anything from pain medications to antidepressants to tracheostomies, which are surgically designed alternative airways through which a breathing tube is placed.
More research must be done to understand exactly how the disease works. In 2023, the National Institute of Neurological Disorders and Stroke (NINDS), which is part of the National Institutes of Health (NIH), published a set of strategic research priorities. These are helping to guide ALS researchers around the world who are working hard to find effective ways to prevent, diagnose, treat, and cure ALS.
