What Is Amyotrophic Lateral Sclerosis (ALS)?

A progressive neurological disorder also called Lou Gehrig's disease

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Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease, is a disease that attacks the nerve cells (motor neurons) that control muscles. ALS is progressive disease, meaning it gets worse over time. Motor neurons carry messages about movement from the brain to the muscles, but in ALS the motor neurons degenerate and die; therefore, the messages no longer get to the muscles. When muscles aren't used for a long time, they weaken, waste away (atrophy), and twitch under the skin (fasciculate).

Eventually, all the muscles that a person can control (voluntary muscles) are affected. People with ALS lose the ability to move their arms, legs, mouth, and body. It may get to the point that the muscles used for breathing are affected and the person might need a ventilator in order to breathe.

For a long time it was believed that ALS only affected muscles. It is now known that some individuals with ALS experience changes in cognition, such as problems with memory and decision-making. The disease can also cause changes in personality and behavior, such as depression. ALS does not affect intelligence, or the ability to see or hear.

What Causes ALS?

The exact cause of ALS is not known. In 1991, researchers identified a link between ALS and chromosome 21. Two years later, a gene that controls the enzyme SOD1 was identified as being associated with about 10% of the inherited cases in families.

SOD1 breaks down free radicals, harmful particles that attack cells from the inside and cause their death. Since not all inherited cases are connected to this gene, and some people are the only ones in their families with ALS, other genetic causes may exist.

Who Gets ALS?

People are most commonly diagnosed with ALS between the ages of 55 and 75, but younger people can also develop it. ALS affects people all over the world and of all ethnic backgrounds. Men are affected more often than women.

About 90% to 95% of ALS cases appear randomly, meaning no one in the person's family has the disorder. In about 5% to 10% of cases, a family member also has the disorder. Military veterans are at higher risk for ALS, but the reason for this is not clear.

Symptoms of ALS

Usually ALS comes on slowly, starting out as weakness in one or more muscles. Only one leg or arm may initially be affected.

Other symptoms include:

  • Twitching, cramping, or stiffness of muscles
  • Stumbling, tripping, or difficulty walking
  • Difficulty lifting things
  • Difficulty using the hands

As the disease progresses, the person with ALS will not be able to stand or walk; they will have trouble moving around, talking, and swallowing.

Diagnosis of ALS

The diagnosis of ALS is based on the symptoms and signs the doctor observes, as well as test results that eliminate all the other possibilities, such as multiple sclerosis, post-polio syndrome, spinal muscular atrophy, or certain infectious diseases.

Usually the testing is performed and the diagnosis is made by a doctor who specializes in the nervous system (a neurologist).

ALS Treatment

ways to improve life expectancy with Lou Gehrig's Disease
Verywell / Melissa Ling

As of yet, there is no cure for ALS. Treatments are designed to relieve the symptoms and improve the quality of life for people with the disease.

Medications can help reduce fatigue, ease muscle cramps, and lessen pain. There are three specific medications for ALS:

  • Radicava (edaravone)
  • Rilutek (riluzole)
  • Relyvrio (sodium phenylbutyrate/ taurursodiol)

These do not repair the damage already done to the body, but they appear to be modestly effective in prolonging the survival of people with ALS.

Through physical therapy, the use of special equipment, and speech therapy, people with ALS can remain mobile and able to communicate for as long as possible.

While the average survival time after being diagnosed with ALS is three years, about 20% of people with ALS live five years; 10% will survive 10 years and 5% will live 20 years or longer. Most people with ALS die from respiratory failure.

Future Research

Researchers are examining many possible causes for ALS, such as the autoimmune response (in which the body attacks it own cells) and environmental causes, such as exposure to toxic or infectious substances.

Scientists have found that people with ALS have higher levels of the chemical glutamate in their bodies, so research is looking at the connection between glutamate and ALS.

In addition, scientists are looking for some biochemical abnormality that all people with ALS share so that tests to detect and diagnose the disorder can be developed.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Neurological Disorders and Stroke. Amyotrophic Lateral Sclerosis (ALS) fact sheet.

  2. Siddique T, Figlewicz DA, Pericak-Vance MA, et al. Linkage of a gene causing familial amyotrophic lateral sclerosis to chromosome 21 and evidence of genetic-locus heterogeneity. N Engl J Med. 1991 May 16;324(20):1381-4. doi:10.1056/NEJM199105163242001

  3. Rosen D, Siddique T, Patterson D, et al. Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosisNature 362 59–62 (1993). doi:10.1038/362059a0

  4. ALS Association. Symptoms and Diagnosis.

  5. ALS Association. FDA-approved drugs.

  6. ALS Association. Stages of ALS.

  7. Turner MR, Goldacre R, Ramagopalan S, Talbot K, Goldacre MJ. Autoimmune disease preceding amyotrophic lateral sclerosis: an epidemiologic studyNeurology. 2013;81(14):1222-1225. doi:10.1212/WNL.0b013e3182a6cc13

  8. ALS Association. Glutamate.

Additional Reading

By Mary Kugler, RN
Mary Kugler, RN, is a pediatric nurse whose specialty is caring for children with long-term or severe medical problems.