Amyotrophic Lateral Sclerosis (ALS) Disorder Info

ALS Is a Progressive Neurological Disorder

Stephen Hawking
British physicist Stephen Hawking has ALS. Photo © Getty Images News

Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease, is a disease that attacks the nerve cells (motor neurons) that control muscles. ALS gets worse over time (is progressive). 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 respirator (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 thinking (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 the mind or 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 20% 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 40 and 70, 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.

Symptoms of ALS

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

As yet, there is no cure for ALS. Treatments are designed to relieve the symptoms and improve the quality of life for people with the disorder. Medications can help reduce fatigue, ease muscle cramps, and lessen pain. There is also a specific medication for ALS, called Rilutek (riluzole). It does not repair the damage already done to the body, but it appears to be modestly effective in prolonging the survival of people with ALS.

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

Most people with ALS die from respiratory failure, usually within 3 to 5 years of the diagnosis, but about 10% of people diagnosed with ALS survive for 10 or more years.

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.

"Amyotrophic Lateral Sclerosis Fact Sheet." Disorders A-Z. Apr 2003. National Institute of Neurological Disorders and Stroke. 13 May 2009