What is ALS?

Amyotrophic lateral sclerosis (ALS) is an adult-onset disease that usually begins between the ages of 40 and 70. Men and women of all ethnic and racial groups are generally affected equally, but the cause is unknown.

There is no single diagnostic test for ALS, and as a result, the diagnosis is often delayed. Several tests must be conducted to exclude the possibility of other similar, but treatable, diseases.

ALS: what it is and what the name really means
ALS is a rapidly progressing neurological disorder in which most motor neurons in the spinal cord and brain degenerate, typically over three to five years. When the motor nerve cells degenerate, many types of voluntary movement are impaired and ultimately lost.

The name amyotrophic lateral sclerosis is Greek in origin. A means "no" or "negative," myo refers to muscle, and trophic stands for nourishment. So, amyotrophic means "no muscle nourishment." Lateral sclerosis refers to the fact that the sides of the spinal cord appear scarred, or sclerosed, in late-stage ALS.

ALS: the initial onset and symptoms
Initially, symptoms of ALS may include isolated muscle weakness, muscle twitching, cramping and stiffness of muscles, unusual fatigue and clumsiness, or difficulty swallowing and speaking.

Although the sequence of emerging symptoms and the progression rate for the disease differ from person to person, most muscle in a person with ALS will ultimately weaken and become paralyzed.

Many functions other than movement are spared in ALS. For example, a patient's thinking ability, bladder and bowel function, sexual function, sight, hearing, smell, taste and touch are unaffected. When the muscles in the diaphragm and chest wall fail, patients cannot breathe and most will die from respiratory failure, usually three to five years after the symptoms begin. Fortunately, there are excellent respiratory support systems to forestall this problem.

ALS: the real cause remains a mystery
The cause of most cases of ALS is unknown. About 10% of cases run in families, and in some of these cases there are defined genetic defects that are known to trigger the disease. For example, some familial cases arise because of mutations in a gene that makes a free radical absorbing protein, known as superoxide dismutase (SOD1). Other cases arise because of mutations in genes (called FUS/TLS and TDP43) that make proteins that bind to a genetic material in cells known as RNA.

Another gene implicated in familial ALS makes a protein called angiogenin. The causes of non-familial ALS are not defined. We do know that in both familial and non-familial ALS, several factors seem to play a role in motor neuron degeneration, including high levels of the neurotransmitter glutamate, exposure to adverse environmental factors such as infections or poisons, insufficient energy generation by brain cells, inflammation in the spinal cord, and slowing of the transport of substances in long neuron processes known as axons.

ALS: new treatments are being developed
There is no cure for ALS. A single drug called riluzole is approved for use in ALS, but at best it modestly slows the disease. ALS Therapy Alliance researchers are dedicated to discovering new treatments for ALS. Several experimental drugs are in trials and in development in ALS research laboratories.

Though they are not ALS specific, and there are no therapies that slow the basic process of degeneration of motor nerves, other treatments, such as feeding and breathing aids, relieve some of the symptoms of ALS. In addition, some drugs are helpful for problems like fatigue, muscle cramps, depression and sleep disturbance.

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The Faces of ALS