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What Is ALS (Amyotrophic Lateral Sclerosis)?

Amyotrophic lateral sclerosis (ALS) is a rare group of neurological diseases. These diseases mainly involve the nerve cells (neurons) that are responsible for controlling voluntary muscle movement. Voluntary muscles produce movements like:

  • chewing,
  • walking,
  • breathing, and
  • talking.

The disease is progressive, meaning the symptoms get worse over time. Currently, there is no cure for ALS and no effective treatment to halt, or reverse, the progression of the disease.

ALS belongs to a wider group of disorders known as motor neuron diseases. The gradual deterioration (degeneration) and death of motor neurons causes these diseases.

Motor neurons are nerve cells that extend from the brain to the spinal cord. They also extend to muscles throughout the body. These motor neurons provide communication links between the brain and the voluntary muscles.

Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord and to motor nuclei of brain (called lower motor neurons). They they move from the spinal cord and motor nuclei of brain to a particular muscle or muscles.

In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, and stop sending messages to the muscles. Unable to function, the muscles gradually weaken, start to twitch (called fasciculations), and waste away (atrophy). Eventually, the brain loses its ability to initiate and control voluntary movements.

Early Signs of ALS

Early symptoms of ALS usually include muscle weakness or stiffness. Gradually all muscles under voluntary control are affected. If you have ALS, you lose your strength and the ability to speak, eat, move, and even breath.

Why Choose University of Utah Health?

Our multidisciplinary team of specialists in the Motor Neuron Disease/ALS Clinic specializes in caring for people with ALS and understands the challenges of an ALS diagnosis. They see patients at the Clinical Neurosciences Center in Salt Lake City.

We are here to help you take control of your health and support you every step of the way. The Motor Neuron Disease/ALS Clinic is recognized as a Certified Center of Excellence by the ALS Association.

Group shot of ALS providers and staff sitting and standing in front of the U of U Health logo projected onto a screen

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Who Gets ALS?

ALS is a common neuromuscular disease worldwide. It affects people of all races and ethnic backgrounds. There are several potential risk factors for ALS including:

  • Age. Although the disease can strike at any age, symptoms most commonly develop between the ages of 55 and 75.
  • Gender. Men are slightly more likely than women to develop ALS. However, as age the difference between men and women disappears.
  • Race and ethnicity. Most likely to develop the disease are Caucasians and non-Hispanics.

Some studies suggest that military veterans are more likely to develop ALS. Although the reason for this is unclear, possible risk factors for veterans include exposure to lead, pesticides, and other environmental toxins. ALS is recognized as a service-connected disease by the U.S. Department of Veterans Affairs.

Sporadic ALS

The majority of ALS cases (90 percent or more) are considered sporadic. This means the disease seems to occur at random with no clearly associated risk factors and no family history of the disease.

Although family members of people with sporadic ALS are at an increased risk for the disease, the overall risk is very low and most will not develop ALS.

Familial (Genetic) ALS

About five to 10 percent of all ALS cases are familial, which means that an individual inherits the disease from his or her parents. The familial form of ALS usually only requires one parent to carry the gene responsible for the disease.

Mutations in more than a dozen genes have been found to cause familial ALS. About 25 to 40 percent of all familial cases (and a small percentage of sporadic cases) are caused by a defect in a gene known as “chromosome 9 open reading frame 72,” or C9ORF72.

Interestingly, the same mutation can be associated with atrophy of frontal-temporal lobes of the brain causing frontal-temporal lobe dementia. Some individuals carrying this mutation may show signs of both motor neuron and dementia symptoms (ALS-FTD).

Another 12 to 20 percent of familial cases result from mutations in the gene that provides instructions for the production of the enzyme copper-zinc superoxide dismutase 1 ( SOD1).

ALS Symptoms

ALS can be so subtle that you may not notice the first symptoms. Gradually, however, these symptoms develop into more obvious weakness or atrophy that may cause a physician to suspect ALS. Some of the early symptoms include:

  • muscle twitches in the arm, leg, shoulder, or tongue;
  • muscle cramps;
  • tight and stiff muscles (spasticity);
  • muscle weakness affecting an arm, a leg, neck or diaphragm;
  • slurred and nasal speech; and
  • difficulty chewing or swallowing.

For many individuals the first sign of ALS may appear in the hand or arm as you try to do simple tasks, such as buttoning a shirt, writing, or turning a key in a lock.

In other cases, your symptoms may affect one of your legs. You may experience awkwardness when walking or running or you may notice that you are tripping or stumbling more often.

Limb Onset ALS & Bulbar Onset ALS

When symptoms begin in the arms or legs, it is referred to as limb onset ALS.  Other individuals first notice speech or swallowing problems, which is called bulbar onset ALS.

Regardless of where the symptoms first appear, muscle weakness and atrophy spread to other parts of the body as the disease progresses. Individuals may develop problems with:

  • moving,
  • swallowing (dysphagia),
  • speaking or forming words (dysarthria), and
  • breathing (dyspnea).  

The order that the symptoms begin to show and the rate the disease progresses are different from person to person. Eventually, however, you will not be able to stand or walk, get in or out of bed on your own, or use your hands and arms.

Individuals with ALS usually have difficulty swallowing and chewing food, which makes it hard to eat normally and increases the risk of choking. They also burn calories at a faster rate than most people without ALS. Due to these factors, people with ALS tend to lose weight rapidly and can become malnourished.

Because people with ALS usually retain their reasoning, remembering, understanding, and problem solving capabilities, they are aware of their progressive loss of function. This can cause anxiety and depression.

A small percentage of individuals may experience problems with language or decision-making. There is growing evidence that some may even develop a form of dementia over time.

Individuals with ALS will have difficulty breathing as the muscles of the respiratory system weaken. They eventually lose the ability to breathe on their own and must depend on a ventilator.

If you have ALS, your chances of getting pneumonia during later stages of the disease are also higher. Besides muscle cramps that may cause discomfort, you may develop painful neuropathy (nerve disease or damage) as well.

How Is ALS Diagnosed?

No one test can provide a definitive diagnosis of ALS. Physicians primarily diagnose it from a detailed history of the symptoms and signs they see during physical examination. They also do a series of tests to rule out other mimicking diseases. However, the presence of upper and lower motor neuron symptoms strongly suggests the presence of the disease.

Physicians will review your full medical history and conduct a neurologic examination at regular intervals. This examination assesses whether symptoms are getting worse.

ALS symptoms in the early stages of the disease can be similar to those of a wide variety of other, more treatable diseases or disorders. Your physician will rule out other conditions by having you take different tests.

Muscle & Imaging Tests

Electromyography (EMG) is a special recording technique that detects electrical activity of muscle fibers. EMG can help diagnose ALS. Another common test is a nerve conduction study (NCS). This measures electrical activity of the nerves and muscles by assessing the nerve’s ability to send a signal along the nerve or to the muscle.

If your provider sees abnormalities in the NCS and EMG, they can tell whether you have a form of peripheral neuropathy (damage to peripheral nerves outside of the brain and spinal cord) or myopathy (muscle disease) rather than ALS.

A physician may also order a magnetic resonance imaging (MRI) test. A MRI is a noninvasive procedure that uses a magnetic field and radio waves to produce detailed images of the brain and spinal cord.

Standard MRI scans are generally normal in people with ALS. However, they can reveal other problems that may be causing the symptoms, such as a spinal cord tumor, a herniated disk in the neck that compresses the spinal cord, syringomyelia (a cyst in the spinal cord), or cervical spondylosis (abnormal wear affecting the spine in the neck).

Laboratory Tests

Based on the your symptoms, test results, and findings from the examination, a physician may order other tests. These could include blood and urine samples that would help eliminate the possibility of other diseases.

Tests for Other Diseases & Disorders

Infectious diseases such as human immunodeficiency virus (HIV), human T-cell leukemia virus (HTLV), polio, and West Nile virus can, in some cases, cause ALS-like symptoms.

Neurological disorders, such as multiple sclerosis, post-polio syndrome, multifocal motor neuropathy, and spinal and bulbar muscular atrophy (Kennedy’s disease), also can mimic certain features of the disease. Fasciculations and muscle cramps also occur in benign conditions.

Because there are many related conditions that are appear like ALS in the early stages of the disease, you may want to get a second opinion from a neurologist.

What Causes ALS?

The cause of ALS is not known, and scientists do not yet know why ALS strikes some people and not others. However, evidence from scientific studies suggests that both genetics and environment play a role in the development of ALS.

Is ALS Genetic?

An important step toward determining ALS risk factors was made in 1993 when scientists supported by the National Institute of Neurological Disorders and Stroke (NINDS) discovered that mutations in the SOD1 gene were associated with some cases of familial ALS.

Although it is still not clear how mutations in the SOD1 gene lead to motor neuron degeneration, there is increasing evidence that the gene playing a role in producing mutant SOD1 protein can become toxic.

Since then, scientists have identified more than a dozen additional genetic mutations. Many have been identified through NINDS-supported research. Each of these gene discoveries is providing new insights into possible mechanisms of ALS.

The discovery of certain genetic mutations involved in ALS suggests that changes in the processing of RNA molecules may lead to ALS-related motor neuron degeneration. RNA molecules are one of the major macromolecules in the cell involved in directing the synthesis of specific proteins as well as gene regulation and activity.

Other gene mutations indicate defects in the natural process in which malfunctioning proteins are broken down and used to build new ones, known as protein recycling. Still others point to possible defects in the structure and shape of motor neurons, as well as increased susceptibility to environmental toxins.

Overall, it is becoming increasingly clear that a number of cellular defects can lead to motor neuron degeneration in ALS.

In 2011 another important discovery was made when scientists found that a defect in the C9ORF72 gene is not only present in a significant subset of individuals with ALS but also in some people with a type of frontotemporal dementia (FTD). This observation provides evidence for genetic ties between these two neurodegenerative disorders.

Most researchers now believe ALS and some forms of FTD are related disorders.

Environmental Factors

In searching for the cause of ALS, researchers are also studying the impact of environmental factors. Researchers are investigating a number of possible causes, such as:

  • exposure to toxic or infectious agents,
  • viruses,
  • physical trauma,
  • diet, and
  • behavioral and occupational factors.

For example, researchers have suggested that exposure to toxins during warfare or strenuous physical activity are possible reasons for why some veterans and athletes may be at increased risk of developing ALS.

Although there has been no consistent association between any environmental factor and the risk of developing ALS, future research may show that some factors are involved in the development or progression of the disease.

Support Groups

Salt Lake City MDA/ALS Group Meeting

Date & Time: First Tuesday monthly, 6pm-8pm

Location: Sanderson Community Center
5709 South 1500 West Taylorsville, UT 84123

ALS Association-Sponsored Family Support Group in Riverton

Date & Time: 2nd Tuesday of the month
2 pm - 3:30 pm

Location: Riverton Senior Center
Room D
12914 Redwood Rd.
Riverton, UT 84065

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ALS Association-Sponsored Family Support Group in Roy

Date & Time: 3rd Thursday of the month
6 pm - 7:30 pm

Location: First Baptist Church of Roy
2025 W 5700 S
Roy, UT 84067
Riverton, UT 84065

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ALS Association-Sponsored Family Support Group in Lindon

Date & Time: 4th Tuesday of the month
1 pm - 2:30 pm

Location: Lindon Senior Center
25 Main St.
Lindon, UT 84042

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Please contact the MDA office in Boise for more information: 208-327-0107.

National Associations

Muscular Dystrophy Association (MLDA)

National office phone number: 800-572-1717
Utah MDA phone number: 801-278-6200 
Idaho MDA phone number: 208-327-0107 MDA-ALS

Learn More about the Muscular Dystrophy Association

ALS Association

ALS Association national office phone: 818-880-9007
The ALS Association Rocky Mountain Chapter phone: 303-832-2322

Learn More about the National ALS Association

Learn More about ALS Treatment & Research