What Is ALS? Symptoms, Causes, Diagnosis, Treatment, and Prevention

ALS, or amyotrophic lateral sclerosis, is caused by the death of nerve cells in the brain and spinal cord — called motor neurons — that control voluntary muscle movements such as chewing, walking, and talking.

Over time, people who have ALS lose their ability to walk, use their hands and arms, speak, chew, and swallow.

The term “amyotrophic” was first used in the mid-19th century and derives from Greek roots meaning “without” (a) “muscle” (myo) and “food” (troph). The word conveys the idea that the muscles aren’t getting what they need to function properly.

“Lateral” refers to the parts of the spinal cord where the nerve cells that control the muscles are found. The degeneration of this area results in scarring or hardening (“sclerosis”), which further interferes with the transmission of nerve signals. (1)

ALS is also called Lou Gehrig’s disease because the well-known New York Yankees baseball player was diagnosed with it in 1939 when he was 36; he died two years later.

The disease is progressive, meaning the symptoms people experience get worse over time. There is no cure or effective treatment for the disease.

Early symptoms of ALS are often subtle and may be overlooked. They may include muscle twitching, cramping, stiffness, or weakness.

Over time, people with ALS may develop slurred speech, difficulty chewing and swallowing, and weaker, visibly thinner muscles.

Symptoms of ALS may include: (2)

• Difficulty walking; tripping and falling
• Weakness in the legs, feet, or ankles
• Weakness in the hands
• Muscle cramps in the arms, shoulders, and tongue
• Inappropriate crying, laughing, or yawning
• Memory and behavioral changes

Although the signs and symptoms of the condition vary from person to person, depending on which neurons are affected, it most often starts in the hands, feet, or limbs before spreading to other parts of the body.

As ALS progresses and nerve cells are destroyed, the muscles get weaker. This eventually affects a person’s ability to chew and swallow food, speak, and breathe.

There’s generally no pain in the early stages of ALS, and it’s rare even in the later stages. ALS doesn’t usually affect your bladder control or your senses.

Learn More About Signs and Symptoms of ALS

ALS has been linked with chemical imbalances in the brain or central nervous system. In some people, the condition may be caused by a malfunctioning immune system, while others may inherit a genetic mutation that predisposes them to it.

Still, in most people with ALS, the condition appears to develop randomly. These people have what’s called sporadic ALS.

While there is still much that researchers don’t know about who will get ALS and why, the following factors can put you at higher risk for developing ALS: (3)

Genetics 5 to 10 percent of people with ALS inherit it from one of their parents.

Age Although ALS can develop at any age, your risk increases with age, with 55 being the average age of diagnosis.

Sex Men are slightly more likely than women to develop ALS before age 65. After age 70, the risk is the same for men and women.

Race and Ethnicity White people and non-Hispanics are at increased risk of developing ALS.

Smoking Tobacco smoking appears to increase the risk of ALS, especially in women who are post-menopausal.

Exposure to Toxins Some studies link lead and other substances to ALS. While many studies have been done on the topic, none have proved that a particular agent or chemical is definitively associated with ALS. More research is being conducted on possible causes, such as toxic or infectious agents, viruses, physical trauma, and diet, as well as behavioral and occupational factors.

Military Service The U.S. Department of Veterans Affairs recognizes ALS as a service-connected disease. There is some evidence that those who have served in the military are at higher risk of ALS, with some studies putting veterans at about 1.5 to 2 times more likely to develop the disease. The reason for this increased risk isn’t known. Speculation revolves around exposure to metals, chemicals, or pesticides during warfare; traumatic injuries; viral infections; and extreme physical exertion.

High Glutamate Levels In addition, some people with ALS have increased levels of glutamate, a chemical messenger in the brain, around the nerve cells in spinal fluid. Too much glutamate is toxic to some nerve cells, and may contribute to the development of ALS.

Faulty Immune Response The condition has also been linked with a “disorganized” immune response, in which the immune system attacks and kills some normal nerve cells. This attack could cause ALS.

Virus Cells There’s also some evidence that the condition may have a viral link. Some studies have found that people with ALS have virus cells in their spinal cords. (4)

These viral cells have similar properties to echovirus-7, which causes meningitis and rare cases of encephalitis.

Abnormal Proteins Finally, research suggests that the formation of abnormal proteins in nerve cells can cause the condition by destroying the affected nerve cells. More research is needed to understand this process.

Types of ALS

Many different types of ALS have been identified. The most common forms are sporadic ALS and familial ALS.

Research indicates that 90 percent or more of ALS is sporadic, meaning it appears to develop randomly in people of all ages and racial and ethnic backgrounds around the world. The individuals who develop sporadic ALS don’t have any known risk factors for ALS or a family history of the disease. (1,3)

But family members of people with sporadic ALS do have a slightly higher risk of developing the disease.

About 5 to 10 percent of all cases of ALS in the United States are familial or genetic, meaning inherited from a parent. Family members who have familial ALS (FALS) most often have a 50 percent chance of passing the gene mutation on to their children.

About 25 to 40 percent of all familial cases (and a small percentage of sporadic cases) are caused by a defect in a gene called “chromosome 9 open reading frame 72,” or C9ORF72.

This mutation has also been connected to atrophy of the frontal and temporal lobes of the brain, which causes frontotemporal lobe dementia. Some people with this mutation show signs of both motor neuron and dementia symptoms.

Mutations in the SOD1 gene, which is associated with the production of the enzyme copper-zinc superoxide dismutase 1, occurs in 12 to 20 percent of familial cases. (5)

Because the symptoms of ALS tend to come on slowly, it can take some time to reach a definitive diagnosis.

Once a neurological disease is suspected, a neurologist will conduct a variety of exams and tests to narrow down the diagnosis, including:

• Electromyogram (EMG)
• Nerve conduction study
• Magnetic resonance imaging (MRI)
• Blood and urine tests
• Spinal tap
• Muscle biopsy
• Genetic testing

Electromyogram In an EMG, your doctor inserts a needle electrode through your skin into various muscles. This test measures the electrical activity of your muscles when they contract and when they’re at rest.

If abnormal electrical activity is spotted, that’s an indication you may have ALS. The findings on this test can also help guide exercise therapy for your ALS.

Nerve Conduction Study A nerve conduction study measures the ability of your nerves to send impulses to muscles in different parts of your body. This test can spot nerve damage or certain diseases of the muscles or nerves.

MRI MRI uses radio waves and a powerful magnetic field to produce detailed images of your brain and spinal cord. It can reveal spinal cord tumors, herniated disks in your neck, and other conditions that might be causing your symptoms.

Blood and Urine Tests Analyzing samples of your blood and urine can also help your doctor rule out other possible causes of your signs and symptoms, including autoimmune disorders.

Spinal Tap In a spinal tap or lumbar puncture, a surgeon will remove a sample of your spinal fluid for laboratory testing using a small needle inserted between two vertebrae in your lower back.

Muscle Biopsy Finally, a muscle biopsy can be used to rule out other causes of your symptoms. Under local anesthesia, a surgeon will remove a small portion of your muscle and send it to a lab for analysis.

Genetic Testing for Familial ALS

If ALS appears to run in your family, genetic testing may be an option to help you understand your risk. A genetic test can determine if the disease is caused by mutated genes that are inherited.

About 60 to 70 percent of people with FALS will have a positive genetic test result, meaning a mutation is identified. (3)

Genetic testing doesn’t change the course of medical treatment if you already have ALS. It doesn’t diagnose ALS in people without symptoms, and it doesn’t identify when a person may get ALS or display symptoms.

Some insurance plans cover genetic testing for ALS, and others do not. Check with your insurance company for details before being tested. (6)

To undergo a genetic test, see a genetic counselor, who can tell you if you are a candidate for testing. To find a genetic counselor in your area, visit the National Society of Genetic Counselors.

The counselor may recommend testing if there is more than one person with ALS or frontotemporal dementia in your family, or you have a family member who was diagnosed at a younger age, such as 45 or younger. (7)

A genetic counselor will take a detailed medical and family history, evaluate your risks, and talk to you about what genetic testing involves. You’ll also learn the pros and cons of genetic testing.

If a mutation is not identified but ALS is prevalent in a family, the family may have FALS caused by a gene or genes that have not been discovered yet. Because of this, even if genetic testing doesn’t reveal a genetic mutation, other family members may still be at risk for developing the disease.

If no genetic mutation is identified in a person with ALS, then testing other family members who don’t have ALS may not be helpful, since there is no mutation to test for.

When a mutation is identified in a person with ALS, family members can also get tested to see if they inherited the same genetic mutation. Before relatives are tested, however, they may be required to have a neurological exam, a psychological assessment, and counseling.

Since FALS tends to occur in adulthood, genetic testing for the disease is not recommended in kids younger than 18.

A healthcare professional has to order genetic testing for you; you can’t request it from a laboratory on your own. The test itself may involve drawing blood or spitting into a tube.

You’ll get the results within a few weeks to a few months, depending on the type of testing you’re having done. The doctor who ordered the test will most likely give you the results, either in person or over the telephone.

Be advised that test results can be difficult to interpret, so you may not get the clear, yes-or-no answer you were hoping for.

In addition, some people may be worried that getting tested for ALS could bring about employment discrimination or insurance discrimination. The Genetic Information Nondiscrimination Act of 2008 (also called GINA) is a federal law that protects people from genetic discrimination in health insurance and employment as it relates to a family history of ALS or a positive genetic test result. Visit the GINA website or the Genetic Alliance for more information.

Prognosis of ALS

ALS generally progresses rapidly. But proactive treatment can extend life and improve quality of life for people with the condition.

Recent estimates suggest that today, more than half of those diagnosed with the condition survive for no more than three years after learning they have it. This is about the average lifespan for people with ALS.

Roughly one in four people with ALS survive for 5 to 10 years after diagnosis, and 10 percent survive 10 years or more.

Almost everyone with the condition develops respiratory weakness, and most people with it die from lung-related complications. (8)

As there isn’t a cure for ALS, people diagnosed with the condition will have it for the rest of their lives.

Once ALS starts, it almost always progresses, taking away your ability to walk, dress, write, speak, swallow, and breathe without assistance.

Still, how fast and in what order this occurs varies from person to person. Progression can sometimes slow down or speed up, meaning you may have periods lasting weeks to months where there’s very little or no loss of function.

These ALS “stops” and “starts” are usually temporary. Less than 1 percent of people with ALS will have significant improvement in function lasting 12 months or longer, although there have been extremely rare cases in which a person experiences significant improvement and recovery of lost function after treatment. (9)

There’s no cure for ALS. Treatment of the condition is focused on maintaining physical function and independence for as long as possible.

Treatments can’t reverse the muscle and nerve damage caused by ALS, but they can slow the progression of symptoms, prevent complications, and help keep you pain-free.

Ideally, you should have several different doctors trained in many areas — including a neurologist and physiatrist — and other healthcare professionals (like a physical therapist and occupational therapist) as part of your care team. For example, psychological treatment for depression, and social and practical help for caregivers, are important parts of treating ALS.

Advance Care Planning

Among other things, your medical team should help you plan ahead for the symptoms and other challenges related to ALS that you are likely to encounter over the course of your disease.

Those discussions should include your personal values, life goals, and preferences regarding your immediate, and future, medical care. It should also include end-of-life planning.

You don’t have to decide on everything right away. You and your medical team can — and should — discuss your options for supportive care as symptoms arise.

But you shouldn’t wait too long to formulate advance care directives that spell out your wishes regarding your care and your preferences for life-sustaining treatments.

Advance care directives include two main elements:

• Durable Power of Attorney for Healthcare A durable power of attorney for healthcare is a legal document in which you name your healthcare proxy, or the person who will make healthcare decisions on your behalf should you become unable to do so.
• Living Will A living will spells out how you’d like to be treated if you are dying or permanently unconscious and cannot make your own decisions about emergency treatment. For a person with ALS, such treatment might include connecting you to a ventilator to help you breathe, and inserting a feeding tube through your nose or directly into your stomach through a surgically created opening.

Creating advance care directives, and putting them in writing, helps to ensure that your family members and other caregivers understand your wishes, and they also lower the likelihood that you’ll receive treatment you don’t want. Keep in mind that you can update all these documents at any time. Ultimately, the choice is yours whether to accept or decline treatment that will prolong your life with ALS.

To learn more about the process of creating healthcare directives, check out the guidelines offered by the National Institute on Aging.

Medication Options

There are two prescription drugs approved by the U.S. Food and Drug Administration (FDA) for use in people with ALS.

Taken orally, riluzole (Rilutek) — sold in tablet form and as a thickened liquid — has been shown to increase life expectancy in people with the condition by 3 to 6 months by protecting the nerves in the brain and spinal cord from damage caused by glutamate. It’s designed to prolong lung function and delay the need for mechanical ventilator support to help people with ALS breathe.

The drug can cause side effects, including dizziness, gastrointestinal problems, and liver function problems. If you’re taking riluzole, your doctor should monitor your blood counts and liver function to assess the effect of the drug on your liver.

Edaravone (Radicava) is given by intravenous (IV) infusion, and it may slow the decline in everyday function in people with ALS. It’s administered daily for two weeks a month.

Edaravone is designed to disrupt oxidative stress, which causes the death of nerve cells in people with ALS. Taking the drug, you may experience side effects like bruising around the injection site, headache, and shortness of breath.

Your doctor may recommend other prescription and over-the-counter (OTC) medications to manage other symptoms of ALS, like:

• Muscle relaxants for cramps and spasms
• Laxatives for constipation
• Pain medication
• Antidepressants

Breathing Assistance

As your ALS progresses, you’ll likely have more difficulty breathing as the muscles around your lungs weaken. Your doctor should test your breathing regularly.

If your breathing is diminished, your doctor may recommend a device called a continuous positive airway pressure (CPAP) machine to assist you, particularly at night. A CPAP machine delivers pressurized air into your airway through a mask that you wear over your mouth and nose, or through small tubes inserted into your nostrils.

Eventually, you may need what is called “invasive” ventilation to help you breathe. In this case, a tracheostomy is done to surgically create a hole at the front of your neck, leading to your windpipe. A tube connected to a ventilator is then inserted into the hole so that air can be delivered to your lungs.

For some people, mechanical ventilation via tracheostomy yields months or years of good quality of life; for others, it doesn’t. The choice to proceed to a tracheostomy is individual, and you should discuss the pros and cons of doing so with your doctor and loved ones, ideally before you need to make a decision about it.

Physical and Occupational Therapies

In addition to prescription and OTC medication, your doctor may recommend other therapies to treat your ALS. (10)

For example, a physical therapist can teach you stretches and exercises to reduce pain and improve walking ability and recommend braces and equipment (wheelchairs and walkers) to help you remain mobile and independent. Research has found that low-impact exercises can help maintain your heart health, muscle strength, and range of motion.

An occupational therapist can help you find ways to perform tasks using your hands and arms even if they’re weak from ALS. They can recommend adaptive equipment to help you get dressed, eat, and perform other daily activities on your own, and help you modify your home to improve its accessibility.

A speech therapist can teach you adaptive techniques to make your speech more understandable. They can also help you explore other methods of communication, like an alphabet board or electronic devices.

Alternative and Complementary Therapies for ALS

Certain complementary therapies that may be useful in ALS include: (11)

• Meditation to relieve stress
• Acupuncture to manage pain, as well as muscle cramps and spasms
• Massage therapy to reduce stress and pain

Although several herbal remedies and nutritional supplements sold online and elsewhere may promise benefits for people with ALS, there’s little research supporting their use. They may also affect how well your prescription medications work.

Learn More About Treatment for ALS: Medication, Alternative and Complementary Therapies, Surgery Options, and More

Prevention of ALS

There is no way to prevent ALS, as the exact underlying cause of the condition remains unknown. (12)

Researchers are currently studying ALS to learn what causes it and, potentially, how to prevent it from developing. People with ALS can participate in these studies through the National ALS Registry and the National ALS Biorepository.

In addition, the CDC maintains a database of the multidisciplinary ALS clinics that are leading these studies and are working on ways to improve the quality and length of life of people living with the condition.

Potential health complications associated with ALS are: (5)

• Lung aspiration (the breathing in of food or fluid)
• Loss of independence (the ability to care for yourself)
• Lung failure
• Pneumonia
• Excessive weight loss
• Pressure sores (or bed sores) (14)

Pressure sores are areas of damaged skin. They usually result from staying in one position for long periods of time, and they may occur in ALS as your mobility worsens.

You’re at risk for pressure sores if you’re bedridden, use a wheelchair, or are unable to change your position on your own.

Pressure sores typically form in parts of the body where your bones are close to your skin, like your ankles, back, elbows, heels, and hips.

ALS occurs around the world and affects all races and ethnic groups. In the United States, ALS affects approximately 5 out of every 100,000 people, according to the National ALS Registry, released by the CDC.

That translates into about 30,000 people nationwide. An estimated 5,000 new cases are diagnosed each year in the United States.

ALS affects more males than females. Approximately 60 percent of those with the condition are men, and 40 percent are women.

While people can get ALS at any age, most are diagnosed between age 40 and 70. In addition, 20 out of every 100,000 people between age 70 and 79 are diagnosed with the condition. (3)

Researchers are trying to better understand the mechanisms that selectively trigger motor neurons to degenerate in ALS, and to find effective approaches to halt cell death. For example, ongoing studies are looking at how and why potentially ALS-causing gene mutations lead to the destruction of neurons.

In addition, researchers are looking into new treatments for the condition, including gene therapy approaches, antibodies, and cell-based therapies. This research is still in the early stages.

Recent estimates suggest ALS is far more common among white Americans than among Black, Indigenous, and People of Color (BIPOC) populations in the United States.

In a study that looked at ALS prevalence in three U.S. states and eight metropolitan areas, close to 75 percent of ALS cases occurred in white Americans, while just under 10 percent occurred in Black Americans. Less than 4 percent of the people with ALS represented in the study were Asian American, and roughly 11 percent were Hispanic. (15)

Black Americans and ALS

White Americans are more than twice as likely to be diagnosed with ALS as Black Americans. (16)

The condition is less common among Black Americans, and they appear to have a better prognosis than white Americans. A study published in 2019 found that Black Americans with ALS lived longer than white Americans with the condition, perhaps because they were more likely to undergo a tracheostomy. (17)

ALS shares symptoms with the following disorders: (4)

• Primary lateral sclerosis
• Kugelberg-Welander syndrome
• Focal or monomelic motor neuron disease
• Progressive bulbar palsy
• Progressive muscular atrophy

Primary lateral sclerosis (PLS) is a very rare neurological disorder that causes progressive weakness of the muscles of the arms and legs, without wasting or atrophy. This loss of neurological function progresses slowly and results in spastic movements of the hands, feet, or legs, and it may affect your ability to walk.

Kugelberg-Welander syndrome, which is also called spinal muscular atrophy, is an inherited neurological disorder that occurs in infancy and causes progressive muscle weakness, particularly in the legs. It may also cause breathing problems.

Focal or monomelic motor neuron disease affects only one area of the body, usually the shoulder muscles. The disease progresses over several months, and some people eventually develop more extensive motor neuron disease.

Progressive bulbar palsy or pseudobulbar palsy causes muscle weakness and wasting (atrophy), frequently in the areas around the lips, tongue, and voice box. People with this condition may have difficulty speaking and swallowing.

Progressive muscular atrophy causes muscle weakness and wasting (atrophy) in the lower body, particularly the legs.

Finally, very rarely, some people with HIV may experience a complication that resembles ALS. It can be reversed with antiviral therapy designed to treat the infection.

ALS is a complicated disease that has a huge impact on an individual’s and a family’s life. The good news is that a number of organizations can help you understand what’s going on and connect you to sources of support, education, and information about ongoing ALS research.

Best Sources of Support and Information

ALS Association

The ALS Association advocates for people living with ALS, funds ALS research, and offers a variety of resources to people with ALS and their families and caregivers. The association has chapters in several U.S. states. Search online for your local state chapter.

ALS Therapy Development Institute

The ALS Therapy Development Institute is a nonprofit drug discovery lab focused solely on ALS. Its website also offers resources for individuals affected by ALS.

Compassionate Care ALS

This nonprofit organization provides resources not typically covered by health insurance, including equipment, educational workshops, Medicare and Medicaid assistance, and guidance for living with ALS, caregiving, and exploring end-of-life issues.

Les Turner ALS Foundation

The Les Turner ALS Foundation is a nonprofit organization based in Illinois that funds the Les Turner ALS Center at Northwestern Medicine, in Chicago. The foundation additionally provides a variety of support services for people affected by ALS.

Muscular Dystrophy Association (MDA)

The MDA supports research on muscular dystrophy, ALS, and related muscle-debilitating diseases that take away physical strength, independence, and life. They additionally advocate for people affected by ALS, offer free educational seminars, and partner with the CDC to promote the National ALS Registry.

Where to Learn About ALS Clinical Trials and Other Research

If you’d like to know more about ALS research or participate in research, these resources can help you find the information you need:

National ALS Registry

The National ALS Registry is a program to collect and analyze data about persons living with ALS. By joining the registry, you help researchers learn more about risk factors for ALS and about how the disease typically progresses over time.

NIH NeuroBioBank

The NIH NeuroBioBank is a network of six brain and tissue sample repositories that distribute those samples to the research community to study neurological, neuropsychiatric, and neurodevelopmental diseases and disorders.

Northeast Amyotrophic Lateral Sclerosis Consortium (NEALS)

The mission of NEALS is to rapidly translate scientific advances into clinical research and new treatments for people with ALS and motor neuron disease. Its website has a Contact an ALS Specialist search feature.

Project ALS

Project ALS is currently focused on initiating a phase 1 clinical trial of the investigational ALS drug Prosetin.

ALS Untangled

This research group studies alternative and off-label treatments as possible treatments for ALS.

Favorite ALS Fundraisers

Many medical conditions have fundraisers associated with them. People run marathons, do walkathons, or participate in organized bike rides or golf tournaments to raise money for research and treatment. ALS has all these, but the most famous fundraiser associated with ALS is, no doubt, the Ice Bucket Challenge.

Ice Bucket Challenge

The Ice Bucket Challenge — in which a brave person dumps a bucket of ice and water over his own head, challenges others to do the same, and donates money toward ALS awareness and research — has become associated with ALS. It has actually raised millions of dollars for the cause, and some of the research it has funded has had real results that may change the landscape of ALS understanding and treatment. Much of the money raised by the Ice Bucket Challenge goes to the ALS Association, which offers details on how the money is spent on its website.

ALS Therapy Development Institute Fundraisers

The institute has created several of its own signature fundraising programs, many of which went virtual in 2020, and offers resources to individuals who wish to start their own ALS fundraisers.

Additional reporting by Brian P. Dunleavy.