Disorders

What is amyotrophic lateral sclerosis (ALS)?

Reviewed May 2026 by J. David Avila, MD, FAAN

Definition: Amyotrophic lateral sclerosis (ALS) is a progressive disease that affects the nerve cells that control muscle movement. As those nerve cells become damaged, it becomes harder for the brain to send signals to the muscles.

As ALS progresses, people may lose strength and mobility, and everyday activities can become more difficult. While ALS mainly affects movement, some people also notice changes in thinking or behavior.

ALS most often develops in mid-to-late adulthood, but it can occur at any age.

ALS is almost always fatal, usually because the muscles needed for breathing become too weak. On average, people live with ALS for about three to five years, but up to 10% will live for 10 years or more.

What are the symptoms of ALS?

ALS often begins with subtle changes that become more noticeable over time.

Early symptoms may include:

  • Weakness in the hands, arms, legs, or feet
  • Muscle twitching or cramping
  • Changes in speech or difficulty swallowing

As the disease progresses, symptoms may include:

  • Difficulty walking or using hands
  • Trouble speaking clearly or being understood
  • Difficulty eating and maintaining weight
  • Shortness of breath as breathing muscles weaken

Everyone’s experience with ALS is different. Some people notice slow changes over time, while others experience faster progression.

What are the causes and risk factors of ALS?

Researchers are still working to understand exactly why ALS develops.

  • Most cases happen without a clear cause or family history.
  • A smaller number of cases are linked to inherited genetic changes.
  • Age and genetics can both affect risk.

ALS is a complex condition, and ongoing research continues to uncover new insights about its causes and risk factors.

How is ALS diagnosed?

ALS can be hard to diagnose early because its symptoms can overlap with those of other neurological or muscle conditions.

To diagnose ALS, a neurologist combines a clinical evaluation with specialized tests to look for signs of nerve damage and rule out other possible causes.

  • Detailed medical history and neurological exam: Your neurologist will assess muscle strength, reflexes, coordination, and speech. They also look for signs of problems with your upper and lower motor neurons—nerve cells in your brain and spinal cord that work together to control movement.
  • Electromyography (EMG) and nerve conduction studies: These tests show how well nerves and muscles are working. EMG can detect abnormal electrical activity in muscles, which may point to ongoing nerve damage—even in areas without obvious symptoms.
  • Imaging (such as MRI of the brain and spinal cord): MRI scans help rule out other conditions that can cause similar symptoms, such as multiple sclerosis, spinal cord disorders, or
  • Laboratory and additional testing, when needed: Depending on the situation, neurologists may also order:
    • Blood tests to rule out metabolic or autoimmune conditions
    • Spinal fluid testing (lumbar puncture)
    • Genetic testing, especially if there is a family history of ALS

What treatments are available for ALS?

There is currently no cure for ALS, but treatment can help manage symptoms, support daily life, and in some cases help people live longer.

Care may include:

  • Medications that may slow disease progression
    • Riluzole: This was the first medication approved for ALS. It works by reducing levels of glutamate, a chemical in the brain that can damage nerve cells when present in excess.
    • Edaravone: This treatment acts as an antioxidant, helping protect nerve cells from damage. It may slow the decline in physical function, especially for some people earlier in the disease course.
    • Tofersen: This newer treatment is designed for people with a mutation in the SOD1 gene. It targets the genetic source of the disease to reduce production of a harmful protein.
  • Treatments to manage symptoms like muscle stiffness, pain, or excess saliva
  • Breathing support when needed
  • Nutrition support to help maintain weight and strength

Supportive care is also an important part of ALS treatment. Many people benefit from working with a team of specialists who can support physical, emotional, and everyday needs.

Caring for and navigating ALS

Explore practical tips, personal stories, and expert guidance for living well with ALS.

Frequently asked questions

How does ALS affect breathing, and when is support needed?

ALS can weaken the muscles used for breathing. Early signs may include shortness of breath during activity or trouble sleeping comfortably. Breathing support methods like noninvasive ventilation (a machine that helps you breathe through a mask or mouthpiece) can improve comfort and quality of life. Care teams monitor breathing closely and help guide next steps based on each person’s needs.

What assistive technologies can help people with ALS stay independent longer?

A range of tools can help people with ALS stay active, safe, and connected for longer, including:

  • Mobility devices such as braces or wheelchairs
  • Communication tools that help when speaking becomes difficult
  • Home adaptations that make daily tasks easier

Using these tools early can make a meaningful difference in independence, comfort, and confidence.

What kind of care team can support someone living with ALS?

ALS care is often strongest when it is coordinated across a team that can support changing needs over time. That team may include:

  • Neurologists
  • Respiratory therapists
  • Speech and physical therapists
  • Nutrition specialists
  • Psychologists or psychiatrists
  • Palliative care specialists
  • Social workers and support services
What nutritional changes or feeding options can be considered?

Eating and maintaining weight can become harder with ALS. Care teams may recommend:

  • Adjusting food textures to make swallowing safer
  • Adding calories to maintain energy and strength
  • Considering a feeding tube when getting enough nutrition by mouth is no longer possible

These decisions are personal and are best made together with care teams and loved ones.