Amyotrophic lateral sclerosis, widely known as ALS or Lou Gehrig’s disease, is a progressive disease that gradually destroys the nerve cells controlling voluntary muscle movement. Over time it affects walking, speaking, swallowing, and eventually breathing, while thinking and the senses are often preserved. There is no cure yet, and ALS remains a serious diagnosis, but research is moving quickly: the first therapy targeting a genetic cause was approved in 2023, and blood-based tools are beginning to speed diagnosis. This guide explains what ALS is, its symptoms, causes, how it is diagnosed, the treatments and supportive care that help people live as well as possible, and the latest scientific advances.
What is ALS (Lou Gehrig’s disease)?
ALS is a neurodegenerative disease in which the motor neurons, the nerve cells in the brain and spinal cord that tell muscles to move, progressively break down and die. As these cells are lost, the brain can no longer control voluntary movement, and muscles weaken and waste away. The name is descriptive: “amyotrophic” refers to muscle wasting, and “lateral sclerosis” to hardening in the parts of the spinal cord affected. It is called Lou Gehrig’s disease after the baseball player diagnosed with it in 1939.
ALS usually begins between ages 60 and 80, and about 5,000 people are diagnosed each year in the United States. It is progressive, and most people survive about 3 to 5 years after symptoms begin, most often because the muscles used for breathing weaken; however, roughly 1 in 10 people live 10 years or longer, and the course varies from person to person. Importantly, ALS is not contagious.
Symptoms of ALS
ALS often starts subtly and in one part of the body before spreading. Early symptoms commonly include muscle twitching, called fasciculations, along with cramping, stiffness, and weakness, frequently first noticed in a hand, an arm or leg, or in the muscles used for speech and swallowing. Because the first signs can be mild, ALS is sometimes mistaken for other conditions early on.
As the disease progresses, weakness spreads and deepens, leading to difficulty walking, using the hands, speaking clearly, chewing, and swallowing. Eventually the muscles that control breathing are affected, which is the most serious complication. In most people, the senses, and often thinking and memory, remain largely intact, although a minority develop changes in thinking or behavior. Recognizing the pattern of progressive, painless muscle weakness is key to seeking evaluation early.
What causes ALS?
In most people the cause of ALS is not known. About 90 to 95 percent of cases are sporadic, meaning they occur without a family history, while 5 to 10 percent are familial, running in families and linked to specific gene changes. The two best-known genes are C9orf72, the most common genetic cause, and SOD1, which matters greatly for treatment because a therapy now targets it directly.
Researchers believe ALS results from a combination of genetic susceptibility and other factors that damage motor neurons over time, including problems with protein handling and inflammation within nerve cells. Genetic testing is recommended for people with a family history of ALS or a related condition, and it is required to determine eligibility for the SOD1-targeted therapy. For most people without a family history, though, ALS cannot be traced to a single cause.
How ALS is diagnosed
There is no single test that confirms ALS, so diagnosis is clinical, based on a neurological exam showing progressive muscle weakness with signs of both upper and lower motor neuron damage, combined with tests that rule out conditions that can mimic it. Electromyography and nerve conduction studies, which measure the electrical activity of muscles and nerves, are central to supporting the diagnosis, and MRI and blood tests help exclude other causes.
Two developments are making diagnosis faster and more confident. The Gold Coast criteria, introduced in 2020, simplified the standard for diagnosing ALS, and a blood marker of nerve damage called neurofilament light chain is increasingly used to support the diagnosis and track progression, since levels are typically much higher in ALS. As part of ruling out muscle diseases, doctors may also check muscle enzymes such as creatine kinase, and understanding the creatine kinase levels measured by a CPK test can help you follow that step. Because several conditions cause overlapping weakness, clinicians work to distinguish ALS from disorders such as the neuromuscular-junction weakness of myasthenia gravis and the nerve-insulation damage of multiple sclerosis. Learning how to read the flags and reference ranges on a lab report can help make sense of these tests.
Treatment options for ALS
There is no cure for ALS, but treatment can slow the disease for some people, ease symptoms, and support quality of life, and multidisciplinary care is the foundation. Two medicines, riluzole and edaravone, are used to modestly slow the disease or its functional decline, and a newer gene-targeted therapy is available for a specific inherited form.
| Treatment | Role |
|---|---|
| Riluzole | Oral medicine that may extend survival by several months |
| Edaravone | Can slow the decline in daily function for some people |
| Tofersen | A gene-targeted therapy for the inherited SOD1 form of ALS |
| Supportive care | Physical, occupational, and speech therapy, nutrition, and breathing support |
Beyond medication, a coordinated team of neurologists, therapists, respiratory and nutrition specialists, and mental health support helps people manage symptoms and maintain independence and comfort. Devices that assist communication, mobility, and breathing, such as noninvasive ventilation, can meaningfully improve quality of life and, in the case of breathing support, survival. The field also learns from setbacks, such as the 2024 withdrawal of one drug after a larger trial did not confirm benefit, which underscores the importance of rigorous testing.
Living with ALS and long-term outlook
ALS affects each person differently, and while it is a serious, progressive disease, planning and comprehensive care can help people live as fully and comfortably as possible. Care focuses on preserving function, managing symptoms such as cramps, excess saliva, and difficulty swallowing, and supporting breathing and nutrition as needs change. Emotional and practical support for both the person and their caregivers is a central part of living with ALS.
Because the disease progresses, care teams help with proactive planning around communication tools, mobility equipment, and decisions about breathing support, always guided by the person’s own wishes and values. Support organizations and specialized ALS clinics provide resources that improve both quality and length of life, and ongoing research continues to expand what is possible.
Latest scientific advances in ALS research
ALS research is advancing on treatment, diagnosis, and biomarkers at once. According to PubMed-indexed research, a 2026 study in JAMA Neurology examined tissue from people with the SOD1 form of ALS who had been treated with the gene-targeted drug tofersen and found that the drug reached the spinal cord and brain and substantially reduced the harmful SOD1 protein (Guise et al., 2026). What this means for you: this is direct human evidence that the first gene-targeted ALS therapy actually engages its target in the nervous system, reinforcing the value of genetic testing to identify who may benefit.
A 2026 study in Muscle & Nerve reported that adding the blood biomarker neurofilament light chain to the standard diagnostic criteria sharply improved the ability to predict who would go on to have definite ALS (Smith et al., 2026). What this means for you: a simple blood test used alongside the exam and nerve studies could help doctors reach a diagnosis earlier and with more certainty, addressing a delay many people experience. On the treatment front, a 2026 phase 2b trial in JAMA Neurology of an investigational oral drug called PrimeC found slower functional decline and a lower risk of hospitalization, respiratory failure, or death with continuous treatment (Cudkowicz et al., 2026). What this means for you: it is an early but encouraging signal that supports a larger confirmatory trial of a potential new option alongside existing therapies.
Glossary of key ALS terms
| Term | Definition |
|---|---|
| Motor neuron | A nerve cell that carries signals from the brain and spinal cord to muscles. |
| Fasciculations | Small, involuntary muscle twitches, a common early sign of ALS. |
| Sporadic ALS | ALS that occurs without a family history, the great majority of cases. |
| Familial ALS | Inherited ALS linked to specific gene changes such as C9orf72 or SOD1. |
| Electromyography | A test of the electrical activity of muscles used to support an ALS diagnosis. |
| Neurofilament light chain | A blood and spinal-fluid marker of nerve damage, elevated in ALS. |
| Noninvasive ventilation | Breathing support through a mask that can improve comfort and survival. |
Frequently asked questions about ALS
What is ALS?
ALS, or amyotrophic lateral sclerosis, is a progressive disease that destroys the motor neurons controlling voluntary muscle movement, leading to weakness in the limbs, speech, swallowing, and eventually breathing. Thinking and the senses are usually preserved. It has no cure yet but can be managed with medication and supportive care.
Is ALS the same as Lou Gehrig’s disease?
Yes. Lou Gehrig’s disease is another name for ALS, named after the baseball player diagnosed with it in 1939. The two terms refer to the same condition.
What are the early signs and symptoms of ALS?
Early signs often include muscle twitching, cramps, stiffness, and weakness, frequently starting in one hand, arm, or leg, or in the muscles used for speech and swallowing. Because these symptoms can be subtle and resemble other conditions, evaluation by a neurologist is important.
What causes ALS, and is it hereditary?
Most ALS is sporadic, with no known cause or family history. About 5 to 10 percent is familial and linked to gene changes such as C9orf72 and SOD1. Genetic testing is recommended when there is a family history and is required to determine eligibility for the SOD1-targeted therapy.
What is the life expectancy after an ALS diagnosis?
Most people survive about 3 to 5 years after symptoms begin, usually due to weakening of the breathing muscles, though roughly 1 in 10 live 10 years or more. The course varies widely, and breathing and nutrition support can extend both quality and length of life.
Is there a cure or new treatment for ALS?
There is no cure, but riluzole and edaravone can modestly slow the disease or its decline, and a gene-targeted therapy called tofersen is available for the inherited SOD1 form. Multidisciplinary supportive care is essential, and research into new treatments is active.
Sources
- National Institute of Neurological Disorders and Stroke — Amyotrophic Lateral Sclerosis (ALS) — NINDS, 2024 — ninds.nih.gov
- Mayo Clinic Staff — Amyotrophic Lateral Sclerosis: Symptoms and Causes — Mayo Clinic, 2024 — mayoclinic.org
- MedlinePlus, National Library of Medicine — Amyotrophic Lateral Sclerosis — MedlinePlus Genetics, 2024 — medlineplus.gov
- Guise AJ, Sellon MT, Roemer SF, et al. — Antisense Oligonucleotide Tofersen Distribution in the Central Nervous System of SOD1-ALS Autopsy Tissue Donors — JAMA Neurology, 2026 — doi.org/10.1001/jamaneurol.2026.2195
- Smith SE, Miller TM, Atkinson A, et al. — Integrating Serum Neurofilament Light Chain Into Amyotrophic Lateral Sclerosis Diagnostic Criteria — Muscle & Nerve, 2026 — doi.org/10.1002/mus.70212
- Cudkowicz M, Drory VE, Chio A, et al. — Safety and Efficacy of PrimeC in Amyotrophic Lateral Sclerosis: The PARADIGM Randomized Clinical Trial — JAMA Neurology, 2026 — doi.org/10.1001/jamaneurol.2026.0230
Further reading
- See how a muscle-damage enzyme is used in the workup in this guide to the creatine kinase levels on a CPK test.
- Compare ALS with another cause of muscle weakness in this guide to the neuromuscular disease myasthenia gravis.
- Explore another progressive neurological condition in this guide to the nerve damage of multiple sclerosis.
- Learn about a movement disorder often considered in the workup in this guide to the tremor and stiffness of Parkinson’s disease.
- Build confidence reading test results with this guide to reference ranges, flags, and next steps on a lab report.
Understand your lab results with BloodSense
ALS is diagnosed mainly through the clinical exam and nerve studies, but blood tests play a growing role, from muscle enzymes that help rule out other conditions to neurofilament light chain, a marker of nerve damage now used to support diagnosis and track the disease. Whenever you receive results, seeing where each value sits against its reference range makes them far easier to understand and discuss with your care team. BloodSense translates a full lab report into plain language, showing what each marker means and helping you follow changes over time instead of decoding one line at a time.
