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What You Should Know About ALS, Also Known as Lou Gehrig’s Disease

Medically reviewed by Carmen Pope, BPharm. Last updated on May 4, 2025.

By Brian Lin, PhD, Research Portfolio Director at the Muscular Dystrophy Association (MDA) HealthDay Reporter

SATURDAY, May 3, 2025 — Amyotrophic lateral sclerosis (ALS) – known as Lou Gehrig’s Disease based on the iconic 1930s New York Yankee baseball player – is a progressive neurodegenerative disease that affects thousands of Americans every year. ALS remains one of the most complex and challenging disorders known to science.

May is ALS Awareness Month, making it an ideal time to take a closer look at this condition — who it affects, how it progresses and what efforts are underway to advance care, accelerate research and provide support to families across the country.

What is ALS?

ALS, according to the National Institutes of Health (NIH), is a disease that targets the motor neurons, nerve cells in the brain and spinal cord that coordinate voluntary muscle movement. As these neurons degenerate and die, the signals from the brain are unable to transmit messages to muscles, leading to muscle atrophy, weakness, paralysis and ultimately, respiratory failure.

People with ALS lose the ability to walk, speak, eat and breathe independently, though most ALS patients retain their cognitive abilities. ALS is a progressive disease and most people live two to five years after their diagnosis.

Its clinical presentation varies widely, and its progression can differ widely from person to person, making every individual’s experience with ALS unique. With expanding treatment options, there is growing hope for improving both quality of life and survival.

Who gets ALS?

Anyone can get ALS, according to the U.S. Centers for Disease Control and Prevention (CDC), though most people are diagnosed between the ages of 40 and 70. In the United States, about 5,000 new cases are diagnosed each year, and an estimated 30,000 people are living with the disease.

There are two main types of ALS:

• Sporadic ALS makes up about 90% of cases and happens without any known family history of the disease. However, current research has shown that around 10% to 15% of these cases may involve genetic changes.

• Familial ALS, the inherited form of the disease, accounts for about 5% to 10% of cases. It’s usually caused by specific genetic mutations.

Some groups are more likely to develop ALS than others. Military veterans are about twice as likely to develop ALS, regardless of their deployment history or branch service, according to the National Institute of Neurological Disorders and Stroke.

Possible reasons include environmental exposures, physical injuries or intense physical activity, though more research is needed to understand it fully.

Similarly, fire fighters are nearly twice as likely to be diagnosed with ALS, potentially due to on-the-job exposure to dangerous chemicals, smoke and other toxic materials. These trends highlight the urgent need for further research into occupational and environmental risk factors and the importance of expanding access to expert care for those who serve and protect communities.

While there is still much to learn, the U.S. Department of Veteran Affairs recognizes ALS as a service-related condition, meaning veterans with ALS are eligible for a wide range of benefits, including comprehensive health care services, disability compensation, adaptive equipment and more. The ALS Veteran Handbook has more specific information.

What are the symptoms?

ALS often begins subtly, and symptoms vary from person to person. Early signs can clinically manifest in a variety of ways and can be categorized into subtypes based on site of onset and motor neuron involvement. The Living with ALS report lists some of the most common symptoms, including:

• Muscle cramps or twitching (fasciculations), typically beginning in one limb (limb-onset) or affecting speech and swallowing (bulbar-onset)

• Spasticity (stiffness) and hyperreflexia (overactive reflexes) resulting from upper motor neuron degeneration

• Muscle wasting, weakness (particularly in the hands, legs or feet) and visible cramps or twitching from lower motor neuron degeneration

• Bulbar involvement (caused by damaged nerve cells in part of the brain), showing up as difficulty speaking (dysarthria), difficulty swallowing (dysphagia), tongue atrophy, and drooling (sialorrhea), with sudden, uncontrollable changes in emotions (pseudobulbar affect) often present.

• Tripping or stumbling

• Difficulty with fine motor tasks, such as buttoning a shirt

Over time, these symptoms become more widespread. As motor neurons continue to die, people with ALS lose the ability to perform everyday activities and eventually require aid with breathing.

Respiratory symptoms may include dyspnea (breathless sensation) on exertion or at rest, orthopnea (shortness of breath while lying down), sleep-disordered breathing, and declining forced vital capacity, which is closely monitored as a marker of disease severity.

Although ALS predominantly affects motor neurons, up to 50% of patients experience cognitive or behavioral changes, and 10% to 15% develop frontotemporal dementia (FTD).

What causes ALS?

In most cases, the exact cause of ALS remains unknown, but genetics are believed to play a major role. In recent decades, researchers have identified nearly 50 genes associated with ALS, with the most common mutations occurring in the SOD1, C9orf72, TARDBP,and FUS genes, which disrupt normal nerve cell function.

In sporadic ALS, a complex mix of genetic susceptibility and environmental exposures is thought to be involved. Potential risk factors include exposure to certain toxins, heavy metals, viral infections, intense physical activity and traumatic brain injury.

More research is needed to fully understand these risks as genetics, age and other unknown variables may contribute to motor neuron degeneration.

How is ALS diagnosed?

Diagnosing ALS can be a lengthy and difficult process. Its symptoms overlap with other neurological disorders, and there is no single test that definitively confirms the diagnosis.

Doctors typically rely on a combination of tools, according to the Mayo Clinic, including:

• Detailed clinical history and genetic testing, particularly when familial ALS is suspected.

• Neurological examinations to identify telltale motor neuron signatures that distinguish healthy and damaged cells.

• Electromyography (EMG) and nerve conduction studies help to confirm hallmark patterns of motor nerve function (denervation and reinnervation).

• Cognitive and behavioral testing to assess for ALS-FTD (ALS-Frontotemporal Dementia) by evaluating executive function (decision-making), language abilities and behavioral changes.

ALS is also diagnosed by ruling out other potential causes of motor neuron dysfunction, a process that may include:

• MRI scans to rule out structural brain or spine abnormalities.

• Blood and urine tests to exclude other diseases.

Early diagnosis is crucial for accessing therapies, enrolling in clinical trials and building a comprehensive care plan.

What treatments are available?

While there’s no cure for ALS yet, several therapies approved by the U.S. Food and Drug Administration can help slow disease progression. A recent review in Frontiers of Neurology noted these therapies are available:

• Riluzole (Rilutek) – An oral medication that decreases cellular excitotoxicity caused by excess glutamate (a molecule released by nerve cells for signaling muscles).

• Edaravone (Radicava) – An antioxidant, administered intravenously, that can slow damage to motor neurons. In some individuals, edaravone has been shown to slow functional decline. An alternative form, RADICAVA ORS, is available in the United States but not in some other countries.

• Tofersen (Qalsody) – A medication that can be used to treat a specific genetic form of ALS caused by SOD1 mutations (SOD1-ALS). It received accelerated approval from the FDA in 2023, and is now part of an ongoing phase 3 trial.

ALS remains an active area of research with many therapies in clinical testing.

About 30 active interventional clinical trials in the United States are enrolling people with ALS to test potential therapies, according to clinicaltrials.gov. Worldwide, there are more than 120 active interventional trials.

In the United States, some ALS clinical trials are conducted through the HEALEY ALS Platform Trial, an innovative effort designed to accelerate development of treatments by evaluating multiple investigational therapies at the same time. To learn more about therapies under testing on the platform trial, visit the Healey ALS Platform Trial.

The state of ALS research

Despite extensive research, the exact causes of ALS remain unclear. But significant progress has been made to uncover genetic contributors, identify promising therapeutic targets and develop biomarkers that are critical for early diagnosis and intervention.

Some of the most exciting current developments in ALS research include:

• RNA-targeted therapies: Tofersen is being studied in the ongoing ATLAS trial for carriers of the SOD1 mutation who do not have symptoms. This drug, an antisense oligonucleotide (ASO), stops the mutated gene from producing toxic SOD1 proteins. These therapies have the potential to not only treat ALS but also prevent its onset in people who are genetically predisposed. The trial is expected to yield significant insights into the future of ALS treatment and prevention.

• Gene therapies: Gene therapy for ALS is advancing rapidly, with companies like Insmed and uniQure developing targeted treatments using AAV-based delivery systems. uniQure is conducting a phase 1/2 clinical trial of AMT-162, a therapy aimed at treating familial ALS caused by SOD1 mutations.

• Biomarkers: Neurofilament Light Chain (NfL) is gaining significant attention as a biomarker that correlates with disease progression and treatment response, as demonstrated in the Tofersen trial. These biomarkers may one day enable earlier diagnosis and personalized treatment strategies.

• Artificial Intelligence (AI): Researchers are increasingly applying machine learning algorithms to analyze genetic data and improve diagnostics. This AI-driven approach holds promise for identifying stronger therapeutic targets and developing personalized treatment paths.

• Coordinated Research Partnerships: AMP ALS and ALL ALS represent pivotal efforts to transform the ALS research landscape. By tackling critical challenges in ALS drug development, such as clinical trial efficiency, patient recruitment and data sharing, ALL ALS is working to speed discovery and approval of effective therapies. AMP ALS, a public-private partnership, accelerates research by fostering data sharing, collaboration and targeted therapies to deepen understanding of the disease. Learn more about these initiatives at AMP ALS and ALL ALS.

With multiple clinical trials now underway and more therapies entering the pipeline, researchers are moving ever closer to meaningful breakthroughs.

Living with ALS

An ALS diagnosis can be overwhelming, but many individuals continue to work, advocate, write and inspire long after their diagnosis.

Through resources like the MDA Care Center Network, the MDA Resource Center, and other national advocacy groups, families can find information, clinical guidance and emotional support.

Assistive technologies such as eye-tracking devices, speech-generating tools and power wheelchairs can help individuals maintain independence and connection to the world around them.

The road ahead

ALS is a devastating disease — but progress is being made. Thanks to decades of tireless research, advocacy and support from organizations like the Muscular Dystrophy Association, the world is closer than ever to earlier diagnoses, better treatments and a future where ALS is no longer a life-ending diagnosis — but a manageable and ultimately, curable condition.

MDA’s role in ALS care and support

Over the past 75 years, the Muscular Dystrophy Association (MDA) has invested more than $178 million in ALS research, driving major advances in disease understanding and directly supporting the development of treatments, including riluzole and tofersen.

The MDA also operates the nation’s largest network of multidisciplinary neuromuscular clinics, including 47 designated MDA/ALS Care Centers. These clinics bring together neurologists, physical therapists, respiratory therapists, speech-language pathologists and social workers to provide comprehensive, coordinated care under one roof.

Research has shown that multidisciplinary care leads to longer survival and improved patient outcomes. It also helps patients maintain independence longer and navigate the many physical and emotional challenges that ALS presents.

The MDA Resource Center is a source for support and answers to day-to-day questions. lifeline. Families can contact trained specialists by phone or email for personalized guidance on navigating a diagnosis, finding local services and connecting with clinical trials and community resources.

How you can help

This ALS Awareness Month, you can make a difference by:

• Learning more and sharing credible information

• Participating in an MDA fundraiser

• Donating to research-focused organizations like MDA

• Asking your legislators to support ALS care and drug access

• Letting someone living with ALS know they are seen and supported

Brian Lin, PhD, is a research portfolio director at the Muscular Dystrophy Association, where he oversees investment in ALS and neuromuscular disease research.

Disclaimer: Statistical data in medical articles provide general trends and do not pertain to individuals. Individual factors can vary greatly. Always seek personalized medical advice for individual healthcare decisions.

Posted May 2025

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