Learn About ALS Prevention and Current Research

Understanding ALS: What You Need to Know

Amyotrophic lateral sclerosis, commonly known as ALS, is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. These nerve cells, called motor neurons, control the voluntary muscles throughout your body. When motor neurons break down, they stop sending signals to muscles, causing them to weaken and eventually stop working. This guide provides information about what ALS is, current prevention research, and the latest scientific developments in understanding this disease.

ALS was first described in 1869 by French neurologist Jean-Martin Charcot, who called it "amyotrophic lateral sclerosis." The name describes what happens in the disease: "amyotrophic" refers to the wasting of muscles, "lateral" indicates where damage occurs in the spinal cord, and "sclerosis" means scarring or hardening of that area. Today, researchers understand ALS much better, though many questions remain about why it develops and how to prevent it.

The disease typically appears in people aged 40 to 70, though it can occur at any age. According to the ALS Association, approximately 5,000 people in the United States are newly diagnosed with ALS each year, and about 16,000 Americans are living with the disease at any given time. Worldwide, ALS affects roughly 2 out of every 100,000 people annually. The disease progresses at different rates for different people, but it is ultimately fatal.

ALS exists in two main forms: sporadic ALS, which accounts for about 90 percent of cases and appears to develop without a clear family history, and familial ALS, which accounts for about 10 percent of cases and runs in families with a known genetic link. Understanding these types helps researchers investigate different potential causes and prevention strategies. Early signs of ALS often include muscle twitching, weakness in the legs or arms, slurred speech, and difficulty swallowing, though symptoms vary among individuals.

Practical takeaway: Learning to recognize early signs of ALS—such as unexplained muscle weakness, twitching, or difficulty with physical activities—can lead to earlier medical evaluation and diagnosis. If you notice persistent muscle weakness or other concerning symptoms, speak with a healthcare provider about getting a proper evaluation.

Genetic Risk Factors and Family History

Research has identified numerous genetic mutations associated with ALS development. The most commonly studied gene is SOD1 (superoxide dismutase 1), which accounts for about 2 percent of all ALS cases. Other significant genes include C9orf72, FUS, and TARDBP, each contributing to disease risk in different populations. Scientists have identified over 30 genes linked to ALS, and new discoveries continue regularly. Understanding these genetic factors helps researchers develop targeted prevention and treatment strategies.

For people with familial ALS, having a parent, sibling, or child with the disease increases the likelihood of developing ALS themselves. If one parent carries an ALS-related genetic mutation, their children have a 50 percent chance of inheriting that mutation. However, inheriting a mutation does not guarantee that a person will develop ALS—this is called incomplete penetrance. Some people carry disease-related mutations but never show symptoms, suggesting that other factors influence whether the disease actually develops.

Genetic testing can reveal whether someone carries known ALS-associated mutations. This information may be valuable for family members of people diagnosed with ALS. Learning your genetic status can inform decisions about lifestyle changes, medical monitoring, and participation in research studies. Genetic counseling before and after testing can help individuals understand what test results mean for their health and family planning.

Recent research has focused on understanding why some people with genetic mutations develop ALS while others do not. This area of study, called epigenetics, examines how environmental factors and lifestyle choices may activate or silence genes. For example, researchers are investigating whether factors like smoking, head injury, or exposure to environmental toxins might trigger disease in genetically susceptible individuals. This knowledge may eventually lead to prevention strategies targeting modifiable risk factors in high-risk populations.

Practical takeaway: If ALS runs in your family, speaking with a genetic counselor about your risk and what genetic testing might reveal can help you make informed decisions about your health. Family members of people with ALS can also participate in research studies designed to understand disease development and test potential preventive approaches.

Environmental and Lifestyle Risk Factors

Scientists have identified several environmental and lifestyle factors that may increase ALS risk, though research is still ongoing to confirm these connections. Smoking cigarettes has been consistently linked to increased ALS risk in multiple studies. A large study published in the journal Neurology found that current smokers had approximately 60 percent higher risk of developing ALS compared to people who never smoked. This association appears particularly strong in men and increases with duration and intensity of smoking.

Military service has also been associated with higher ALS rates. Veterans have approximately twice the risk of developing ALS compared to non-military populations. Researchers believe this increased risk may relate to exposures during service, such as lead ammunition, pesticide exposure during training or deployment, or traumatic brain injury. The U.S. Department of Veterans Affairs recognizes ALS as a service-connected condition, acknowledging this established connection.

Head injury and traumatic brain injury have been studied as potential ALS risk factors, with some research suggesting that significant head trauma may increase disease risk. Several studies have found increased ALS rates among professional athletes and military personnel who experience repeated head impacts. However, the strength of this association remains debated, and more research is underway to clarify the relationship.

Other factors under investigation include occupational exposures to heavy metals like lead and mercury, pesticide exposure, physical exertion or occupational demands, and exposure to certain viral infections. Some research suggests that intense physical activity or occupational demands may be associated with ALS, possibly by accelerating disease progression in genetically susceptible individuals. Environmental toxins including pesticides, fertilizers, and industrial chemicals have been examined in various geographic regions where ALS rates appear elevated, though definitive causal relationships remain unclear.

Practical takeaway: While you cannot change some risk factors, quitting smoking and avoiding head injuries represent modifiable behaviors that research suggests may reduce ALS risk. Minimizing exposure to environmental toxins through protective equipment at work and staying informed about environmental hazards in your area may also be beneficial.

Current Research Into Prevention and Treatment

Scientists worldwide are pursuing multiple research approaches aimed at understanding ALS development and identifying ways to prevent or slow disease progression. One major research direction involves studying cellular mechanisms—how motor neurons die and what triggers this process. Researchers have discovered that ALS involves accumulation of abnormal proteins in motor neurons, oxidative stress that damages cells, inflammation, and disruption of normal cellular processes. Understanding these mechanisms opens pathways to develop interventions targeting specific disease processes.

Several drugs have shown promise in slowing ALS progression. Riluzole, approved by the FDA in 1995, extends survival by a few months on average. More recently, edaravone, approved in 2017, has shown modest benefits in slowing decline in certain ALS patients. Sodium phenylbutyrate combined with ursodoxicoltaurine, marketed as Relyvrio, received FDA approval in 2023 and showed about 25 percent slowing of decline in clinical trials. While these medications provide only partial benefit, they represent progress and inform researchers about disease mechanisms.

Emerging research focuses on gene therapy and antisense oligonucleotide therapies, which work by modifying how genes are expressed or reducing production of harmful proteins. Several therapies targeting specific genetic forms of ALS are in clinical trials. For example, antisense therapies targeting C9orf72 mutations and SOD1 mutations are being tested. These targeted approaches show particular promise because they address specific genetic causes in particular patient populations.

Researchers are also investigating whether certain compounds might prevent or delay ALS onset in people who carry genetic risk mutations but have not yet developed symptoms. Clinical trials are underway in asymptomatic gene carriers, testing whether early intervention might prevent or delay symptom appearance. Lifestyle interventions including exercise programs, diet modifications, and cognitive engagement are being studied to determine whether they might slow progression or support better outcomes. Additionally, researchers continue examining whether controlling other health conditions like diabetes or hypertension might influence ALS risk or progression.

Practical takeaway: Staying informed about clinical trials and emerging treatments allows you or your family members to discuss potential participation with healthcare providers. The NIH Clinical Trials database and organizations