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ALS Overview

What is ALS?

Amyotrophic lateral sclerosis (ALS), also known as Motor Neuron Disease (MND), Lou Gehrig's Disease, and Charcot's disease, is a progressive neurodegenerative disease that attacks motor neurons in the brain and spinal cord. This results in the wasting away of muscle, loss of movement, and eventual paralysis.
Roughly 1 in 400 people will develop ALS in their lifetime, and there are an estimated 30,000 people living with ALS in the U.S. at any given time. We are still learning much about what causes ALS. About 85% of all ALS cases are sporadic with no known history of the disease in a family. The remaining 15% of cases of ALS are familial (inherited) ALS. ALS affects people of all races, ages, and genders.
Video: What is ALS?
There are currently no treatments to stop or reverse ALS progression, but researchers at the ALS Therapy Development Institute (ALS TDI) and around the world are working to change this.

ALS Symptoms

The first symptoms of ALS can vary, but early signs and symptoms may include:
  • muscle cramps and muscle twitching
  • weakness in hands, legs, feet or ankles
  • difficulty speaking or swallowing
These symptoms will continue to progress, eventually causing paralysis. The senses, including hearing, sight, smell, taste, and touch, are not affected by ALS. In most cases of ALS, memory and thinking are not affected.
ALS is not experienced in the same way among all those diagnosed. The manner and speed at which the disease moves throughout a person's body can vary greatly. Most people live about 3-5 years after experiencing their ALS symptoms, with one in ten people surviving for at least 10 years. The variable rate of disease progression makes prognosis difficult to predict and therapies challenging to develop.

Is there a cure for ALS?

Currently, there are no effective cures or treatments to stop ALS disease progression. ALS is a complex disease that varies from person to person. Far more research is necessary to discover effective treatments for each person living with ALS. That's why researchers at the ALS Therapy Development Institute (ALS TDI) are working hard each day to find ALS treatments. We aim to do this by identifying, testing, and developing promising new treatments and learning more about ALS through our ALS Research Collaborative (ARC).
What causes ALS?
Amyotrophic lateral sclerosis, ALS, is caused by progressive deterioration and death of motor neurons, leading to muscle weakness and paralysis.

Familial ALS

Fifteen percent of cases are known as familial ALS, in which a specific genetic mutation is inherited and passed down from generation to generation. Over 40 ALS-related genes have now been identified[1]. The most common known genetic mutation in ALS is the C9orf72 gene, which accounts for approximately 30 to 40 percent of all familial ALS cases [1]. Mutations in the SOD1 gene make up around 20 percent of familial ALS, and TARDBP and FUS gene mutations each account for about 5 percent of familial cases.

Sporadic ALS

The remaining 85 percent of cases are known as sporadic ALS, meaning there is no known history of the disease in a family. There are many theories outlining potential causes of ALS including oxidative stress, mitochondrial dysfunction, immune system over activity, glutamate toxicity and toxic exposures. Studies have shown that those who have served in the military are more likely to develop ALS than the general population [2], [3]. It is important to note that clinically, familial ALS and sporadic ALS appear to be indistinguishable from one another.

Who gets ALS?

ALS can affect anyone of any age, gender or race.
However, for the most part, ALS affects people between the ages of 40 and 70. ALS appears to affect men at a higher rate than women below the age of 65. Over the age of 70, ALS evidence has shown that ALS affects men and women at the same rate. According to recent research, ALS appears to be more common in white populations than in African American, Asian, or Hispanic populations [4] [5].

How is ALS Diagnosed?

There is no single diagnostic tool for ALS. The El Escorial criteria is commonly used to aid diagnosis, which requires the following:
  • Evidence of lower motor neuron (LMN) degeneration by clinical, electrophysiological or neuropathologic examination.
  • Evidence of upper motor neuron (UMN) degeneration by clinical examination.
  • Progressive spread of symptoms or signs within a region or to other regions, as determined by history or examination.
A series of clinical procedures may also be conducted to rule out neurological conditions whose symptoms closely resemble ALS. This means the ALS diagnostic process includes eliminating the possibility of many other diseases, including infections like Lyme disease and other neurological disorders such as multifocal motor neuropathy, before making a final diagnosis. For this reason, diagnosis can take as long as 12 to 14 months.
Throughout the diagnostic process, people may receive a diagnosis of suspected, possible, probable, or definite ALS. These designations depend on which parts of the body are affected by the disease. Without a definite diagnosis, people with possible or probable ALS nevertheless remain eligible to participate in a growing number of clinical trials evaluating emerging treatments for the disease. For a full list of ALS studies, visit our clinical trials page.
Some of the procedures a person may undergo on their way to an ALS diagnosis may include:
  • Genetic testing: When a familial case of ALS (fALS) is suspected, genetic testing might also be recommended. Commercially available tests can identify dozens of ALS-related genes. People that undergo genetic testing are typically provided genetic counseling, during which they learn how to interpret results.
  • Electromyography and nerve conduction studies: These tests enable clinicians to d whether motor nerves are plugged into the muscles and are working properly. Nerve conduction studies (NCS) test whether the motor nerves can send signals of sufficient strength to enable movement of the muscles. Electromyography (EMG) tests measure the ability of these muscles to trigger contraction in response to these signals. These tests help rule out certain other disorders that resemble the early symptoms of ALS.
  • Muscle Biopsy: Clinicians may also recommend a biopsy to further investigate affected muscles. Examination of muscle tissue under a microscope can help rule out certain muscle diseases.
  • Magnetic Resonance Imaging (MRI): MRI enables clinicians to examine organs and tissues including the brain and spinal cord. An MRI can help rule out a number of conditions including brain tumors, multiple sclerosis, and certain disorders of the spinal cord.
  • Other tests: These include blood, urine tests, and spinal taps. However, researchers hope to expedite the diagnostic process by developing tools that directly indicate whether a person has the disease.
Emerging tools
A growing number of researchers suspect that MRI could indicate whether a person has ALS rather than just eliminate other diseases. Researchers hope certain biomarkers can be used to identify people who are at high risk of developing ALS before they show symptoms.
Meanwhile, other scientists are developing a new method called electrical impedance myography (EIM) to diagnose ALS. This test helps identify changes in affected muscles, including atrophy. Scientists hope that this tool might also predict the spread of ALS and aid in the development of treatments for the disease.

What is the Prognosis of ALS?

Most people with ALS have a life expectancy of about 3-5 years after experiencing their first ALS Symptoms. At least one in ten people live more than 10 years following their diagnosis. This variable rate of progression makes predicting prognosis difficult. Clinicians instead rely on regular follow-up visits to monitor people with ALS to manage their disease.

Early Signs of ALS

Most people's early ALS symptoms include muscle cramps, spasms, or twitching (fasciculations) in one of their arms or legs. Other signs include weakness in the hands and feet or loss of balance. This form of the disease is called limb-onset ALS.
About 25 percent of people with ALS first have trouble talking clearly and begin to experience slurred speech. This form of the disease is called bulbar-onset ALS.

Monitoring ALS

After receiving a diagnosis, people with ALS often schedule regular clinic visits every 3-4 months. During these visits, patients are monitored for changes in their functional abilities and ALS symptoms. Commonly used tests for monitoring ALS include:
  • Spirometry: This is a test that measures lung function. Breathing abilities are typically estimated based on the maximum amount of air that can be blown out either slowly (slow vital capacity - SVC) or quickly (forced vital capacity - FVC).
  • ALS Functional Rating Scale-Revised (ALSFRS-R): The ALSFRS-R is a questionnaire that measures changes in a person's abilities, including breathing, speaking, sleeping, swallowing, and walking. The score is based on answers to 12 questions using a 48-point scale. Individuals with ALS can track their disease at home using the ALSFRS-R scale, there are several websites that offer that service free of charge, such as PatientsLikeMe.
  • ALS Research Collaborative (ARC): Through the ALS Research Collaborative (ARC), researchers at ALS TDI partner with people with ALS around the world to share and gather data on medical histories, family histories, genetics, biomarkers, and patient cell biology to better understand the disease. Participants are provided with a secure online portal where their data is located and easily accessible. They can track their own disease progression and follow how various interventions impact their symptoms and progression.
  • Clinic Visits: Following clinic visits, individuals with ALS should consider asking for access to the “data” obtained during the visit, such as the doctor's recorded ALSFRS-R and SVC or FVC scores. This information is used as enrollment criteria for most clinical trials. Having it on hand can allow people to quickly determine if they qualify for participation in a trial.

Middle Stages of ALS

As the disease spreads, many muscles weaken and start to stiffen. Range of motion exercises will likely be recommended by physical therapists to help keep muscles loose and prevent the formation of contractures and muscle pain.
A person with ALS's breathing may become affected. A BiPAP machine or a phrenic pacer might be suggested, particularly to help improve sleeping. A feeding tube might be recommended to help meet nutritional needs. Medications might be also recommended to help control pseudobulbar affect (uncontrolled laughing or crying) or to help reduce muscle spasms.
People with bulbar-onset ALS often work with a speech therapist to keep their ability to speak for longer. Those with limb-onset ALS may rely on a cane, walker, or wheelchair due to difficulties walking and maintaining balance.

ALS and Frontotemporal Dementia

In most cases of ALS, cognitive function is not affected. However, over the past 10 years, there has been an increasing interest in investigating the overlap of ALS with Frontotemporal Dementia (FTD), another neurological disease characterized by a decline in cognitive function. It is believed that up to a third of those diagnosed with ALS may be affected by cognitive issues.

Late Stages of ALS

As ALS progresses and a person's muscles become paralyzed, they may lose the ability to move and speak. Many people with ALS may require a wheelchair to get around. Some may communicate through assistive devices like an eye-tracking device or a letter board. Some people with ALS choose to undergo a tracheostomy, a procedure in which a tube is surgically inserted into the throat, to help them breathe. People with late-stage ALS are often cared for at home or in hospice.
Treatments for ALS

ALS Medications

There are currently no effective cures for ALS or treatments to stop disease progression, but scientists are working hard to develop therapies for this disease. There are currently only four treatments approved by the FDA in the United States. They are riluzole (marketed as Rilutek or Tiglutik), edaravone (marketed as Radicava), a combination of sodium phenylbutyrate and taurursodiol (marketed as Relyvrio), and tofersen (marketed as Qalsody).
  • Riluzole was approved for treating ALS in the 1990s. Its effects are modest, extending life by about two to three months.
  • In May 2017, edaravone was approved by the FDA. Clinical trials of edaravone showed that those who began getting infusions of the medication early on in their disease had the greatest potential to maintain muscle function.
  • Relyvrio, a combination of two drugs – sodium phenylbutyrate and taurursodiol – was approved by the FDA in 2022. The drug, also known as Albrioza in Canada, was shown to slow the loss of physical function in people with ALS in a phase 2 trial in the US. While Relyvrio is still currently approved for ALS in the US as of April, 2024, the drug's sponsor, Amylyx, has announced they will voluntarily remove it from market after its Phase 3 trial did not meet primary or secondary endpoints.
  • Tofersen, sold under the brand name Qalsody, is an antisense oligonucleotide (ASO), a short strand of nucleic acids that can enter a cell and bind with mRNA strands, in this case effectively “turning down” a gene and disrupting the production of a specific protein. Although the phase III trial with 108 participants did not meet its primary functional endpoint, this drug was approved for use by people with SOD1 ALS in early 2023 based on reductions in levels of neurofilament light chain (NfL), a blood-based biomarker that is related to neurodegeneration, in participants on active drug.
While none of these treatments have been shown to halt the progression of ALS, some people who take one or a combination of two or three may experience a positive impact on their progression. Riluzole, edaravone, Relyvrio, and Qalsody are available today. People with ALS are encouraged to speak with their doctor to determine if these treatments are right for them.

ALS Clinics

ALS is a complex, multi-system disease. A growing number of ALS clinics are deploying multidisciplinary teams to care for and meet the physical, emotional, and nutritional needs of people with ALS. These palliative care teams include physical, respiratory, speech, and occupational therapists to help people with ALS breathe easier, keep moving, and stay connected.

ALS Clinical Trials

Today, there are dozens of potential treatments in clinical trials that are enrolling people with ALS. You can visit our ALS Treatments and Drugs page to read more about potential therapies for ALS. For more information on enrollment and inclusion criteria for clinical trials, visit our clinical trials page.