ALS affects roughly 5,000 to 6,000 people in the United States at any given time

The ALS Association estimates that between 5,000 and 6,000 Americans are living with ALS right now. That number comes from research tracking how many people have the disease, how many new cases appear each year, and how long people typically survive after diagnosis. The figure is not exact—different studies using different methods produce slightly different counts—but this range represents the best current estimate.

About 300 to 400 new cases are diagnosed in the United States each month. That means roughly 3,600 to 4,800 Americans receive an ALS diagnosis every year. Because ALS is fatal and most people die within two to five years of diagnosis, the total number of living patients stays relatively stable even as new cases emerge constantly.

Worldwide, ALS is rarer. Globally, somewhere between 350,000 and 400,000 people are thought to have ALS at any moment, though exact numbers are harder to pin down because diagnosis and reporting vary widely by country.

Key Takeaways

  • Between 5,000 and 6,000 Americans currently have ALS, with roughly 3,600 to 4,800 new diagnoses each year.
  • ALS is more common in men than women, and risk increases with age, though the disease can strike at any age after 18.
  • About 90 percent of ALS cases appear to be sporadic (not inherited), while 10 percent run in families.
  • Survival time after diagnosis varies widely—some people live two years, others live ten or more—so prevalence numbers do not tell you what to expect individually.

Why the numbers vary depending on the source

Different organizations count ALS cases in different ways. The ALS Association uses data from the National ALS Registry, which collects information from neurology clinics, hospitals, and insurance records. Other researchers conduct population surveys or analyze death certificates. Each method catches slightly different groups of people, which is why you may see estimates ranging from 4,500 to 7,000 depending on the source and year.

The National ALS Registry, run by the Centers for Disease Control and Prevention (CDC), is the most systematic attempt to count cases. It began in 2010 and now includes data from thousands of patients. Even so, some people with ALS never see a neurologist or may be misdiagnosed, so the true number could be somewhat higher than the registry captures.

Who gets ALS: age, sex, and family history

ALS typically appears in people over age 40, and risk rises sharply after age 60. The average age at diagnosis is around 64. However, ALS can strike younger people—cases in people in their 20s and 30s do occur, though they are uncommon.

Men develop ALS more often than women. Studies show roughly 1.5 to 2 men diagnosed for every woman diagnosed, though the gap has narrowed slightly in recent years and the reason for the difference remains unclear.

About 90 percent of ALS cases are sporadic, meaning they appear to arise randomly with no family history. The remaining 10 percent are familial ALS (fALS), inherited from a parent who carries a gene mutation. If one parent has familial ALS, each child has a 50 percent chance of inheriting the mutation. Not everyone who inherits the mutation develops the disease, but the risk is high.

How ALS prevalence compares to other neurological diseases

ALS is rare compared to Parkinson's disease, which affects roughly 1 million Americans, or Alzheimer's disease, which affects about 6 million. But ALS is more common than some other motor neuron diseases. Primary lateral sclerosis and progressive muscular atrophy, which are related conditions, each affect far fewer people.

The rarity of ALS means most primary care doctors see only a handful of cases in their entire career. That is one reason diagnosis often takes months—the disease is uncommon enough that it may not be the first thing a doctor considers when a patient reports weakness or muscle loss.

What prevalence numbers do and do not tell you

Knowing that 5,000 to 6,000 Americans have ALS does not tell you how long you or anyone else will live after diagnosis. Survival varies enormously. Some people die within a year of diagnosis, while others live ten years or longer. The average is often cited as two to five years, but that average masks huge individual variation.

Prevalence also does not predict your own risk. Even though ALS is more common in men and older adults, a young woman can develop it. Even though 90 percent of cases are sporadic, having no family history does not may provide you will not get ALS.

The numbers do show that ALS, while rare, is not so rare that nothing is known about it. Thousands of people are living with the disease right now, which means research is ongoing, treatments are being tested, and support systems exist. The prevalence is high enough to matter and low enough to explain why many people have never heard of ALS until they or someone close to them is diagnosed.

How prevalence data is collected and why it matters

The CDC's National ALS Registry collects data from participating neurology clinics and uses Medicare and Veterans Affairs records to identify people with ALS. Patients can also register themselves through the registry website. This approach captures most people who have been formally diagnosed, but it misses people who have not yet seen a neurologist or who live in areas without participating clinics.

Researchers use prevalence data to understand whether ALS is becoming more common, whether certain groups are at higher risk, and where to focus prevention and treatment efforts. Tracking new cases each year also helps predict how many people will need care services and how much research funding may be needed.

Frequently Asked Questions

Is ALS becoming more common?

Some studies suggest ALS incidence (new cases per year) may be rising slightly, but it is unclear whether the disease is truly becoming more common or whether better diagnosis and reporting are catching more cases. The trend varies by age group and region, so there is no simple yes or no answer.

Why are men more likely to get ALS than women?

The reason for the male predominance in ALS is not fully understood. Researchers have proposed genetic, hormonal, and environmental explanations, but none has been proven. The gap between men and women appears to be narrowing over time, which suggests the difference may not be purely biological.

If my parent has ALS, will I definitely get it?

If your parent has familial ALS and you inherited the mutation, your risk is high but not certain. Some people who carry the mutation never develop symptoms, even into old age. Genetic counseling can help you understand your individual risk based on which gene is involved and your family's pattern of disease.

How do doctors know how many people have ALS if it is so rare?

The CDC's National ALS Registry tracks cases reported by neurology clinics and uses insurance and Veterans Affairs records to identify people with ALS. Researchers also conduct population surveys in specific regions. These methods do not capture every case, but they provide a reliable estimate of how common the disease is.

Does the number of ALS cases include people who have died from it?

No. Prevalence counts only people living with ALS at a specific point in time. Incidence counts new diagnoses each year. Mortality counts deaths. These are three different measures, and each tells a different part of the story about how common ALS is and how it affects populations.