Various movement disorders impact how the body manages motion, coordination, and muscle function. Some, such as tremor or dystonia, feature excessive movement, while others, like Parkinson’s disease, involve reduced movement. This article highlights one of the most severe conditions: Amyotrophic Lateral Sclerosis (ALS), also called Lou Gehrig’s disease.
Amyotrophic Lateral Sclerosis (ALS), commonly known as Lou Gehrig’s disease, is a progressive and ultimately fatal neurological disorder that attacks the nerve cells responsible for controlling voluntary movement. These nerve cells, called motor neurons, act as communication lines between the brain, spinal cord, and muscles. In ALS, those connections gradually break down. As motor neurons die, the brain can no longer send signals to the muscles that allow us to walk, talk, swallow, breathe, or even hold our heads up. According to the ALS Association, “What differs most for every person is how fast and in what order symptoms and progression occur. And, while the average survival time is three years, about 20% of people with ALS live five years, 10% survive 10 years, and 5% live 20 years or longer.” As ALS progresses, more neurons stop functioning, and the muscles they control can no longer receive signals from the brain. This effect causes increasing weakness, loss of coordination, and eventually a complete paralysis of those muscle groups occurs. This process spreads throughout the body over time, affecting normal bodily functions such as walking, hand strength, speech, swallowing, and, finally, the respiratory muscles that allow a person to breathe, eventually making the paralysis lethal to the patient. Because this degeneration continues month after month, most people experience significant disability within just a few years of their first symptoms.
Although ALS has been recognized for more than a century, it remains one of the most challenging conditions in neurology. While it can strike adults of almost any age, the disease most commonly affects people between the ages of 50 and 70. Once symptoms begin, the disease tends to steadily progress, leading to a significant decline in the body’s functions and disability within a few years. According to the National Institute of Neurological Disorders and Stroke, “Men are slightly more likely to develop ALS than women. But at older ages, men and women are equally likely to be diagnosed with ALS.” When it comes to race, “White people, particularly non-Hispanic White people, are most likely to develop ALS, but it affects people of all races and ethnicities.”
Lou Gehrig
Lou Gehrig’s disease is named after Lou Gehrig, the New York Yankees’ first baseman, who was diagnosed with ALS in 1939. Gehrig was one of the most famous athletes in America, known as “The Iron Horse” for his incredible durability playing in 2,130 consecutive games, a record that stood for decades in Major League Baseball.
When he began to lose strength, coordination, and stamina, doctors eventually diagnosed him with Amyotrophic Lateral Sclerosis (ALS), a condition that was not widely known by the public. His emotional retirement speech on July 4, 1939, in which he called himself “the luckiest man on the face of the earth,” brought massive attention to the disease.
Because his diagnosis was so widely publicized, ALS became commonly referred to as Lou Gehrig’s disease, especially in the United States. The name honors his legacy and reflects the role his story played in raising awareness of the condition early on.
How ALS Affects the Body
The primary feature of ALS is progressive muscle weakness. Early signs often appear in the hands or feet: difficulty buttoning a shirt, holding objects, walking without tripping, or writing with the same fluidity as before. Some people first notice changes in their voice, slurred speech, hoarseness, or trouble projecting words clearly.
These changes occur because ALS destroys both upper motor neurons (which originate in the brain) and lower motor neurons (which extend into the muscles). Each type of neuron plays a different role, so symptoms reflect damage to both upper motor neuron (muscle stiffness, exaggerated reflexes, spasms, slowed movement) and lower motor neuron (muscle wasting or atrophy, muscle twitching or fasciculations, weakness, and loss of muscle bulk and tone).
Over time, muscle weakness spreads throughout the body. People lose the ability to perform tasks that require fine motor skills, then gross motor skills like walking or lifting. As the muscles responsible for swallowing weaken, eating becomes difficult, raising the risk of choking or malnutrition. Speech becomes softer and more slurred, eventually leading many to rely on assistive communication devices.
The most life-threatening symptom of ALS occurs when the respiratory muscles, including the diaphragm, can no longer function. Without the ability to breathe effectively on their own, many people require non-invasive ventilation and, later, more advanced breathing support.
Despite these physical declines, it’s important to note that thinking and awareness often remain intact. Many individuals with ALS stay mentally sharp, fully aware of each stage of their illness. However, up to 50% may develop mild changes in cognition or behavior, and about 10–15% develop frontotemporal dementia, a related neurological condition that affects decision-making and personality.
What Causes ALS?
The exact cause of ALS remains uncertain, but research has uncovered several key contributors, including Genetic Factors. About 5–10% of ALS cases are familial, meaning they run in families. The most common genetic mutation is in the C9orf72 gene, while others include SOD1, TARDBP, and FUS. These mutations disrupt normal cell function and contribute to motor neuron death. In Sporadic ALS, around 90% of the cases occur randomly with no clear family history and arise from a combination of age-related changes, environmental factors such as exposure to pesticides, heavy metals, military service, and head trauma. Cellular stress and immune dysregulation.
One of the biggest breakthroughs in recent years is the idea that ALS may involve the immune system reacting abnormally to certain proteins, especially in people with C9orf72 mutations. This has opened the door to exploring ALS as, at least partly, an autoimmune-linked neurodegenerative disease.
How ALS Is Diagnosed
There is no single test to confirm ALS. Doctors rely on a combination of neurological exams, electromyography (EMG), nerve conduction studies, MRI scans, and blood tests to rule out mimicking conditions. Because symptoms start subtly and progress gradually, diagnosis is often delayed by months or even years. There is no single test that can definitely diagnose ALS. A doctor will conduct a physical exam and review the person’s full medical history. A neurologic examination will test reflexes, muscle strength, and other responses. These tests should be performed at regular intervals to assess whether symptoms are getting worse over time.
According to the National Institute of Neurological Disorders and Stroke:
“A doctor may conduct muscle and imaging tests to rule out other disorders. This can help support an ALS diagnosis. One test is magnetic resonance imaging (MRI), which uses a magnetic field and radio waves to produce detailed images of the brain and spinal cord. Another is electromyography (EMG), which evaluates how well nerves and muscles are functioning. An EMG can include: A nerve conduction study (NCS), which measures the electrical activity of nerves and muscles by assessing the nerve’s ability to send a signal along the nerve or to the muscle.A needle exam, which is a recording technique that detects electrical activity in muscle fibers using a needle electrode. Other tests can rule out the possibility of other disorders. They can include: Muscle biopsy, blood and urine tests, or a spinal tap (lumbar puncture) to test the person’s cerebrospinal fluid (CSF).”
Current Treatments and What They Do
While there is no cure for ALS, several treatments can slow the disease or help manage symptoms. Medications include Riluzole, which “modestly” extends survival, Edaravone (Radicava), which reduces oxidative stress, and may slow decline in early cases. AMX0035 (Relyvrio) is a medication designed to protect nerve cells, and Tofersen is a gene-targeted therapy for SOD1 mutation carriers.
Supportive Therapies currently include physical and occupational therapy, speech therapy, and communication devices, nutritional support, including feeding tubes when needed, and non-invasive ventilation for breathing support. Although these treatments don’t stop ALS, they significantly improve quality of life and can extend survival.
The Future of ALS Research
ALS research is accelerating rapidly, thanks to advances in genetics, cell biology, and immunology. Scientists are now studying gene-editing strategies like CRISPR, immune-modulating therapies, stem cell-based treatments, early diagnostic biomarkers, including blood tests for cell-free DNA, and therapies tailored to specific genetic mutations. The discovery of immune system involvement in ALS, particularly in the C9orf72 subtype, may be one of the most promising avenues for future therapies.
For more information about patient support, clinics, therapies, and other supportive care, go to the ALS Association website. To join the CDC’s ALS Registry click here
The Differences between ALS and Parkinson’s
ALS and Parkinson’s disease are both movement-related neurological disorders, but they affect the body in very different ways. ALS destroys the motor neurons in the brain and spinal cord, causing progressive muscle weakness, wasting, difficulty speaking and swallowing, and eventually paralysis and breathing failure. Parkinson’s Disease, on the other hand, results from the loss of dopamine-producing cells in the brain, leading to tremor, stiffness, slowed movement, and balance problems without muscle wasting. ALS typically progresses much faster, often within a few years, while Parkinson’s usually advances slowly over decades. A person’s thought process is usually preserved in ALS except in cases of frontotemporal dementia, whereas Parkinson’s may lead to cognitive changes later in the disease. Treatments for ALS can slow progression but do not stop it, while Parkinson’s has several effective therapies, including levodopa and deep brain stimulation, that significantly improve daily function.
A new study in Nature suggests an autoimmune component to ALS that could be targeted as a new form of therapy. You can read more about it here.