ALS (Amyotrophic Lateral Sclerosis)

Overview

Amyotrophic lateral sclerosis (ALS), often called Lou Gehrig's disease, is a progressive neurological condition that gradually destroys the motor neurons, the nerve cells that carry signals from the brain and spinal cord to the muscles. As these nerves die, the muscles they control weaken and shrink, leading to a steady loss of the ability to move, speak, swallow, and eventually breathe.

ALS affects voluntary muscle control but usually spares the senses, bladder and bowel control, and, in most people, thinking ability, although some people develop changes in thinking or behavior. The disease worsens over time and currently has no cure, but treatments and supportive care can ease symptoms, prolong life, and help people maintain independence and quality of life for as long as possible.

Symptoms

Symptoms usually begin subtly in one part of the body and gradually spread:

• Muscle weakness in a hand, arm, leg, or foot
• Tripping, dropping things, or difficulty with fine tasks like buttoning a shirt
• Muscle twitching and cramps
• Slurred speech or difficulty swallowing
• Muscle wasting (shrinking) over time
• Increasing trouble walking and, later, breathing

The progression and starting point vary from person to person. ALS is generally not painful in itself, although muscle problems and immobility can cause discomfort.

Causes

In most people the cause of ALS is unknown; these are called sporadic cases. A smaller portion, often referred to as familial ALS, run in families and are linked to inherited gene changes. Research suggests that a combination of genetic and environmental factors leads to the progressive death of motor neurons.

Several biological processes are thought to contribute, including abnormal protein buildup in nerve cells and damage to the cells' machinery. Importantly, ALS is not contagious, and for the great majority of people there is nothing they did to cause it.

Risk Factors

• Age, with most cases beginning between 40 and 70
• A family history of ALS or certain related conditions
• Specific inherited gene changes in familial cases
• Sex, with men slightly more often affected at younger ages

For most people with sporadic ALS, no clear risk factor can be identified.

Diagnosis

There is no single test for ALS, so diagnosis involves confirming the pattern of nerve and muscle problems and ruling out other conditions:

• Neurological examination: Repeated over time to document progressive weakness affecting both upper and lower motor neurons.
• Electromyography (EMG) and nerve conduction studies: To assess the electrical activity of muscles and nerves.
• MRI: To rule out other causes such as spinal cord compression.
• Blood and other tests: To exclude conditions that can mimic ALS, sometimes including genetic testing.

Treatment

There is no cure for ALS, but treatment can slow symptoms, ease discomfort, and support daily life:

• Medications: Certain drugs are approved to modestly slow the disease's progression, and others help with symptoms such as muscle cramps, stiffness, excess saliva, and emotional changes.
• Breathing support: Devices that assist breathing as respiratory muscles weaken.
• Therapies: Physical, occupational, and speech therapy to preserve function, mobility, and communication.
• Nutrition support: Strategies and, when needed, feeding assistance to maintain nutrition as swallowing becomes difficult.
• Multidisciplinary care: A team approach that also addresses comfort, equipment, and emotional support.

Prevention

Because the cause of most ALS is unknown, there is no proven way to prevent it. Care instead focuses on early diagnosis and ongoing support:

• Seek evaluation promptly for unexplained, progressive muscle weakness
• Engage with a specialized ALS care team to access treatments and supportive services early
• For families with inherited ALS, genetic counseling can help with understanding risk

When to See a Doctor

See a doctor if you notice unexplained, progressive muscle weakness, frequent tripping, difficulty with fine hand movements, persistent muscle twitching, or changes in speech or swallowing. Early evaluation helps clarify the cause and connect you with care. Seek urgent care if you develop:

• Sudden difficulty breathing or shortness of breath
• Choking or an inability to swallow safely

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS). Amyotrophic Lateral Sclerosis (ALS).
2. Mayo Clinic. Amyotrophic lateral sclerosis (ALS).
3. ALS Association. Understanding ALS.
4. MedlinePlus, U.S. National Library of Medicine. Amyotrophic lateral sclerosis.