Multiple Sclerosis vs. ALS: Similarities and Differences

Written by Kimberly Holland | Published on March 12, 2014
Medically Reviewed by George Krucik, MD, MBA on March 12, 2014

Similar, But Different

Amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) are neurodegenerative diseases that impact the central nervous system. Both diseases attack the body’s nerves and muscles. In many ways, these two diseases are very similar. However, key differences determine a lot about treatment and outlook.

What Is ALS?

ALS, also known as Lou Gehrig’s disease, is a progressive and fatal disease. ALS greatly impacts the brain and central nervous system. In a healthy body, motor neurons in the brain send signals throughout the

body, telling muscles and body systems how to work. ALS slowly destroys those neurons, preventing them from working correctly. 

Eventually, ALS destroys the neurons completely. When this happens, the brain can no longer give commands to the body, and individuals with late-stage ALS become paralyzed. 

What Is MS?

MS is a central nervous system disorder that impacts the brain and spinal cord. It destroys the protective coating on nerves. This slows the relay of instructions from the brain to the body, making motor functions difficult.

MS is rarely completely debilitating or fatal. Some people with MS will experience mild symptoms for many years of their lives but never become incapacitated because of it. Others, however, may experience a rapid progression of symptoms and quickly be unable to care for themselves.


Both diseases attack and destroy the body, affecting muscle and nerve function. For that reason, they share many of the same symptoms, especially in early stages. Initial symptoms include:

  • muscle weakness and stiffness
  • loss of coordination and muscle control
  • difficulty moving limbs 

But the symptoms become quite different. People with MS often experience greater mental impairment than people with ALS. And people with ALS typically develop greater physical difficulties. 

Difference: Mental Capabilities

People with MS and ALS may face memory problems and cognitive impairment. However, people with MS can experience severe mental changes, including mood swings, depression, and an inability to focus or multitask.

For people with ALS, symptoms remain largely physical. In fact, mental function remains intact even when ALS has claimed most of a person’s physical capabilities. 

Difference: Autoimmune Disease

MS is an autoimmune disease. Autoimmune diseases occur when the immune system mistakenly attacks normal, healthy parts of the body as if they were foreign and dangerous. In other words, the body tries to destroy itself.

In the case of MS, the body mistakes myelin—a protective sheath that coats the outside of the nerves—for an invader and tries to destroy it. ALS is not an autoimmune disease, and its cause is unknown. 

Difference: Demyelination

MS targets and attacks myelin in a process called demyelination, hindering the nerves from performing as well as they once did. ALS, On the other hand, attacks the nerves first. In ALS, the demyelination process begins later, after the nerves have begun to die.

A magnetic resonance imaging (MRI) scan can detect demyelination. Doctors can use MRI results to distinguish between the two conditions.

Difference: Prognosis

ALS brings all people to the same end: incapacitation. According to the National Institute of Neurological Disorders and Stroke, eventually all individuals with ALS will become unable to walk, stand, or move about without help. They also may develop great difficulty swallowing and chewing. Ultimately, ALS is fatal. 

The outlook isn’t as clear with MS. Symptoms of MS may come and go, depending on the type of MS you have. You may experience an attack and then symptoms disappear for days, weeks, even years. The progression of MS differs from person to person. However, it’s rarely debilitating or fatal. 

Life with MS and ALS

Though both diseases appear to have much in common during the earliest stages, the progression, treatments, and prognoses for ALS and MS are very different. However, in both cases treatment paves the path toward a healthier, more fulfilling life as long as possible.

People with either condition should rely on their doctors to develop a plan that can help them get through the ups and downs of their disease as smoothly as possible.

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