Multiple sclerosis (MS) shares a number of similarities with amyotrophic lateral sclerosis (ALS), but key differences in the two diseases determine a lot about treatment and outlook.


Both MS and ALS are neurodegenerative diseases that attack the central nervous system and affect the nerves and muscles, impacting a person’s ability to move.

Both MS and ALS lead to memory problems and cognitive impairment, and neither disease has a cure.

Both conditions cause scarring or hardening around nerve cells called sclerosis, but the difference lies in the way sclerosis occurs.

In early stages, several symptoms of ALS and MS can be similar, like muscle stiffness, muscle spasms, difficulty walking, and fatigue. But as each disease progresses, differences between the two become apparent.



MS is an autoimmune disease that causes the body to attack the myelin sheath that insulates nerve cell fibers in the brain and the spinal cord. In contrast, ALS is a motor neuron disease that mainly affects the actual motor neuron cells in the brain and spinal cord.


Sclerosis in MS is caused by a breakdown in myelin. When demyelination occurs, signals from the brain to other parts of the body are interrupted.

In ALS, sclerosis damages the motor neurons, causing the myelin sheath to become harder. This leads to the loss of control of motor functions and muscle wasting.

Disease course

Unlike ALS, the course of MS is unpredictable and differs from person to person. The severity, rate of progression, and specific symptoms of MS cannot be predicted at the time of diagnosis.

Late stages

In later stages of MS, mobility is mainly affected but rarely leaves people completely debilitated. In the late stages of ALS, patients are completely debilitated and paralyzed.

Affected functions

Unlike ALS, which affects only the nerves involved in movement, MS can also affect nerves that control the senses (taste, smell, touch, and sight) and the bladder. MS can also have an impact on mental and emotional health, and cause sensitivity to temperature.

MS patients tend to experience greater mental impairment, while ALS patients typically exhibit physical difficulties.


MS is not a fatal disease. The majority of patients are expected to have a normal or near-normal lifespan. In contrast, ALS is a fatal disease with an average life expectancy of about three to five years post-diagnosis.


MS is more common in women and ALS is more common in men. The exact reason for this is not known.


MS is usually found earlier in life than ALS. MS is most commonly diagnosed in people ages 20 to 50, while ALS is most commonly diagnosed in people ages 40 to 70.


MS is not thought to be a genetically inherited disease, although people usually have a higher risk of developing the disease if a close relative (mother, father, or sibling) has MS. In contrast, around 10 percent of ALS cases are caused by mutated genes passed down directly from the parents.


MS is more common than ALS. In the U.S., an estimated 20,000 people have ALS, while more than 400,000 people are living with MS.

Note: Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.