Although multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) share some similarities, there are key differences between the two disorders in terms of progression, treatment, and outlook.
MS is an immune-mediated disorder in which the patient’s own immune system mistakenly attacks the protective covering around nerve cells called the myelin sheath. As myelin is destroyed, nerve signals that travel along nerve cell extensions called axons are delayed or lost.
ALS, also known as Lou Gehrig’s disease, is a progressive disorder in which the nerve cells that control muscles become damaged and die. Without these cells, nerve signals cannot get from the brain to the muscles. With time, they begin to waste away, or atrophy.
Similarities between MS and ALS
Both MS and ALS are neurodegenerative diseases that affect the central nervous system, ultimately affecting a person’s mobility.
People with either disorder may experience muscle stiffness and spasms that interfere with movement. Muscle weakness and fatigue can also mark these diseases. Both diseases can affect the ability to walk, through uncooperative muscles as well as clumsiness.
Damage to the nervous system may also lead to slurred speech in both conditions.
Both diseases are characterized by sclerosis, which means scarring, with people developing several areas of lesions in response to nerve damage. In MS, the protective myelin coat surrounding nerve fibers is destroyed, a process known as demyelination. In ALS, motor neurons are damaged; a similar demyelination process occurs, but it begins later after neurons have already begun to die.
ALS and MS are also similar in that their exact causes are unknown, and neither currently has a cure.
Because both diseases have some similar symptoms, especially in the early stages, they initially may be confused with one another. Many of their symptoms also overlap with those of other neurodegenerative diseases. Because there is no single test to confirm either disease, reaching a diagnosis can take time as doctors rule out other disorders through a detailed study of a patient’s medical history, and the results of several diagnostic tests and examinations.
Unlike in ALS, where a person’s condition continuously and rapidly deteriorates, the course of MS can be unpredictable and differ from person to person. Doctors cannot predict the severity, rate of progression, or specific symptoms of MS at the time of diagnosis.
As the two diseases progress, they become more and more distinct. In its later stages, MS can have a significant impact on a patient’s mobility, vision, bowel and bladder control, emotional health, and cognitive function. In terms of physical abilities, MS rarely leaves people completely debilitated.
In contrast, in the late stages of ALS, patients are completely debilitated and paralyzed. They continue to lose physical control until they can no longer swallow or breathe on their own, ultimately becoming dependent on mechanical ventilation. Some patients may arrive at a state called locked-in syndrome, where their mind is fully intact, but they have lost all voluntary control over their body’s movements.
Most MS patients have a normal or near-normal life expectancy, while ALS considerably shortens a person’s life expectancy. The average survival time after diagnosis for people with ALS is about three to five years, although as many as 10% of patients may live 10 years or longer.
MS is two to three times more common in women than in men, while men are at a slightly higher risk of developing ALS than women. It is not clear why this might be.
MS is most commonly diagnosed in people ages 20 to 50, while ALS is typically diagnosed later in life at an average age of 60.
MS is more common than ALS. In the U.S., ALS is considered a rare disease, with fewer than 20,000 known cases and a prevalence of about 5 in every 100,000 people. An estimated 1 million people in the U.S., and about 2.5 million worldwide, are thought to be living with MS.
There is currently no cure for either disease. Treatments involve medications to slow the progression, increase patient comfort, and prevent complications.
Treatments for MS fall into two major categories: immunomodulatory medications to control the immune system and inflammation, and supportive therapies that help with symptoms. Lifestyle changes, such as diet and exercise, may also be of help.
Two major treatments are currently approved for ALS: Radicava (edavarone), and different formulations of riluzole, including Rilutek, Tiglutik, and Exservan. These medications are intended to help slow progression of the disease. There are also several symptomatic treatments and non-drug therapies, such as physiotherapy, available to help patients.
Last updated: March 12, 2021
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