Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disorder that primarily affects the motor neurons in the brain and spinal cord. These nerve cells control the voluntary muscles, and their degeneration leads to increasing weakness, atrophy, and eventual paralysis. This disease is highly variable in its progression, meaning the time a person can live with ALS is not a single, fixed number.
The Typical ALS Lifespan and Immediate Prognosis
The average survival time for a person diagnosed with ALS is typically between two and five years from the onset of symptoms. The ultimate limitation on lifespan in ALS is primarily due to the progressive weakness of the respiratory muscles.
As the motor neurons controlling the diaphragm and chest muscles fail, the ability to breathe effectively is lost, leading to respiratory failure. This physiological outcome is the most common cause of death for people with ALS. Despite the common prognosis, the disease course is highly heterogeneous, and some individuals live significantly longer than the average.
A smaller percentage of people, about 10 to 20%, survive five years or more after the initial symptoms appear. Furthermore, about 5 to 10% of people with ALS live for a decade or longer, and a small group of around 5% may live for 20 years or more.
Key Factors That Influence Survival Time
One of the most significant factors is the site where the initial symptoms appear, referred to as the site of onset. ALS is broadly categorized into bulbar onset and limb onset, each carrying a different prognosis.
Bulbar-onset ALS involves the muscles controlling speech and swallowing, and it is generally associated with a shorter survival time. This form of the disease can progress more quickly to affect the respiratory muscles because of the proximity of the involved motor neurons. Conversely, limb-onset ALS, which begins in the arms or legs, is often linked to a slower progression and a longer median survival time.
Age at the time of symptom onset or diagnosis is another determining factor in the overall prognosis. Younger individuals who develop ALS often experience a more gradual disease course and tend to have longer survival times. For example, people diagnosed before the age of 40 may live for 10 years or more, whereas those diagnosed after age 80 often face a median survival of less than two years.
Beyond the site and age of onset, the initial rate of disease progression is considered one of the most reliable predictors of survival. The speed at which muscle function declines in the early stages of the disease is a strong indicator of the overall trajectory.
Medical Interventions for Extending Life
Specific medical interventions are available that can actively prolong life beyond the expected timeline. A primary strategy involves managing the inevitable decline in respiratory function through supportive devices. Non-invasive ventilation (NIV), using a mask to deliver pressurized air, is considered a standard of care for treating respiratory insufficiency.
NIV helps to lengthen survival and slow the decline in a patient’s forced vital capacity. For those whose respiratory muscles fail completely, invasive ventilation via a tracheostomy can extend life significantly, though this is a complex decision. These breathing supports directly address the main cause of death in ALS.
Nutritional support is another intervention that positively impacts survival, as maintaining body weight and caloric intake is crucial. As swallowing muscles weaken, difficulty eating and drinking can lead to malnutrition and dehydration. A percutaneous endoscopic gastrostomy (PEG) tube, or feeding tube, can be placed to bypass the mouth and throat, ensuring adequate nutrition.
There is evidence that using a PEG tube helps to stabilize weight and may prolong survival. In addition to supportive care, disease-modifying medications have been developed to slow the disease’s progression.
Riluzole, the first FDA-approved medication, has been shown to extend the time a person can live by slowing the rate of functional decline. Another medication, Edaravone (Radicava), is an antioxidant that has also been approved to slow the decline in physical function for people with ALS. These medications, when combined with aggressive supportive care, contribute to measurable extensions in lifespan.