Stephen Hawking Lived For Over 50 Years With ALS. Here’s Why That’s Unusual.

Hawking, who died this week at age 76, may have lived longer with ALS than any patient in history. Here's what we know about the disease, and his case in particular.

Amyotrophic lateral sclerosis, or ALS, is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord that control muscle movement.

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Rare and often fatal, it’s also called Lou Gehrig’s disease after the famed baseball player who was diagnosed with it in 1939, and ultimately died of the disease. In the UK, where Hawking was born, it’s called motor neurone disease (MND).

ALS attacks the nerves that carry impulses from the brain and spinal cord to the muscles throughout your body, causing them to degenerate and die. This affects the ability of these muscles to perform the voluntary movements needed for walking, talking, chewing, lifting objects, and more. When the muscles no longer receive the messages to move, they begin to weaken, twitch, and waste away (atrophy), according to the National Institute of Neurological Disorders and Stroke (NINDS).

"The disease robs the whole body of all active movements we make to do daily tasks," Lucie Bruijn, chief scientist at the ALS Association, told BuzzFeed News. In some cases there may also be cognitive impairment or dementia, Bruijn said, but many people with ALS (like Hawking) do not have changes in their ability to think.

Most people who get ALS are between the ages of 40 and 70, and it can affect anyone regardless of race, ethnicity, and socioeconomic status. Doctors do not know what causes ALS and there is currently no cure, although some treatments and technologies may help manage symptoms.

ALS eventually leads to paralysis and death. Every case is individual, but patients typically survive for three to five years after being diagnosed.

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The prognosis for ALS is not a good one, but there are some cases where people defy the odds, such as Hawking. About 10% of people will survive for 10 or more years. But the disease can also kill within months.

"The changes in ability to move progress faster for some than others, it's very variable," Bruijn said. Progression isn't always linear, either. "There are various stages of the disease, and some people progress quickly then maintain at that stage and later progress again," Bruijn said. However, it is very rare for there to be any improvement or to recover lost functions.

A person with ALS might die for a variety of reasons, but it's often from breathing problems due to the disease. "People usually succumb to not being able to breathe because the lungs depend on the diaphragm (a muscle) and its ability to contract and relax," Bruijn said.

The breathing problems caused by ALS can lead to exhaustion, infections like pneumonia, and respiratory failure. "Artificial breathing support and other technologies can really extend someone's ability to live longer," Bruijn said.

Stephen Hawking survived for over 50 years with ALS. The reason why he lived so long is not known, but doctors point to a combination of genetic and environmental factors.

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In Hawking's case, he was diagnosed in 1963 at age 21 and defied the odds to live for another 55 years until the age of 76. Hawking lived his entire adult life with the disease, and unlike those patients who experience cognitive impairment or dementia, Hawking continued to work as an astrophysicist and make major contributions to the study of black holes and space.

"He progressed to the point where he was unable to move or speak, but he used things like eye movement and other technologies to speak so he was mentally extremely active — he had a remarkably long, and in some ways healthy battle," Bruijn said. It is estimated that only 5% of people with ALS will live 20 years or longer. Hawking may have lived longer than any patient in history after an ALS diagnosis.

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So why did Hawking's case progress more slowly than others? There isn't a clear answer. "We do not know exactly why he lived for so long and every individual's journey is different, but genes and environment play a role in the progression of the disease," Bruijn said. In addition to the possible genetic and environmental factors that could've allowed Hawking to live longer, he had remarkable access to care and advanced technology.

"If you get assistance to move and speak, the quality of life will improve — the fact that he could continue to work is a huge aspect of mental health," Bruijn said. That being said, many patients with ALS will continue to decline regardless of any treatment or technology. "It's a very complex disease and his slow progression and long life just reflects the fact that it's very variable," Bruijn said. However, Hawking was likely an exception to the rule. It is unclear which type of ALS Hawking had, and whether this was a factor.

Hawking was a major force in the ALS and science communities, and his legacy inspired people all over the world.

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"Many people with ALS have looked to Hawking and gotten strength from his journey — it's important to respect and honor what he represented to the ALS community," Bruijn said. Hawking was also a major contributor to ALS research and supported initiatives to better understand the disease.

“Stephen Hawking has inspired me to focus on what I can do, rather than what my body can no longer do,” Stephen Winthrop, the ALS Association board of trustees chair, wrote of Hawking in a press release.

Attention for this rare disease skyrocketed with the Ice Bucket Challenge in the summer of 2014, which raised $115 million for ALS research projects. Researchers are continuing to study ALS and working toward a cure. "We are involved in studies globally to learn more about ALS and find new clues about genes and environmental factors and how they interact," Bruijn said.