Editor's note: Stephen Hawking passed away on Wednesday after a long battle with amyotrophic lateral sclerosis (ALS). This piece has been updated to reflect that.
In January, famed theoretical physicist Stephen Hawking celebrated his 76th birthday. And despite the fact that Hawking's research changed the way people think about the creation of the universe, turning 76 may have actually been one of his most impressive accomplishments: Hawking was never supposed to have survived past the age of 25.
While pursuing a research position at Cambridge in 1962, Hawking was diagnosed with a motor neuron disease, later revealed to be amyotrophic lateral sclerosis, or ALS. When a patient is affected by ALS, the motor neurons in his brain and spinal column start to progressively weaken and die, which in turn affects muscles that control voluntary movements. At first, these muscles will weaken or stiffen, which can result in slurred speech or an inability to button or zip clothes. But eventually, these muscles will cease to function altogether, and within months or years, patients lose the ability to walk, speak, and breathe independently.
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According to information from the ALS Association, the majority of patients with ALS die between two and five years after being diagnosed. Only ten percent of patients go on to live ten years past their diagnosis.
So far, Hawking has managed to survive an astounding 57 years.
So how has Hawking managed to live so long? “The honest answer is, we don't have a clue,” Jeffrey Rothstein, professor of neurology and neuroscience at Johns Hopkins and Director of the Robert Packard Center for ALS Research, told The Daily Beast. “I've had patients die three months after a diagnosis, and I've had others live 27 years. The disease runs its own course. It’s very individual.”
One clue to understanding survival rates is in our DNA. According to Rothstein, anywhere from five to 10 percent of ALS cases are “familial,” meaning that a defective gene or genes get passed down through families. Other cases are considered “sporadic”—either a gene mutation that occurred in a patient with no family history, or an unknown cause. Genes may determine who gets ALS—and who survives the longest.
“One gene mutation called A4V causes a very short and aggressive disease pattern,” Rothstein said. “In the U.S., those patients tend to live about nine months.”
However, an Australian patient with the same genetic mutation tends to live several years longer. “We don't understand why that is yet,” Rothstein said. “But we think that other genes in the patients' bodies mitigate the toxicity of that mutation – in other words, they stop it and slow it down. It tells us, whether the disease is fast or slow, that depends on the genes in your body.” Currently, researchers have identified around 20 different gene mutations that cause ALS.
Another factor that played into Hawking's longevity was his use of a ventilator.
“People die from ALS because they can't breathe,” Rothstein said. When the motor neurons that control the patient's lungs weaken, patients gradually lose breathing capacity. As well as being unable to take in air, they can't exhale carbon dioxide either. “When the carbon dioxide builds up, it makes your blood acidic. That affects your heart, and you have a heart attack.”
Patients who choose to employ a ventilator, however, live longer. “If you intervene and use a ventilator, you'll die eventually of something age- or infection-related, but you won't die because you're unable to breathe,” Rothstein said. Most families opt out of using a ventilator, citing quality-of-life issues, Rothstein said. “We support it, but most patients just choose not to have that. The demands on the family can be tremendous.”
But whether it's genetics, modern technology, or some other reason, what might be the most remarkable about Hawking's disease is not how long he'd survived, but how brilliant his mind continued to be despite the disease, Robert Kalb, Director of the Les Turner ALS Research and Patient Center at Northwestern Medicine, said.
“ALS has been described as purely a motor disease, and the only thing affected is the motor cortex,” he explained. “But what we're learning now is that as people get further into the disease, they often develop cognitive problems with thinking and memory.” This occurs even though the motor cortex is in a different area in the brain than the part responsible for logic and memory. “Very often, your logic can be impaired,” Kalb said.
A month before Hawking's death, Kalb was still in awe. “Hawking has lived with this disease so long, and yet he still comes up with these brilliant ideas. The fact that he has no problems with memory and thinking and cognitive function is remarkable.”
Updated to correct Hawking’s age. We regret the error.
