Stephen Hawking was disabled by amyotrophic lateral sclerosis (ALS), a disease that progressively destroys the nerve cells controlling voluntary muscle movement. He was diagnosed at age 21, while studying at Cambridge in 1963, and doctors initially gave him roughly two years to live. He survived for 55 more years, dying in 2018 at age 76.
How ALS Affected His Body
ALS attacks two types of nerve cells: the upper motor neurons in the brain and the lower motor neurons in the spinal cord and brainstem. As these neurons die, scar tissue replaces them, and the muscles they once controlled weaken and shrink. The brain remains intact, meaning the person stays fully aware as their body gradually stops responding to commands. Hawking once described it as being trapped inside a body that was slowly shutting down while his mind worked as well as ever.
The disease typically starts with subtle clumsiness or weakness in a hand or foot, then spreads. In Hawking’s case, his doctors noted it was an atypical presentation. His ALS progressed far more slowly than expected and, by some accounts, eventually “burnt itself out,” stabilizing rather than continuing its usual relentless decline.
Why He Survived So Long
Most people with ALS die within two to five years of diagnosis, usually when the disease reaches the muscles that control breathing. Hawking’s survival for more than five decades puzzled neurologists. Two factors likely played a role.
First, his age at onset. ALS predominantly strikes people between 50 and 60. Only about 5% of patients develop symptoms before age 30, and the prognosis for younger patients is significantly better than for those diagnosed in middle age. Hawking was diagnosed at 21, placing him in the rarest and most favorable category.
Second, his disease followed an unusual trajectory. After an initial period of decline, the progression slowed dramatically. Doctors described his case as atypical from the beginning, and his relatively stable plateau over several decades remains one of the most extreme examples of slow-progressing ALS on record.
The Timeline of His Physical Decline
Hawking’s disability didn’t happen overnight. It unfolded over decades, each stage stripping away another layer of physical independence.
In the late 1960s, a few years after his diagnosis, his mobility deteriorated to the point where he needed crutches and could no longer stand to give lectures. By the end of that decade, he reluctantly agreed to use a wheelchair. He initially used standard motorized models and became known for driving them recklessly around Cambridge. By the early 1990s, he had lost enough hand function that he could no longer operate the chair’s controls himself.
The most dramatic turning point came in 1985. While visiting the CERN research facility in Geneva, Hawking caught pneumonia. The infection was life-threatening, and doctors performed an emergency tracheostomy, cutting an opening in his throat to help him breathe. The procedure saved his life but destroyed his ability to speak. From that point on, he required round-the-clock nursing care, funded by grants from several foundations.
How He Communicated After Losing Speech
After the tracheostomy, Hawking initially communicated by raising his eyebrows as a caregiver pointed to letters on a spelling card. This was painfully slow. He soon adopted a computer-based system that let him select words on a screen, which were then converted into his now-famous synthesized voice.
At first, he operated this system using a handheld clicker. As ALS continued to weaken his hands, he switched to a sensor mounted on his glasses that detected tiny movements in his right cheek muscle. An infrared beam measured changes in light caused by the cheek twitch, translating that single motion into text. Using this method, he could produce roughly one to two words per minute. It was extraordinarily slow, but it allowed him to write books, deliver lectures, and correspond with colleagues for more than three decades after losing his voice.
What Stayed Intact
ALS selectively destroys motor neurons. It does not damage the parts of the brain responsible for thinking, memory, or personality. Hawking’s intellect was completely unaffected. He published his bestselling book “A Brief History of Time” three years after the tracheostomy, produced groundbreaking theoretical work on black holes and cosmology well into his 70s, and maintained a sharp, famously dry sense of humor throughout his life. His career is one of the clearest demonstrations that ALS is a disease of the body, not the mind.