Does Stephen Hawking really have ALS, or something else?

British physicist and mathematician, Stephen Hawking, was hospitalized in London on Monday with a respiratory infection. Beginning at age 21, Hawking has experienced progressive loss of muscle function leaving him nearly completely paralyzed and only able to communicate through a computerized voice (which he jokes “gives him an American accent”). Despite his disability, Professor Hawking has had a long and distinguised career studying “black holes” and other remarkable features of the universe. Unlike many scientists, he is also a gifted communicator of scientific concepts and is the author of several books, including some for children. Much like Albert Einstein, Hawking has become a cultural icon, playing himself in several episodes of The Simpsons and Futurama and having a toy action figure (no doubt representing the creative action of his fertile mind) designed after him.

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Although it is frequently reported that Hawking suffers from Amoytrophic Lateral Sclerosis (ALS), or Lou Gehrig Disease, most medical experts believe that what he actually suffers from is a related illness called Spinal Muscular Atrophy (SMA). Both ALS and SMA are diseases where nerve cells that control muscles (“motor neurons”) are damaged. Muscle cells depend on stimulation from nerves to function, and without this stimulation, muscle cells weaken or die. This leads to the classic symptoms of progressive muscle weakness. In both diseases, mental functioning remains normal.

There are major differences between the two diseases. Spinal Muscular Atrophy occurs when a “survivor motor neuron” gene is deleted or mutated, preventing the creation of a protein necessary for muscle strength. This disease varies in severity; the younger the age of onset, the more severe the symptoms. Infants with the disease most likely die before two years of age. Adult onset is associated with a much better prognosis, and the potential for a normal life expectancy. On the other hand, it is unknown what causes Amyotrophic Lateral Scherosis. It most frequently occurs in adults over 40. Progressive muscle weakness ultimately affects the respiratory muscles leading to respiratory failure and most patients die within 3 to 5 years from the onset of symptoms. Both diseases may eventually be treated or cured by stem cell therapy.

About Spinal Muscular Atrophy (SMA)

About Amyotrophic Lateral Sclerosis (ALS)


Mark Boguski, M.D., Ph.D. is on the faculty of Harvard Medical School and is a member of the Society for Participatory Medicine, "a movement in which networked patients shift from being mere passengers to responsible drivers of their health" and in which professional health care providers encourage "empowered patients" and value them as full partners in managing their health and wellness.


  1. Sam

    March 31, 2017 at 7:42 pm

    So this article never really answers the question of whether Stephen Hawking has ALS or SMA. I get that there may not be a conclusive answer but don’t just leave us hanging

    • Dr. Michele Berman

      April 3, 2017 at 9:53 am

      He must have SMA. If he had ALS, he’d been dead long ago.

      • Lucy Marie

        August 10, 2017 at 11:17 pm

        SMA is different from ALS. Stephen Hawking would be classified as SMA type 3 or 4 if he had SMA due to the age he got symptoms and it does not match symptoms at all. Totally different. The only way to know is an SMA blood test. I am sure he did one. I think he has a very rare ALS disease.

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