What is ALS, the Disease Stephen Hawking Defied
When renowned physicist, cosmologist, and author Stephen Hawkins was diagnosed with ALS (amyotrophic lateral sclerosis), also known as Lou Gehrig’s disease, at age 21, the future for the then-Cambridge University student didn’t look promising and his years were numbered. But while reaching age 40 would have been a feat, Hawking has defied ALS and will celebrate his 70th birthday on Sunday, January 8.
What is ALS?
ALS is a progressive neurodegenerative disease that attacks the nerve cells in the spinal cord and brain. The progression of the disease can be explained in this way:
- “Amyotrophic” can be broken down into its Greek derivatives: “A” means no, “myo” refers to muscle, and “trophic” means nourishment. Therefore, ALS is a disease characterized by no muscle nourishment.
- “Lateral” refers to the regions of a patient’s spinal cord where the nerve cells that have an impact on the muscles are located
- “Sclerosis,” or hardening is what happens to the areas of the body as the affected muscles degenerate
ALS typically first strikes people between the ages of 40 and 70, although it can appear earlier, as in the case of Stephen Hawking. Approximately 5,600 people in the United States receive a diagnosis of ALS each year, and life expectancy averages 2 to 5 years from the time of diagnosis. Up to 10% of patients live more than 10 years.
In the early stages of the disease, symptoms may include increasing weakness in the muscles of the arms and legs, and difficulty swallowing, speaking, or breathing. As different regions of the body no longer receive signals from motor neurons, muscles in those areas begin to atrophy.
The areas of the body not affected by the death of neurons are the heart and the digestive system, which are not composed of the same kind of muscle as are voluntary muscles. Therefore, a person with ALS can continue to have a strong heart and digest their food.
If the disease progresses to the point where it affects breathing, patients typically require a ventilator to survive. Hawking has not needed such breathing assistance despite living with the disease for nearly half a century.
ALS: Causes and Prognosis
Experts do not know what causes ALS, but they have some theories. One involves mutations of a specific gene that produces the SOD1 enzyme, which is a potent antioxidant that protects the body against cell-damaging free radicals.
Another theory concerns a chemical messenger called glutamate, which appears in higher levels in people with ALS than in healthy individuals. Studies indicate that neurons begin to die when they are exposed to glutamate for long periods of time.