No one knows the cause, but it results in a creeping paralysis as neurons, or nerve cells, in the brain and spinal cord that control movement are progressively destroyed. On average, patients die within five years of the first symptoms, as paralysis leaves them unable to eat or breathe.
Caspases are enzymes that signal a damaged or worn out cell to commit suicide.
If doctors could block the caspases' action, they might be able to save important nerve cells. If humans had a similar result, that would equal another 14 months of life, said Dr. Leon Charash, medical adviser to the Muscular Dystrophy Association, which helped fund Friedlander's work. In contrast, the only ALS drug sold today prolongs survival by about three months. Equally important, Friedlander stressed, was his discovery that caspases don't just abruptly kill off a damaged cell. Instead, their activity in one cell is essentially contagious, affecting the secretion of toxic substances that make neighboring neurons too sick to work properly.