Amyotrophic lateral sclerosis (ALS)(筋委縮性側索硬化症), or Lou Gehrig's disease, is a degenerative(退行性の)disease that affects motor neurons(運動ニューロン)in the brain and spinal cord, causing weakness, paralysis, and eventual death. There is currently only one drug available for people with the incurable disease, and a two-year study of another drug, which had previously shown some benefit to ALS sufferers, has found that the treatment does not slow the progression of muscle weakness. Two previous studies had looked at whether the growth hormone known as insulin-like growth factor-1 (IGF-1) could treat ALS, but they had produced conflicting results.