Amyotrophic lateral sclerosis (ALS), also referred to as motor neurone disease (MND), and sometimes referred to as Lou Gehrig's disease in the United States. ALS (Amyotrophic Lateral Sclerosis) is a degenerative disease that usually attacks both upper and lower motor neurons and causes break down throughout the brain and spinal cord. A common first symptom is a painless weakness in a hand, foot, arm or leg, which occurs in more than half of all cases. Other early symptoms include speech swallowing or walking difficulty. Lou Gehrig first brought national and international attention to the disease in 1939 when he abruptly retired from baseball after being diagnosed with ALS. Most commonly, the disease strikes people between the ages of 40 and 70, and as many as 30,000 Americans have the disease at any given time.