Amyotrophic lateral sclerosis (ALS) causes a slow degeneration of nerve cells that control muscle movements. As a result, people with ALS gradually lose the ability to control their muscles. Fortunately, their capacity to think and remember things usually is not affected. ALS is also known as Lou Gehrig's disease, after the famous U.S. baseball player who developed the disease.
The cause of ALS remains unknown. ALS generally strikes patients between the ages of 50 and 70. It affects men slightly more often than women. Some cases appear to be inherited. Certain genes may increase the risk of developing the illness.