This document provides information about Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease. It defines ALS as a condition where the motor neurons that control muscle movement start to break down and die, preventing the brain from sending signals to the muscles so they cannot move. An estimated 30,000 Americans have ALS at any given time. While the cause is unknown, some scientists believe excessive levels of the neurotransmitter glutamate may damage and kill motor neurons through a chain reaction effect. The document outlines how neurotransmitters normally work and the theory that too much glutamate causes this chain reaction leading to motor neuron death and muscle paralysis. ALS can affect people of any age, race or background and