This disease is a disorder involving loss of the use and control of muscles. The nerves controlling these muscles shrink and disappear, which results in loss of muscle tissue due to the lack of nervous stimulation. Muscle strength and coordination decreases, beginning with the voluntary muscles. There may be a loss of nervous stimulation to semi-voluntary muscles, such as the muscles that control breathing and swallowing. There is no effect on ability to think or reason.
ALS affects approximately 1 out of 100,000 people. It appears to be genetic and therefore runs in families. The disorder affects men more often than women. Symptoms usually do not develop until adulthood. There is no way to prevent Lou Gehrig's disease, as it is commonly called. Genetic counseling is advised if there is a family history of ALS.