ALS, or amyotrophic lateral sclerosis, is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. A-myo-trophic comes from the Greek language. "A" means no. "Myo" refers to muscle, and "Trophic" means nourishment – "No muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that signal and control the muscles are located. As this area degenerates, it leads to scarring or hardening ("sclerosis") in the region.
Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their demise. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, people may lose the ability to speak, eat, move and breathe.
There are two different types of ALS, sporadic and familial. Sporadic, which is the most common form of the disease in the U.S., accounts for 90 to 95 percent of all cases. It may affect anyone, anywhere. Familial ALS (FALS) accounts for 5 to 10 percent of all cases in the U.S. Familial ALS means the disease is inherited. In those families, there is a 50% chance each offspring will inherit the gene mutation and may develop the disease.
Every 90 minutes, someone is diagnosed with the disease and someone passes away from it.
Most people who develop ALS are between the ages of 40 and 70, with an average age of 55 at the time of diagnosis. However, cases of the disease do occur in people in their twenties and thirties. ALS is 20 percent more common in men than in women. However, with increasing age, the incidence of ALS is more equal between men and women. For unknown reasons, military veterans are up to twice as likely to be diagnosed with the disease as the general public.