Amyotrophic lateral sclerosis (a-my-o-TROE-fik LAT-ur-ul skluh-ROE-sis), known as ALS, is a nervous system disease that affects nerve cells in the brain and spinal cord. ALS causes loss of muscle control. The disease gets worse over time.
ALS is often called Lou Gehrig’s disease after the baseball player who was diagnosed with it. The exact cause of the disease is still not known. A small number of cases are inherited.
ALS often begins with muscle twitching and weakness in an arm or leg, trouble swallowing or slurred speech. Eventually ALS affects control of the muscles needed to move, speak, eat and breathe. There is no cure for this fatal disease.
Established risk factors for ALS include:
- Genetics. For about 10% of people with ALS, a risk gene was passed down from a family member. This is called hereditary ALS. In most people with hereditary ALS, their children have a 50% chance of inheriting the gene.
- Age. Risk increases with age up to age 75. ALS is most common between the ages of 60 and the mid-80s.
- Sex. Before the age of 65, slightly more men than women develop ALS. This sex difference disappears after age 70.
Environmental factors, such as the following, have been associated with an increased risk of ALS.
- Smoking. Evidence supports that smoking is an environmental risk factor for ALS. Women who smoke seem to be at even higher risk, particularly after menopause.
- Environmental toxin exposure. Some evidence suggests that exposure to lead or other substances in the workplace or at home might be linked to ALS. Much study has been done, but no one agent or chemical has been consistently associated with ALS.
- Military service. Studies indicate that people who have served in the military are at higher risk of ALS. It’s not clear what about military service might trigger ALS. It might include exposure to certain metals or chemicals, traumatic injuries, viral infections, or intense exertion.