Amyotrophic lateral sclerosis or ALS, is a progressive nervous system disease that affects nerve cells in the brain and spinal cord, causing loss of muscle control. Signs and symptoms might include: Difficulty walking or doing normal daily activities Tripping and falling Weakness in your legs, feet or ankles Hand weakness or clumsiness Slurred speech or trouble swallowing Muscle cramps and twitching in your arms, shoulders and tongue Inappropriate crying, laughing or yawning Cognitive and behavioral changes Established risk factors for ALS include: Heredity Age Sex Genetics Environmental factors, such as the following, might trigger ALS. Smoking. Smoking is the only likely environmental risk factor for ALS. The risk seems to be greatest for women, 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 single 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 unclear what about military service might trigger the development of ALS. It might include exposure to certain metals or chemicals, traumatic injuries, viral infections, and intense exertion. As the disease progresses,  ALS causes complications, such as: *Breathing Problems *Speaking Problems *Eating Problems *Dementia