Lou Gehrig's Disease, also known as amyotrophic lateral sclerosis (ALS), is a progressive neurodegenerative disease that affects neurons in the brain and spinal cord. It causes weakness and paralysis as the motor neurons die and the brain loses ability to initiate and control muscle movement. There is no cure for ALS, though some drugs can treat symptoms, and researchers are investigating potential genetic and viral causes as the disease sometimes runs in families. Famous individuals like baseball player Lou Gehrig and physicist Stephen Hawking had ALS.