"Age is the single greatest risk factor for developing Alzheimer's disease," reports Dr. Gary Small, author of "The Alzheimer's Prevention Program." It is a devastating illness affecting not only the patient, but their families and caregivers. Alzheimer's afflicts about 5 million people in the U.S. now. But because we are living longer, an estimated 16 million people will likely have the disease by 2050. In this video, Dr. Small relates what scientists are learning about this heart breaking illness.