Alzheimer’s disease affects millions of people worldwide; it’s often a disease that is undetectable until it’s too late. However, a new set of national guidelines are being released that will help catch signs of the disease earlier. David Shenk, author of “The Forgetting: Alzheimer’s, Portrait of an Epidemic,” explains the latest guidelines. The guidelines concern methods that assess brain changes including brain scans, tests of cerebral spinal fluid and other biomarkers. The ability to find markers means more research into the possibility of developing drugs to combat Alzheimer’s.