Over 100 years after its discovery by Dr. Alois Alzheimer, the disease named after the German psychiatrist remains something of a mystery. Dr. Sam Gandy, reporting for ABC News, explores the nature and the mystery of Alzheimer's disease and describes what scientists know for sure about the disorder and what remains to be discovered. Dr. Gandy also details current treatment options like Aricept, Exelon, and Razadyne and talks about the future of Alzheimer's medications.